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authorache <ache@FreeBSD.org>1995-01-12 02:48:42 +0000
committerache <ache@FreeBSD.org>1995-01-12 02:48:42 +0000
commit307f1b2ed7de18997d86783314314155e9adc8e7 (patch)
tree98f0951a522092632797ac19bdc0f35e7bfee010 /gnu/usr.bin/as
parent9e1dbd7ec1b0e82249f6d0ed10698d070f15aa2e (diff)
downloadFreeBSD-src-307f1b2ed7de18997d86783314314155e9adc8e7.zip
FreeBSD-src-307f1b2ed7de18997d86783314314155e9adc8e7.tar.gz
Infopage installation
Diffstat (limited to 'gnu/usr.bin/as')
-rw-r--r--gnu/usr.bin/as/doc/Makefile188
-rw-r--r--gnu/usr.bin/as/doc/as-all.texinfo4995
2 files changed, 4997 insertions, 186 deletions
diff --git a/gnu/usr.bin/as/doc/Makefile b/gnu/usr.bin/as/doc/Makefile
index f2c319f..77a0cf2 100644
--- a/gnu/usr.bin/as/doc/Makefile
+++ b/gnu/usr.bin/as/doc/Makefile
@@ -1,187 +1,3 @@
-# This file was generated automatically by configure. Do not edit.
-host_alias = i386
-host_cpu = i386
-host_vendor = unknown
-host_os = scosysv322
-target_alias = i386
-target_cpu = i386
-target_vendor = unknown
-target_os = scosysv322
-target_makefile_frag =
-host_makefile_frag =
-site_makefile_frag =
-links =
-VPATH = .
-ALL=all.internal
-# Makefile for GNU Assembler documentation
-# - see pretex.m4 for discussion of preprocessor definitions
-# Copyright (C) 1987-1992 Free Software Foundation, Inc.
-
-#This file is part of GNU GAS.
-
-#GNU GAS is free software; you can redistribute it and/or modify
-#it under the terms of the GNU General Public License as published by
-#the Free Software Foundation; either version 2, or (at your option)
-#any later version.
-
-#GNU GAS is distributed in the hope that it will be useful,
-#but WITHOUT ANY WARRANTY; without even the implied warranty of
-#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-#GNU General Public License for more details.
-
-#You should have received a copy of the GNU General Public License
-#along with GNU GAS; see the file COPYING. If not, write to
-#the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
-
-# The targets for external use include:
-# all, doc, proto, install, uninstall, includes, TAGS,
-# clean, cleanconfig, realclean, stage1, stage2, stage3, stage4.
-
-# Variables that exist for you to override.
-# See below for how to change them for certain systems.
-
-srcdir = .
-
-prefix = /usr/local
-
-bindir = $(prefix)/bin
-datadir = $(prefix)/lib
-libdir = $(prefix)/lib
-mandir = $(datadir)/man
-man1dir = $(mandir)/man1
-man2dir = $(mandir)/man2
-man3dir = $(mandir)/man3
-man4dir = $(mandir)/man4
-man5dir = $(mandir)/man5
-man6dir = $(mandir)/man6
-man7dir = $(mandir)/man7
-man8dir = $(mandir)/man8
-man9dir = $(mandir)/man9
-infodir = $(datadir)/info
-includedir = $(prefix)/include
-docdir = $(datadir)/doc
-
-SHELL = /bin/sh
-
-INSTALL = install -c
-INSTALL_PROGRAM = $(INSTALL)
-INSTALL_DATA = $(INSTALL)
-
-AR = ar
-AR_FLAGS = qv
-BISON = bison
-MAKEINFO = makeinfo
-RANLIB = ranlib
-
-# What version of the manual you want (see *.m4); "all" includes everything
-CONFIG=all
-
-# Sun/Berkeley m4 doesn't have all the things we need; use GNU or sV
-M4=gm4
-#M4=/usr/5bin/m4
-
-# Directory for gas source
-srcdir = .
-
-# Where to find texinfo.tex to format docn with TeX
-TEXIDIR = $(srcdir)/../texinfo/fsf
-
-#### host, target, and site specific Makefile frags come in here.
-##
-
-all:
-clean:
-install:
- $(INSTALL_DATA) $(srcdir)/as.1 $(man1dir)/as.1
-
-info: as.info
-
-as.info: as-${CONFIG}.texinfo
- makeinfo -o as.info as-${CONFIG}.texinfo
-
-install-info: as.info
- [ -d $(infodir) ] || mkdir $(infodir)
- for i in as.info* ; do \
- $(INSTALL_DATA) $$i $(infodir)/$$i ; \
- done
-
-as.dvi: as-${CONFIG}.texinfo
- TEXINPUTS=${TEXIDIR}:.:$$TEXINPUTS tex as-${CONFIG}.texinfo
- texindex as-${CONFIG}.??
- TEXINPUTS=${TEXIDIR}:.:$$TEXINPUTS tex as-${CONFIG}.texinfo
- mv as-${CONFIG}.dvi as.dvi
- rm as-${CONFIG}.?? as-${CONFIG}.???
-
-# ROFF doc targets as.ms, as.mm, as.me
-# (we don't use a variable because we don't trust all makes to handle
-# a var in the target name right).
-# roff output (-ms)
-as.ms: as-${CONFIG}.texinfo
- sed -e '/\\input texinfo/d' \
- -e '/@c TEXI2ROFF-KILL/,/@c END TEXI2ROFF-KILL/d' \
- -e 's/{.*,,/{/' \
- as-${CONFIG}.texinfo | \
- texi2roff -ms >as.ms
-
-# roff output (-mm)
-as.mm: as-${CONFIG}.texinfo
- sed -e '/\\input texinfo/d' \
- -e '/@c TEXI2ROFF-KILL/,/@c END TEXI2ROFF-KILL/d' \
- -e 's/{.*,,/{/' \
- -e '/@noindent/d' \
- as-${CONFIG}.texinfo | \
- texi2roff -mm | \
- sed -e 's/---/\\(em/g' \
- >as.mm
-
-# roff output (-me)
-as.me: as-${CONFIG}.texinfo
- sed -e '/\\input texinfo/d' \
- -e '/@c TEXI2ROFF-KILL/,/@c END TEXI2ROFF-KILL/d' \
- -e 's/{.*,,/{/' \
- as-${CONFIG}.texinfo | \
- texi2roff -me >as.me
-
-
-
-as-all.texinfo: as.texinfo pretex.m4 none.m4 all.m4
- ${M4} $(srcdir)/pretex.m4 $(srcdir)/none.m4 $(srcdir)/all.m4 $(srcdir)/as.texinfo >as-all.texinfo
-
-as-a29k.texinfo: as.texinfo pretex.m4 none.m4 a29k.m4
- ${M4} pretex.m4 none.m4 a29k.m4 as.texinfo >as-a29k.texinfo
-
-as-a29k-coff.texinfo: as.texinfo pretex.m4 none.m4 a29k-coff.m4
- ${M4} pretex.m4 none.m4 a29k-coff.m4 as.texinfo >as-a29k-coff.texinfo
-
-as-gen.texinfo: as.texinfo pretex.m4 none.m4 gen.m4
- ${M4} pretex.m4 none.m4 gen.m4 as.texinfo >as-gen.texinfo
-
-as-h8.texinfo: as.texinfo pretex.m4 none.m4 h8.m4
- ${M4} pretex.m4 none.m4 h8.m4 as.texinfo >as-h8.texinfo
-
-as-i80386.texinfo: as.texinfo pretex.m4 none.m4 i80386.m4
- ${M4} pretex.m4 none.m4 i80386.m4 as.texinfo >as-i80386.texinfo
-
-as-i960.texinfo: as.texinfo pretex.m4 none.m4 i960.m4
- ${M4} pretex.m4 none.m4 i960.m4 as.texinfo >as-i960.texinfo
-
-as-m680x0.texinfo: as.texinfo pretex.m4 none.m4 m680x0.m4
- ${M4} pretex.m4 none.m4 m680x0.m4 as.texinfo >as-m680x0.texinfo
-
-as-sparc.texinfo: as.texinfo pretex.m4 none.m4 sparc.m4
- ${M4} pretex.m4 none.m4 sparc.m4 as.texinfo >as-sparc.texinfo
-
-as-vax.texinfo: as.texinfo pretex.m4 none.m4 vax.m4
- ${M4} pretex.m4 none.m4 vax.m4 as.texinfo >as-vax.texinfo
-
-as-vintage.texinfo: as.texinfo pretex.m4 none.m4 vintage.m4
- ${M4} pretex.m4 none.m4 vintage.m4 as.texinfo >as-vintage.texinfo
-
-clean-info:
- rm -f as-${CONFIG}.* as.dvi as.info*
-
-force:
-
-Makefile: $(srcdir)/Makefile.in $(host_makefile_frag) $(target_makefile_frag)
- $(SHELL) ./config.status
+INFO = as-all
+.include <bsd.info.mk>
diff --git a/gnu/usr.bin/as/doc/as-all.texinfo b/gnu/usr.bin/as/doc/as-all.texinfo
new file mode 100644
index 0000000..99076ae
--- /dev/null
+++ b/gnu/usr.bin/as/doc/as-all.texinfo
@@ -0,0 +1,4995 @@
+
+
+\input texinfo @c -*-Texinfo-*-
+@c Copyright (c) 1991 1992 Free Software Foundation, Inc.
+@c %**start of header
+@setfilename as.info
+@settitle Using as
+@setchapternewpage odd
+@c @smallbook
+@c @cropmarks
+@c %**end of header
+
+@finalout
+@syncodeindex ky cp
+
+@c
+@ifinfo
+This file documents the GNU Assembler "as".
+
+Copyright (C) 1991 Free Software Foundation, Inc.
+
+Permission is granted to make and distribute verbatim copies of
+this manual provided the copyright notice and this permission notice
+are preserved on all copies.
+
+@ignore
+Permission is granted to process this file through Tex and print the
+results, provided the printed document carries copying permission
+notice identical to this one except for the removal of this paragraph
+(this paragraph not being relevant to the printed manual).
+
+@end ignore
+Permission is granted to copy and distribute modified versions of this
+manual under the conditions for verbatim copying, provided also that the
+section entitled ``GNU General Public License'' is included exactly as
+in the original, and provided that the entire resulting derived work is
+distributed under the terms of a permission notice identical to this
+one.
+
+Permission is granted to copy and distribute translations of this manual
+into another language, under the above conditions for modified versions,
+except that the section entitled ``GNU General Public License'' may be
+included in a translation approved by the Free Software Foundation
+instead of in the original English.
+@end ifinfo
+
+@titlepage
+@title Using as
+@subtitle The GNU Assembler
+@sp 1
+@subtitle January 1992
+@sp 1
+@sp 13
+The Free Software Foundation Inc. thanks The Nice Computer
+Company of Australia for loaning Dean Elsner to write the
+first (Vax) version of @code{as} for Project GNU.
+The proprietors, management and staff of TNCCA thank FSF for
+distracting the boss while they got some work
+done.
+@sp 3
+@author Dean Elsner, Jay Fenlason & friends
+@c edited by: pesch@cygnus.com
+@page
+@tex
+\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
+\xdef\manvers{\$Revision: 1.1 $} % For use in headers, footers too
+{\parskip=0pt
+\hfill \manvers\par
+\hfill \TeX{}info \texinfoversion\par
+}
+%"boxit" macro for figures:
+%Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
+\gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
+ \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
+#2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
+\gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
+@end tex
+
+Edited by Roland Pesch for Cygnus Support.
+
+@vskip 0pt plus 1filll
+Copyright @copyright{} 1991 Free Software Foundation, Inc.
+
+Permission is granted to make and distribute verbatim copies of
+this manual provided the copyright notice and this permission notice
+are preserved on all copies.
+
+Permission is granted to copy and distribute modified versions of this
+manual under the conditions for verbatim copying, provided also that the
+section entitled ``GNU General Public License'' is included exactly as
+in the original, and provided that the entire resulting derived work is
+distributed under the terms of a permission notice identical to this
+one.
+
+Permission is granted to copy and distribute translations of this manual
+into another language, under the above conditions for modified versions,
+except that the section entitled ``GNU General Public License'' may be
+included in a translation approved by the Free Software Foundation
+instead of in the original English.
+@end titlepage
+@page
+@node Top, Overview, (dir), (dir)
+@ifinfo
+This file is a user guide to the GNU assembler @code{as}.
+@end ifinfo
+@menu
+* Overview:: Overview
+* Invoking:: Command-Line Options
+* Syntax:: Syntax
+* Sections:: Sections and Relocation
+* Symbols:: Symbols
+* Expressions:: Expressions
+* Pseudo Ops:: Assembler Directives
+* Machine Dependent:: Machine Dependent Features
+* Copying:: GNU GENERAL PUBLIC LICENSE
+* Index:: Index
+@end menu
+
+@node Overview, Invoking, Top, Top
+@chapter Overview
+@iftex
+This manual is a user guide to the GNU assembler @code{as}.
+@end iftex
+
+@cindex invocation summary
+@cindex option summary
+@cindex summary of options
+Here is a brief summary of how to invoke @code{as}. For details,
+@pxref{Invoking,,Comand-Line Options}.
+
+@c We don't use deffn and friends for the following because they seem
+@c to be limited to one line for the header.
+@smallexample
+ as [ -a | -al | -as ] [ -D ] [ -f ]
+ [ -I @var{path} ] [ -k ] [ -L ]
+ [ -o @var{objfile} ] [ -R ] [ -v ] [ -w ]
+@c am29k has no machine-dependent assembler options
+@c h8/300 has no machine-dependent assembler options
+@c see md_parse_option in i960.c
+ [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ]
+ [ -b ] [ -norelax ]
+ [ -l ] [ -mc68000 | -mc68010 | -mc68020 ]
+ [ -- | @var{files} @dots{} ]
+@end smallexample
+
+@table @code
+@item -a | -al | -as
+Turn on assembly listings; @samp{-al}, listing only, @samp{-as}, symbols
+only, @samp{-a}, everything.
+
+@item -D
+This option is accepted only for script compatibility with calls to
+other assemblers; it has no effect on @code{as}.
+
+@item -f
+``fast''---skip preprocessing (assume source is compiler output)
+
+@item -I @var{path}
+Add @var{path} to the search list for @code{.include} directives
+
+@item -k
+Issue warnings when difference tables altered for long displacements.
+
+@item -L
+Keep (in symbol table) local symbols, starting with @samp{L}
+
+@item -o @var{objfile}
+Name the object-file output from @code{as}
+
+@item -R
+Fold data section into text section
+
+@item -v
+Announce @code{as} version
+
+@item -W
+Suppress warning messages
+
+@item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
+(When configured for Intel 960).
+Specify which variant of the 960 architecture is the target.
+
+@item -b
+(When configured for Intel 960).
+Add code to collect statistics about branches taken.
+
+@item -norelax
+(When configured for Intel 960).
+Do not alter compare-and-branch instructions for long displacements;
+error if necessary.
+
+@item -l
+(When configured for Motorola 68000).
+Shorten references to undefined symbols, to one word instead of two
+
+@item -mc68000 | -mc68010 | -mc68020
+(When configured for Motorola 68000).
+Specify what processor in the 68000 family is the target (default 68020)
+
+@item -- | @var{files} @dots{}
+Standard input, or source files to assemble
+@end table
+
+@menu
+* Manual:: Structure of this Manual
+* GNU Assembler:: as, the GNU Assembler
+* Object Formats:: Object File Formats
+* Command Line:: Command Line
+* Input Files:: Input Files
+* Object:: Output (Object) File
+* Errors:: Error and Warning Messages
+@end menu
+
+@node Manual, GNU Assembler, Overview, Overview
+@section Structure of this Manual
+
+@cindex manual, structure and purpose
+This manual is intended to describe what you need to know to use
+@sc{gnu} @code{as}. We cover the syntax expected in source files, including
+notation for symbols, constants, and expressions; the directives that
+@code{as} understands; and of course how to invoke @code{as}.
+
+This manual also describes some of the machine-dependent features of
+various flavors of the assembler.
+@refill
+
+@cindex machine instructions (not covered)
+On the other hand, this manual is @emph{not} intended as an introduction
+to programming in assembly language---let alone programming in general!
+In a similar vein, we make no attempt to introduce the machine
+architecture; we do @emph{not} describe the instruction set, standard
+mnemonics, registers or addressing modes that are standard to a
+particular architecture.
+You may want to consult the manufacturer's
+machine architecture manual for this information.
+
+
+@c I think this is premature---pesch@cygnus.com, 17jan1991
+@ignore
+Throughout this manual, we assume that you are running @dfn{GNU},
+the portable operating system from the @dfn{Free Software
+Foundation, Inc.}. This restricts our attention to certain kinds of
+computer (in particular, the kinds of computers that GNU can run on);
+once this assumption is granted examples and definitions need less
+qualification.
+
+@code{as} is part of a team of programs that turn a high-level
+human-readable series of instructions into a low-level
+computer-readable series of instructions. Different versions of
+@code{as} are used for different kinds of computer.
+@end ignore
+
+@c There used to be a section "Terminology" here, which defined
+@c "contents", "byte", "word", and "long". Defining "word" to any
+@c particular size is confusing when the .word directive may generate 16
+@c bits on one machine and 32 bits on another; in general, for the user
+@c version of this manual, none of these terms seem essential to define.
+@c They were used very little even in the former draft of the manual;
+@c this draft makes an effort to avoid them (except in names of
+@c directives).
+
+@node GNU Assembler, Object Formats, Manual, Overview
+@section as, the GNU Assembler
+
+GNU @code{as} is really a family of assemblers.
+If you use (or have used) the GNU assembler on one architecture, you
+should find a fairly similar environment when you use it on another
+architecture. Each version has much in common with the others,
+including object file formats, most assembler directives (often called
+@dfn{pseudo-ops)} and assembler syntax.@refill
+
+@cindex purpose of @sc{gnu} @code{as}
+@code{as} is primarily intended to assemble the output of the GNU C
+compiler @code{gcc} for use by the linker @code{ld}. Nevertheless,
+we've tried to make @code{as} assemble correctly everything that the native
+assembler would.
+Any exceptions are documented explicitly (@pxref{Machine Dependent}).
+This doesn't mean @code{as} always uses the same syntax as another
+assembler for the same architecture; for example, we know of several
+incompatible versions of 680x0 assembly language syntax.
+
+Unlike older assemblers, @code{as} is designed to assemble a source
+program in one pass of the source file. This has a subtle impact on the
+@kbd{.org} directive (@pxref{Org,,@code{.org}}).
+
+@node Object Formats, Command Line, GNU Assembler, Overview
+@section Object File Formats
+
+@cindex object file format
+The GNU assembler can be configured to produce several alternative
+object file formats. For the most part, this does not affect how you
+write assembly language programs; but directives for debugging symbols
+are typically different in different file formats. @xref{Symbol
+Attributes,,Symbol Attributes}.
+
+@node Command Line, Input Files, Object Formats, Overview
+@section Command Line
+
+@cindex command line conventions
+After the program name @code{as}, the command line may contain
+options and file names. Options may appear in any order, and may be
+before, after, or between file names. The order of file names is
+significant.
+
+@cindex standard input, as input file
+@kindex --
+@file{--} (two hyphens) by itself names the standard input file
+explicitly, as one of the files for @code{as} to assemble.
+
+@cindex options, command line
+Except for @samp{--} any command line argument that begins with a
+hyphen (@samp{-}) is an option. Each option changes the behavior of
+@code{as}. No option changes the way another option works. An
+option is a @samp{-} followed by one or more letters; the case of
+the letter is important. All options are optional.
+
+Some options expect exactly one file name to follow them. The file
+name may either immediately follow the option's letter (compatible
+with older assemblers) or it may be the next command argument (GNU
+standard). These two command lines are equivalent:
+
+@smallexample
+as -o my-object-file.o mumble.s
+as -omy-object-file.o mumble.s
+@end smallexample
+
+@node Input Files, Object, Command Line, Overview
+@section Input Files
+
+@cindex input
+@cindex source program
+@cindex files, input
+We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
+describe the program input to one run of @code{as}. The program may
+be in one or more files; how the source is partitioned into files
+doesn't change the meaning of the source.
+
+@c I added "con" prefix to "catenation" just to prove I can overcome my
+@c APL training... pesch@cygnus.com
+The source program is a concatenation of the text in all the files, in the
+order specified.
+
+Each time you run @code{as} it assembles exactly one source
+program. The source program is made up of one or more files.
+(The standard input is also a file.)
+
+You give @code{as} a command line that has zero or more input file
+names. The input files are read (from left file name to right). A
+command line argument (in any position) that has no special meaning
+is taken to be an input file name.
+
+If you give @code{as} no file names it attempts to read one input file
+from the @code{as} standard input, which is normally your terminal. You
+may have to type @key{ctl-D} to tell @code{as} there is no more program
+to assemble.
+
+Use @samp{--} if you need to explicitly name the standard input file
+in your command line.
+
+If the source is empty, @code{as} will produce a small, empty object
+file.
+
+@subheading Filenames and Line-numbers
+
+@cindex input file linenumbers
+@cindex line numbers, in input files
+There are two ways of locating a line in the input file (or files) and
+either may be used in reporting error messages. One way refers to a line
+number in a physical file; the other refers to a line number in a
+``logical'' file. @xref{Errors, ,Error and Warning Messages}.
+
+@dfn{Physical files} are those files named in the command line given
+to @code{as}.
+
+@dfn{Logical files} are simply names declared explicitly by assembler
+directives; they bear no relation to physical files. Logical file names
+help error messages reflect the original source file, when @code{as}
+source is itself synthesized from other files.
+@xref{App-File,,@code{.app-file}}.
+
+@node Object, Errors, Input Files, Overview
+@section Output (Object) File
+
+@cindex object file
+@cindex output file
+@kindex a.out
+@kindex .o
+Every time you run @code{as} it produces an output file, which is
+your assembly language program translated into numbers. This file
+is the object file, named @code{a.out} unless you tell @code{as} to
+give it another name by using the @code{-o} option. Conventionally,
+object file names end with @file{.o}. The default name of
+@file{a.out} is used for historical reasons: older assemblers were
+capable of assembling self-contained programs directly into a
+runnable program.
+@c This may still work, but hasn't been tested.
+
+@cindex linker
+@kindex ld
+The object file is meant for input to the linker @code{ld}. It contains
+assembled program code, information to help @code{ld} integrate
+the assembled program into a runnable file, and (optionally) symbolic
+information for the debugger.
+
+@c link above to some info file(s) like the description of a.out.
+@c don't forget to describe GNU info as well as Unix lossage.
+
+@node Errors, , Object, Overview
+@section Error and Warning Messages
+
+@cindex error messsages
+@cindex warning messages
+@cindex messages from @code{as}
+@code{as} may write warnings and error messages to the standard error
+file (usually your terminal). This should not happen when a compiler
+runs @code{as} automatically. Warnings report an assumption made so
+that @code{as} could keep assembling a flawed program; errors report a
+grave problem that stops the assembly.
+
+@cindex format of warning messages
+Warning messages have the format
+
+@smallexample
+file_name:@b{NNN}:Warning Message Text
+@end smallexample
+
+@noindent
+@cindex line numbers, in warnings/errors
+(where @b{NNN} is a line number). If a logical file name has
+been given (@pxref{App-File,,@code{.app-file}}) it is used for the filename, otherwise the
+name of the current input file is used. If a logical line number was
+given
+(@pxref{Ln,,@code{.ln}})
+then it is used to calculate the number printed,
+otherwise the actual line in the current source file is printed. The
+message text is intended to be self explanatory (in the grand Unix
+tradition). @refill
+
+@cindex format of error messages
+Error messages have the format
+@smallexample
+file_name:@b{NNN}:FATAL:Error Message Text
+@end smallexample
+The file name and line number are derived as for warning
+messages. The actual message text may be rather less explanatory
+because many of them aren't supposed to happen.
+
+@node Invoking, Syntax, Overview, Top
+@chapter Command-Line Options
+
+@cindex options, all versions of @code{as}
+This chapter describes command-line options available in @emph{all}
+versions of the GNU assembler; @pxref{Machine Dependent}, for options specific
+to particular machine architectures.
+
+@section Enable Listings: @code{-a}, @code{-al}, @code{-as}
+
+@kindex -a
+@kindex -al
+@kindex -as
+@cindex listings, enabling
+@cindex assembly listings, enabling
+These options enable listing output from the assembler. @samp{-a} by
+itself requests all listing output; @samp{-al} requests only the
+output-program listing, and @samp{-as} requests only a symbol table
+listing.
+
+Once you have specified one of these options, you can further control
+listing output and its appearance using the directives @code{.list},
+@code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
+@code{.sbttl}.
+
+If you do not request listing output with one of the @samp{-a} options, the
+listing-control directives have no effect.
+
+@section @code{-D}
+
+@kindex -D
+This option has no effect whatsoever, but it is accepted to make it more
+likely that scripts written for other assemblers will also work with
+@code{as}.
+
+@section Work Faster: @code{-f}
+
+@kindex -f
+@cindex trusted compiler
+@cindex faster processing (@code{-f})
+@samp{-f} should only be used when assembling programs written by a
+(trusted) compiler. @samp{-f} stops the assembler from pre-processing
+the input file(s) before assembling them. @xref{Pre-processing,
+,Pre-processing}.
+
+@quotation
+@emph{Warning:} if the files actually need to be pre-processed (if they
+contain comments, for example), @code{as} will not work correctly if
+@samp{-f} is used.
+@end quotation
+
+@section @code{.include} search path: @code{-I} @var{path}
+
+@kindex -I @var{path}
+@cindex paths for @code{.include}
+@cindex search path for @code{.include}
+@cindex @code{include} directive search path
+Use this option to add a @var{path} to the list of directories
+@code{as} will search for files specified in @code{.include}
+directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
+many times as necessary to include a variety of paths. The current
+working directory is always searched first; after that, @code{as}
+searches any @samp{-I} directories in the same order as they were
+specified (left to right) on the command line.
+
+@section Difference Tables: @code{-k}
+
+@kindex -k
+
+@cindex difference tables, warning
+@cindex warning for altered difference tables
+@code{as} sometimes alters the code emitted for directives of the form
+@samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
+You can use the @samp{-k} option if you want a warning issued when this
+is done.
+
+@section Include Local Labels: @code{-L}
+
+@kindex -L
+@cindex local labels, retaining in output
+Labels beginning with @samp{L} (upper case only) are called @dfn{local
+labels}. @xref{Symbol Names}. Normally you don't see such labels when
+debugging, because they are intended for the use of programs (like
+compilers) that compose assembler programs, not for your notice.
+Normally both @code{as} and @code{ld} discard such labels, so you don't
+normally debug with them.
+
+This option tells @code{as} to retain those @samp{L@dots{}} symbols
+in the object file. Usually if you do this you also tell the linker
+@code{ld} to preserve symbols whose names begin with @samp{L}.
+
+@section Name the Object File: @code{-o}
+
+@kindex -o
+@cindex naming object file
+@cindex object file name
+There is always one object file output when you run @code{as}. By
+default it has the name @file{a.out}. You use this option (which
+takes exactly one filename) to give the object file a different name.
+
+Whatever the object file is called, @code{as} will overwrite any
+existing file of the same name.
+
+@section Join Data and Text Sections: @code{-R}
+
+@kindex -R
+@cindex data and text sections, joining
+@cindex text and data sections, joining
+@cindex joining text and data sections
+@cindex merging text and data sections
+@code{-R} tells @code{as} to write the object file as if all
+data-section data lives in the text section. This is only done at
+the very last moment: your binary data are the same, but data
+section parts are relocated differently. The data section part of
+your object file is zero bytes long because all it bytes are
+appended to the text section. (@xref{Sections,,Sections and Relocation}.)
+
+When you specify @code{-R} it would be possible to generate shorter
+address displacements (because we don't have to cross between text and
+data section). We refrain from doing this simply for compatibility with
+older versions of @code{as}. In future, @code{-R} may work this way.
+
+When @code{as} is configured for COFF output,
+this option is only useful if you use sections named @samp{.text} and
+@samp{.data}.
+
+@section Announce Version: @code{-v}
+
+@kindex -v
+@kindex -version
+@cindex @code{as} version
+@cindex version of @code{as}
+You can find out what version of as is running by including the
+option @samp{-v} (which you can also spell as @samp{-version}) on the
+command line.
+
+@section Suppress Warnings: @code{-W}
+
+@kindex -W
+@cindex suppressing warnings
+@cindex warnings, suppressing
+@code{as} should never give a warning or error message when
+assembling compiler output. But programs written by people often
+cause @code{as} to give a warning that a particular assumption was
+made. All such warnings are directed to the standard error file.
+If you use this option, no warnings are issued. This option only
+affects the warning messages: it does not change any particular of how
+@code{as} assembles your file. Errors, which stop the assembly, are
+still reported.
+
+@node Syntax, Sections, Invoking, Top
+@chapter Syntax
+
+@cindex machine-independent syntax
+@cindex syntax, machine-independent
+This chapter describes the machine-independent syntax allowed in a
+source file. @code{as} syntax is similar to what many other assemblers
+use; it is inspired in BSD 4.2
+assembler, except that @code{as} does not assemble Vax bit-fields.
+
+@menu
+* Pre-processing:: Pre-processing
+* Whitespace:: Whitespace
+* Comments:: Comments
+* Symbol Intro:: Symbols
+* Statements:: Statements
+* Constants:: Constants
+@end menu
+
+@node Pre-processing, Whitespace, Syntax, Syntax
+@section Pre-Processing
+
+@cindex preprocessing
+The pre-processor:
+@itemize @bullet
+@cindex whitespace, removed by preprocessor
+@item
+adjusts and removes extra whitespace. It leaves one space or tab before
+the keywords on a line, and turns any other whitespace on the line into
+a single space.
+
+@cindex comments, removed by preprocessor
+@item
+removes all comments, replacing them with a single space, or an
+appropriate number of newlines.
+
+@cindex constants, converted by preprocessor
+@item
+converts character constants into the appropriate numeric values.
+@end itemize
+
+Excess whitespace, comments, and character constants
+cannot be used in the portions of the input text that are not
+pre-processed.
+
+@cindex turning preprocessing on and off
+@cindex preprocessing, turning on and off
+@kindex #NO_APP
+@kindex #APP
+If the first line of an input file is @code{#NO_APP} or the @samp{-f}
+option is given, the input file will not be pre-processed. Within such
+an input file, parts of the file can be pre-processed by putting a line
+that says @code{#APP} before the text that should be pre-processed, and
+putting a line that says @code{#NO_APP} after them. This feature is
+mainly intend to support @code{asm} statements in compilers whose output
+normally does not need to be pre-processed.
+
+@node Whitespace, Comments, Pre-processing, Syntax
+@section Whitespace
+
+@cindex whitespace
+@dfn{Whitespace} is one or more blanks or tabs, in any order.
+Whitespace is used to separate symbols, and to make programs neater for
+people to read. Unless within character constants
+(@pxref{Characters,,Character Constants}), any whitespace means the same
+as exactly one space.
+
+@node Comments, Symbol Intro, Whitespace, Syntax
+@section Comments
+
+@cindex comments
+There are two ways of rendering comments to @code{as}. In both
+cases the comment is equivalent to one space.
+
+Anything from @samp{/*} through the next @samp{*/} is a comment.
+This means you may not nest these comments.
+
+@smallexample
+/*
+ The only way to include a newline ('\n') in a comment
+ is to use this sort of comment.
+*/
+
+/* This sort of comment does not nest. */
+@end smallexample
+
+@cindex line comment character
+Anything from the @dfn{line comment} character to the next newline
+is considered a comment and is ignored. The line comment character is
+@samp{#} on the Vax;
+@samp{#} on the i960;
+@samp{|} on the 680x0;
+@samp{;} for the AMD 29K family;
+@samp{;} for the machine specific family;
+@pxref{Machine Dependent}. @refill
+@c FIXME: fill in SPARC line comment char
+
+On some machines there are two different line comment characters. One
+will only begin a comment if it is the first non-whitespace character on
+a line, while the other will always begin a comment.
+
+@kindex #
+@cindex lines starting with @code{#}
+@cindex logical line numbers
+To be compatible with past assemblers, a special interpretation is
+given to lines that begin with @samp{#}. Following the @samp{#} an
+absolute expression (@pxref{Expressions}) is expected: this will be
+the logical line number of the @b{next} line. Then a string
+(@xref{Strings}.) is allowed: if present it is a new logical file
+name. The rest of the line, if any, should be whitespace.
+
+If the first non-whitespace characters on the line are not numeric,
+the line is ignored. (Just like a comment.)
+@smallexample
+ # This is an ordinary comment.
+# 42-6 "new_file_name" # New logical file name
+ # This is logical line # 36.
+@end smallexample
+This feature is deprecated, and may disappear from future versions
+of @code{as}.
+
+@node Symbol Intro, Statements, Comments, Syntax
+@section Symbols
+
+@cindex symbols
+@cindex characters used in symbols
+A @dfn{symbol} is one or more characters chosen from the set of all
+letters (both upper and lower case), digits and
+the two characters @samp{_.}
+On most machines, you can also use @code{$} in symbol names; exceptions
+are noted in @ref{Machine Dependent}.
+No symbol may begin with a digit. Case is significant.
+There is no length limit: all characters are significant. Symbols are
+delimited by characters not in that set, or by the beginning of a file
+(since the source program must end with a newline, the end of a file is
+not a possible symbol delimiter). @xref{Symbols}.
+@cindex length of symbols
+
+@node Statements, Constants, Symbol Intro, Syntax
+@section Statements
+
+@cindex statements, structure of
+@cindex line separator character
+@cindex statement separator character
+A @dfn{statement} ends at a newline character (@samp{\n}) or line
+separator character. (The line separator is usually @samp{;}, unless
+this conflicts with the comment character; @pxref{Machine Dependent}.) The
+newline or separator character is considered part of the preceding
+statement. Newlines and separators within character constants are an
+exception: they don't end statements.
+
+@cindex newline, required at file end
+@cindex EOF, newline must precede
+It is an error to end any statement with end-of-file: the last
+character of any input file should be a newline.@refill
+
+@cindex continuing statements
+@cindex multi-line statements
+@cindex statement on multiple lines
+You may write a statement on more than one line if you put a
+backslash (@kbd{\}) immediately in front of any newlines within the
+statement. When @code{as} reads a backslashed newline both
+characters are ignored. You can even put backslashed newlines in
+the middle of symbol names without changing the meaning of your
+source program.
+
+An empty statement is allowed, and may include whitespace. It is ignored.
+
+@cindex instructions and directives
+@cindex directives and instructions
+@c "key symbol" is not used elsewhere in the document; seems pedantic to
+@c @defn{} it in that case, as was done previously... pesch@cygnus.com,
+@c 13feb91.
+A statement begins with zero or more labels, optionally followed by a
+key symbol which determines what kind of statement it is. The key
+symbol determines the syntax of the rest of the statement. If the
+symbol begins with a dot @samp{.} then the statement is an assembler
+directive: typically valid for any computer. If the symbol begins with
+a letter the statement is an assembly language @dfn{instruction}: it
+will assemble into a machine language instruction.
+Different versions of @code{as} for different computers will
+recognize different instructions. In fact, the same symbol may
+represent a different instruction in a different computer's assembly
+language.@refill
+
+@cindex @code{:} (label)
+@cindex label (@code{:})
+A label is a symbol immediately followed by a colon (@code{:}).
+Whitespace before a label or after a colon is permitted, but you may not
+have whitespace between a label's symbol and its colon. @xref{Labels}.
+
+@smallexample
+label: .directive followed by something
+another_label: # This is an empty statement.
+ instruction operand_1, operand_2, @dots{}
+@end smallexample
+
+@node Constants, , Statements, Syntax
+@section Constants
+
+@cindex constants
+A constant is a number, written so that its value is known by
+inspection, without knowing any context. Like this:
+@smallexample
+.byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
+.ascii "Ring the bell\7" # A string constant.
+.octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
+.float 0f-314159265358979323846264338327\
+95028841971.693993751E-40 # - pi, a flonum.
+@end smallexample
+
+@menu
+* Characters:: Character Constants
+* Numbers:: Number Constants
+@end menu
+
+@node Characters, Numbers, Constants, Constants
+@subsection Character Constants
+
+@cindex character constants
+@cindex constants, character
+There are two kinds of character constants. A @dfn{character} stands
+for one character in one byte and its value may be used in
+numeric expressions. String constants (properly called string
+@emph{literals}) are potentially many bytes and their values may not be
+used in arithmetic expressions.
+
+@menu
+* Strings:: Strings
+* Chars:: Characters
+@end menu
+
+@node Strings, Chars, Characters, Characters
+@subsubsection Strings
+
+@cindex string constants
+@cindex constants, string
+A @dfn{string} is written between double-quotes. It may contain
+double-quotes or null characters. The way to get special characters
+into a string is to @dfn{escape} these characters: precede them with
+a backslash @samp{\} character. For example @samp{\\} represents
+one backslash: the first @code{\} is an escape which tells
+@code{as} to interpret the second character literally as a backslash
+(which prevents @code{as} from recognizing the second @code{\} as an
+escape character). The complete list of escapes follows.
+
+@cindex escape codes, character
+@cindex character escape codes
+@table @kbd
+@c @item \a
+@c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
+@c
+@item \b
+@cindex @code{\b} (backspace character)
+@cindex backspace (@code{\b})
+Mnemonic for backspace; for ASCII this is octal code 010.
+
+@c @item \e
+@c Mnemonic for EOText; for ASCII this is octal code 004.
+@c
+@item \f
+@cindex @code{\f} (formfeed character)
+@cindex formfeed (@code{\f})
+Mnemonic for FormFeed; for ASCII this is octal code 014.
+
+@item \n
+@cindex @code{\n} (newline character)
+@cindex newline (@code{\n})
+Mnemonic for newline; for ASCII this is octal code 012.
+
+@c @item \p
+@c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
+@c
+@item \r
+@cindex @code{\r} (carriage return character)
+@cindex carriage return (@code{\r})
+Mnemonic for carriage-Return; for ASCII this is octal code 015.
+
+@c @item \s
+@c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
+@c other assemblers.
+@c
+@item \t
+@cindex @code{\t} (tab)
+@cindex tab (@code{\t})
+Mnemonic for horizontal Tab; for ASCII this is octal code 011.
+
+@c @item \v
+@c Mnemonic for Vertical tab; for ASCII this is octal code 013.
+@c @item \x @var{digit} @var{digit} @var{digit}
+@c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
+@c
+@item \ @var{digit} @var{digit} @var{digit}
+@cindex @code{\@var{ddd}} (octal character code)
+@cindex octal character code (@code{\@var{ddd}})
+An octal character code. The numeric code is 3 octal digits.
+For compatibility with other Unix systems, 8 and 9 are accepted as digits:
+for example, @code{\008} has the value 010, and @code{\009} the value 011.
+
+@item \\
+@cindex @code{\\} (@samp{\} character)
+@cindex backslash (@code{\\})
+Represents one @samp{\} character.
+
+@c @item \'
+@c Represents one @samp{'} (accent acute) character.
+@c This is needed in single character literals
+@c (@xref{Characters,,Character Constants}.) to represent
+@c a @samp{'}.
+@c
+@item \"
+@cindex @code{\"} (doublequote character)
+@cindex doublequote (@code{\"})
+Represents one @samp{"} character. Needed in strings to represent
+this character, because an unescaped @samp{"} would end the string.
+
+@item \ @var{anything-else}
+Any other character when escaped by @kbd{\} will give a warning, but
+assemble as if the @samp{\} was not present. The idea is that if
+you used an escape sequence you clearly didn't want the literal
+interpretation of the following character. However @code{as} has no
+other interpretation, so @code{as} knows it is giving you the wrong
+code and warns you of the fact.
+@end table
+
+Which characters are escapable, and what those escapes represent,
+varies widely among assemblers. The current set is what we think
+the BSD 4.2 assembler recognizes, and is a subset of what most C
+compilers recognize. If you are in doubt, don't use an escape
+sequence.
+
+@node Chars, , Strings, Characters
+@subsubsection Characters
+
+@cindex single character constant
+@cindex character, single
+@cindex constant, single character
+A single character may be written as a single quote immediately
+followed by that character. The same escapes apply to characters as
+to strings. So if you want to write the character backslash, you
+must write @kbd{'\\} where the first @code{\} escapes the second
+@code{\}. As you can see, the quote is an acute accent, not a
+grave accent. A newline
+immediately following an acute accent is taken as a literal character
+and does not count as the end of a statement. The value of a character
+constant in a numeric expression is the machine's byte-wide code for
+that character. @code{as} assumes your character code is ASCII:
+@kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
+
+@node Numbers, , Characters, Constants
+@subsection Number Constants
+
+@cindex constants, number
+@cindex number constants
+@code{as} distinguishes three kinds of numbers according to how they
+are stored in the target machine. @emph{Integers} are numbers that
+would fit into an @code{int} in the C language. @emph{Bignums} are
+integers, but they are stored in more than 32 bits. @emph{Flonums}
+are floating point numbers, described below.
+
+@menu
+* Integers:: Integers
+* Bignums:: Bignums
+* Flonums:: Flonums
+@end menu
+
+@node Integers, Bignums, Numbers, Numbers
+@subsubsection Integers
+@cindex integers
+@cindex constants, integer
+
+@cindex binary integers
+@cindex integers, binary
+A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
+the binary digits @samp{01}.
+
+@cindex octal integers
+@cindex integers, octal
+An octal integer is @samp{0} followed by zero or more of the octal
+digits (@samp{01234567}).
+
+@cindex decimal integers
+@cindex integers, decimal
+A decimal integer starts with a non-zero digit followed by zero or
+more digits (@samp{0123456789}).
+
+@cindex hexadecimal integers
+@cindex integers, hexadecimal
+A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
+more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
+
+Integers have the usual values. To denote a negative integer, use
+the prefix operator @samp{-} discussed under expressions
+(@pxref{Prefix Ops,,Prefix Operators}).
+
+@node Bignums, Flonums, Integers, Numbers
+@subsubsection Bignums
+
+@cindex bignums
+@cindex constants, bignum
+A @dfn{bignum} has the same syntax and semantics as an integer
+except that the number (or its negative) takes more than 32 bits to
+represent in binary. The distinction is made because in some places
+integers are permitted while bignums are not.
+
+@node Flonums, , Bignums, Numbers
+@subsubsection Flonums
+@cindex flonums
+@cindex floating point numbers
+@cindex constants, floating point
+
+@cindex precision, floating point
+A @dfn{flonum} represents a floating point number. The translation is
+indirect: a decimal floating point number from the text is converted by
+@code{as} to a generic binary floating point number of more than
+sufficient precision. This generic floating point number is converted
+to a particular computer's floating point format (or formats) by a
+portion of @code{as} specialized to that computer.
+
+A flonum is written by writing (in order)
+@itemize @bullet
+@item
+The digit @samp{0}.
+@item
+A letter, to tell @code{as} the rest of the number is a flonum.
+@kbd{e} is recommended. Case is not important.
+@ignore
+@c FIXME: verify if flonum syntax really this vague for most cases
+ (Any otherwise illegal letter
+will work here, but that might be changed. Vax BSD 4.2 assembler seems
+to allow any of @samp{defghDEFGH}.)
+@end ignore
+On the AMD 29K and H8/300 architectures, the letter must be:
+One of the letters @samp{DFPRSX} (in upper or lower case).
+On the Intel 960 architecture, the letter must be:
+One of the letters @samp{DFT} (in upper or lower case).
+@item
+An optional sign: either @samp{+} or @samp{-}.
+@item
+An optional @dfn{integer part}: zero or more decimal digits.
+@item
+An optional @dfn{fractional part}: @samp{.} followed by zero
+or more decimal digits.
+@item
+An optional exponent, consisting of:
+@itemize @bullet
+@item
+An @samp{E} or @samp{e}.
+@c I can't find a config where "EXP_CHARS" is other than 'eE', but in
+@c principle this can perfectly well be different on different targets.
+@item
+Optional sign: either @samp{+} or @samp{-}.
+@item
+One or more decimal digits.
+@end itemize
+@end itemize
+
+At least one of the integer part or the fractional part must be
+present. The floating point number has the usual base-10 value.
+
+@code{as} does all processing using integers. Flonums are computed
+independently of any floating point hardware in the computer running
+@code{as}.
+
+
+@node Sections, Symbols, Syntax, Top
+@chapter Sections and Relocation
+@cindex sections
+@cindex relocation
+
+@menu
+* Secs Background:: Background
+* ld Sections:: ld Sections
+* as Sections:: as Internal Sections
+* Sub-Sections:: Sub-Sections
+* bss:: bss Section
+@end menu
+
+@node Secs Background, ld Sections, Sections, Sections
+@section Background
+
+Roughly, a section is a range of addresses, with no gaps; all data
+``in'' those addresses is treated the same for some particular purpose.
+For example there may be a ``read only'' section.
+
+@cindex linker, and assembler
+@cindex assembler, and linker
+The linker @code{ld} reads many object files (partial programs) and
+combines their contents to form a runnable program. When @code{as}
+emits an object file, the partial program is assumed to start at address
+0. @code{ld} will assign the final addresses the partial program
+occupies, so that different partial programs don't overlap. This is
+actually an over-simplification, but it will suffice to explain how
+@code{as} uses sections.
+
+@code{ld} moves blocks of bytes of your program to their run-time
+addresses. These blocks slide to their run-time addresses as rigid
+units; their length does not change and neither does the order of bytes
+within them. Such a rigid unit is called a @emph{section}. Assigning
+run-time addresses to sections is called @dfn{relocation}. It includes
+the task of adjusting mentions of object-file addresses so they refer to
+the proper run-time addresses.
+For the H8/300, @code{as} pads sections if needed to ensure they end
+on a word (sixteen bit) boundary.
+
+@cindex standard @code{as} sections
+An object file written by @code{as} has at least three sections, any
+of which may be empty. These are named @dfn{text}, @dfn{data} and
+@dfn{bss} sections.
+
+When it generates COFF output,
+@code{as} can also generate whatever other named sections you specify
+using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
+If you don't use any directives that place output in the @samp{.text}
+or @samp{.data} sections, these sections will still exist, but will be empty.
+
+Within the object file, the text section starts at address @code{0}, the
+data section follows, and the bss section follows the data section.
+
+To let @code{ld} know which data will change when the sections are
+relocated, and how to change that data, @code{as} also writes to the
+object file details of the relocation needed. To perform relocation
+@code{ld} must know, each time an address in the object
+file is mentioned:
+@itemize @bullet
+@item
+Where in the object file is the beginning of this reference to
+an address?
+@item
+How long (in bytes) is this reference?
+@item
+Which section does the address refer to? What is the numeric value of
+@display
+(@var{address}) @minus{} (@var{start-address of section})?
+@end display
+@item
+Is the reference to an address ``Program-Counter relative''?
+@end itemize
+
+@cindex addresses, format of
+@cindex section-relative addressing
+In fact, every address @code{as} ever uses is expressed as
+@display
+(@var{section}) + (@var{offset into section})
+@end display
+@noindent
+Further, every expression @code{as} computes is of this section-relative
+nature. @dfn{Absolute expression} means an expression with section
+``absolute'' (@pxref{ld Sections}). A @dfn{pass1 expression} means
+an expression with section ``pass1'' (@pxref{as Sections,,as
+Internal Sections}). In this manual we use the notation @{@var{secname}
+@var{N}@} to mean ``offset @var{N} into section @var{secname}''.
+
+Apart from text, data and bss sections you need to know about the
+@dfn{absolute} section. When @code{ld} mixes partial programs,
+addresses in the absolute section remain unchanged. For example, address
+@code{@{absolute 0@}} is ``relocated'' to run-time address 0 by @code{ld}.
+Although two partial programs' data sections will not overlap addresses
+after linking, @emph{by definition} their absolute sections will overlap.
+Address @code{@{absolute@ 239@}} in one partial program will always be the same
+address when the program is running as address @code{@{absolute@ 239@}} in any
+other partial program.
+
+The idea of sections is extended to the @dfn{undefined} section. Any
+address whose section is unknown at assembly time is by definition
+rendered @{undefined @var{U}@}---where @var{U} will be filled in later.
+Since numbers are always defined, the only way to generate an undefined
+address is to mention an undefined symbol. A reference to a named
+common block would be such a symbol: its value is unknown at assembly
+time so it has section @emph{undefined}.
+
+By analogy the word @emph{section} is used to describe groups of sections in
+the linked program. @code{ld} puts all partial programs' text
+sections in contiguous addresses in the linked program. It is
+customary to refer to the @emph{text section} of a program, meaning all
+the addresses of all partial program's text sections. Likewise for
+data and bss sections.
+
+Some sections are manipulated by @code{ld}; others are invented for
+use of @code{as} and have no meaning except during assembly.
+
+@node ld Sections, as Sections, Secs Background, Sections
+@section ld Sections
+@code{ld} deals with just four kinds of sections, summarized below.
+
+@table @strong
+
+@cindex named sections
+@cindex sections, named
+@item named sections
+@cindex text section
+@cindex data section
+@item text section
+@itemx data section
+These sections hold your program. @code{as} and @code{ld} treat them as
+separate but equal sections. Anything you can say of one section is
+true another.
+When the program is running, however, it is
+customary for the text section to be unalterable. The
+text section is often shared among processes: it will contain
+instructions, constants and the like. The data section of a running
+program is usually alterable: for example, C variables would be stored
+in the data section.
+
+@cindex bss section
+@item bss section
+This section contains zeroed bytes when your program begins running. It
+is used to hold unitialized variables or common storage. The length of
+each partial program's bss section is important, but because it starts
+out containing zeroed bytes there is no need to store explicit zero
+bytes in the object file. The bss section was invented to eliminate
+those explicit zeros from object files.
+
+@cindex absolute section
+@item absolute section
+Address 0 of this section is always ``relocated'' to runtime address 0.
+This is useful if you want to refer to an address that @code{ld} must
+not change when relocating. In this sense we speak of absolute
+addresses being ``unrelocatable'': they don't change during relocation.
+
+@cindex undefined section
+@item undefined section
+This ``section'' is a catch-all for address references to objects not in
+the preceding sections.
+@c FIXME: ref to some other doc on obj-file formats could go here.
+@end table
+
+@cindex relocation example
+An idealized example of three relocatable sections follows.
+The example uses the traditional section names @samp{.text} and @samp{.data}.
+Memory addresses are on the horizontal axis.
+
+@c TEXI2ROFF-KILL
+@ifinfo
+@c END TEXI2ROFF-KILL
+@smallexample
+ +-----+----+--+
+partial program # 1: |ttttt|dddd|00|
+ +-----+----+--+
+
+ text data bss
+ seg. seg. seg.
+
+ +---+---+---+
+partial program # 2: |TTT|DDD|000|
+ +---+---+---+
+
+ +--+---+-----+--+----+---+-----+~~
+linked program: | |TTT|ttttt| |dddd|DDD|00000|
+ +--+---+-----+--+----+---+-----+~~
+
+ addresses: 0 @dots{}
+@end smallexample
+@c TEXI2ROFF-KILL
+@end ifinfo
+@c FIXME make sure no page breaks inside figure!!
+@tex
+
+\line{\it Partial program \#1: \hfil}
+\line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
+\line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
+
+\line{\it Partial program \#2: \hfil}
+\line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
+\line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
+
+\line{\it linked program: \hfil}
+\line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
+\line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
+ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
+DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
+
+\line{\it addresses: \hfil}
+\line{0\dots\hfil}
+
+@end tex
+@c END TEXI2ROFF-KILL
+
+@node as Sections, Sub-Sections, ld Sections, Sections
+@section as Internal Sections
+
+@cindex internal @code{as} sections
+@cindex sections in messages, internal
+These sections are meant only for the internal use of @code{as}. They
+have no meaning at run-time. You don't really need to know about these
+sections for most purposes; but they can be mentioned in @code{as}
+warning messages, so it might be helpful to have an idea of their
+meanings to @code{as}. These sections are used to permit the
+value of every expression in your assembly language program to be a
+section-relative address.
+
+@table @b
+@item absent
+@cindex absent (internal section)
+An expression was expected and none was found.
+
+@item ASSEMBLER-INTERNAL-LOGIC-ERROR!
+@cindex assembler internal logic error
+An internal assembler logic error has been found. This means there is a
+bug in the assembler.
+
+@item bignum/flonum
+@cindex bignum/flonum (internal section)
+If a number can't be written as a C @code{int} constant (a bignum or a
+flonum, but not an integer), it is recorded as belonging to this
+``section''. @code{as} has to remember that a flonum or a bignum
+does not fit into 32 bits, and cannot be an argument (@pxref{Arguments})
+in an expression: this is done by making a flonum or bignum be in a
+separate internal section. This is purely for internal @code{as}
+convenience; bignum/flonum section behaves similarly to absolute
+section.
+
+@item pass1 section
+@cindex pass1 (internal section)
+The expression was impossible to evaluate in the first pass. The
+assembler will attempt a second pass (second reading of the source) to
+evaluate the expression. Your expression mentioned an undefined symbol
+in a way that defies the one-pass (section + offset in section) assembly
+process. No compiler need emit such an expression.
+
+@quotation
+@emph{Warning:} the second pass is currently not implemented. @code{as}
+will abort with an error message if one is required.
+@end quotation
+
+@item difference section
+@cindex difference (internal section)
+As an assist to the C compiler, expressions of the forms
+@display
+ (@var{undefined symbol}) @minus{} (@var{expression})
+ @var{something} @minus{} (@var{undefined symbol})
+ (@var{undefined symbol}) @minus{} (@var{undefined symbol})
+@end display
+
+are permitted, and belong to the difference section. @code{as}
+re-evaluates such expressions after the source file has been read and
+the symbol table built. If by that time there are no undefined symbols
+in the expression then the expression assumes a new section. The
+intention is to permit statements like
+@samp{.word label - base_of_table}
+to be assembled in one pass where both @code{label} and
+@code{base_of_table} are undefined. This is useful for compiling C and
+Algol switch statements, Pascal case statements, FORTRAN computed goto
+statements and the like.
+@c FIXME item debug
+@c FIXME item transfer[t] vector preload
+@c FIXME item transfer[t] vector postload
+@c FIXME item register
+@end table
+
+@node Sub-Sections, bss, as Sections, Sections
+@section Sub-Sections
+
+@cindex numbered subsections
+@cindex grouping data
+Assembled bytes
+conventionally
+fall into two sections: text and data.
+You may have separate groups of
+data in named sections
+that you want to end up near to each other in the object
+file, even though they are not contiguous in the assembler source.
+@code{as} allows you to use @dfn{subsections} for this purpose.
+Within each section, there can be numbered subsections with
+values from 0 to 8192. Objects assembled into the same subsection will
+be grouped with other objects in the same subsection when they are all
+put into the object file. For example, a compiler might want to store
+constants in the text section, but might not want to have them
+interspersed with the program being assembled. In this case, the
+compiler could issue a @samp{.text 0} before each section of code being
+output, and a @samp{.text 1} before each group of constants being output.
+
+Subsections are optional. If you don't use subsections, everything
+will be stored in subsection number zero.
+
+Each subsection is zero-padded up to a multiple of four bytes.
+(Subsections may be padded a different amount on different flavors
+of @code{as}.)
+
+Subsections appear in your object file in numeric order, lowest numbered
+to highest. (All this to be compatible with other people's assemblers.)
+The object file contains no representation of subsections; @code{ld} and
+other programs that manipulate object files will see no trace of them.
+They just see all your text subsections as a text section, and all your
+data subsections as a data section.
+
+To specify which subsection you want subsequent statements assembled
+into, use a numeric argument to specify it, in a @samp{.text
+@var{expression}} or a @samp{.data @var{expression}} statement.
+When generating COFF output, you
+can also use an extra subsection
+argument with arbitrary named sections: @samp{.section @var{name},
+@var{expression}}.
+@var{Expression} should be an absolute expression.
+(@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
+is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
+begins in @code{text 0}. For instance:
+@smallexample
+.text 0 # The default subsection is text 0 anyway.
+.ascii "This lives in the first text subsection. *"
+.text 1
+.ascii "But this lives in the second text subsection."
+.data 0
+.ascii "This lives in the data section,"
+.ascii "in the first data subsection."
+.text 0
+.ascii "This lives in the first text section,"
+.ascii "immediately following the asterisk (*)."
+@end smallexample
+
+Each section has a @dfn{location counter} incremented by one for every
+byte assembled into that section. Because subsections are merely a
+convenience restricted to @code{as} there is no concept of a subsection
+location counter. There is no way to directly manipulate a location
+counter---but the @code{.align} directive will change it, and any label
+definition will capture its current value. The location counter of the
+section that statements are being assembled into is said to be the
+@dfn{active} location counter.
+
+@node bss, , Sub-Sections, Sections
+@section bss Section
+
+@cindex bss section
+@cindex common variable storage
+The bss section is used for local common variable storage.
+You may allocate address space in the bss section, but you may
+not dictate data to load into it before your program executes. When
+your program starts running, all the contents of the bss
+section are zeroed bytes.
+
+Addresses in the bss section are allocated with special directives; you
+may not assemble anything directly into the bss section. Hence there
+are no bss subsections. @xref{Comm,,@code{.comm}},
+@pxref{Lcomm,,@code{.lcomm}}.
+
+@node Symbols, Expressions, Sections, Top
+@chapter Symbols
+
+@cindex symbols
+Symbols are a central concept: the programmer uses symbols to name
+things, the linker uses symbols to link, and the debugger uses symbols
+to debug.
+
+@quotation
+@cindex debuggers, and symbol order
+@emph{Warning:} @code{as} does not place symbols in the object file in
+the same order they were declared. This may break some debuggers.
+@end quotation
+
+@menu
+* Labels:: Labels
+* Setting Symbols:: Giving Symbols Other Values
+* Symbol Names:: Symbol Names
+* Dot:: The Special Dot Symbol
+* Symbol Attributes:: Symbol Attributes
+@end menu
+
+@node Labels, Setting Symbols, Symbols, Symbols
+@section Labels
+
+@cindex labels
+A @dfn{label} is written as a symbol immediately followed by a colon
+@samp{:}. The symbol then represents the current value of the
+active location counter, and is, for example, a suitable instruction
+operand. You are warned if you use the same symbol to represent two
+different locations: the first definition overrides any other
+definitions.
+
+@node Setting Symbols, Symbol Names, Labels, Symbols
+@section Giving Symbols Other Values
+
+@cindex assigning values to symbols
+@cindex symbol values, assigning
+A symbol can be given an arbitrary value by writing a symbol, followed
+by an equals sign @samp{=}, followed by an expression
+(@pxref{Expressions}). This is equivalent to using the @code{.set}
+directive. @xref{Set,,@code{.set}}.
+
+@node Symbol Names, Dot, Setting Symbols, Symbols
+@section Symbol Names
+
+@cindex symbol names
+@cindex names, symbol
+Symbol names begin with a letter or with one of
+@samp{_.}
+(On most machines, you can also use @code{$} in symbol names; exceptions
+are noted in @ref{Machine Dependent}.)
+That character may be followed by any string of digits, letters,
+dollar signs (unless otherwise noted in @ref{Machine Dependent}),
+and underscores.
+Case of letters is significant:
+@code{foo} is a different symbol name than @code{Foo}.
+
+For the AMD 29K family, @samp{?} is also allowed in the
+body of a symbol name, though not at its beginning.
+
+Each symbol has exactly one name. Each name in an assembly language
+program refers to exactly one symbol. You may use that symbol name any
+number of times in a program.
+
+@subheading Local Symbol Names
+
+@cindex local symbol names
+@cindex symbol names, local
+@cindex temporary symbol names
+@cindex symbol names, temporary
+Local symbols help compilers and programmers use names temporarily.
+There are ten local symbol names, which are re-used throughout the
+program. You may refer to them using the names @samp{0} @samp{1}
+@dots{} @samp{9}. To define a local symbol, write a label of the form
+@samp{@b{N}:} (where @b{N} represents any digit). To refer to the most
+recent previous definition of that symbol write @samp{@b{N}b}, using the
+same digit as when you defined the label. To refer to the next
+definition of a local label, write @samp{@b{N}f}---where @b{N} gives you
+a choice of 10 forward references. The @samp{b} stands for
+``backwards'' and the @samp{f} stands for ``forwards''.
+
+Local symbols are not emitted by the current GNU C compiler.
+
+There is no restriction on how you can use these labels, but
+remember that at any point in the assembly you can refer to at most
+10 prior local labels and to at most 10 forward local labels.
+
+Local symbol names are only a notation device. They are immediately
+transformed into more conventional symbol names before the assembler
+uses them. The symbol names stored in the symbol table, appearing in
+error messages and optionally emitted to the object file have these
+parts:
+
+@table @code
+@item L
+All local labels begin with @samp{L}. Normally both @code{as} and
+@code{ld} forget symbols that start with @samp{L}. These labels are
+used for symbols you are never intended to see. If you give the
+@samp{-L} option then @code{as} will retain these symbols in the
+object file. If you also instruct @code{ld} to retain these symbols,
+you may use them in debugging.
+
+@item @var{digit}
+If the label is written @samp{0:} then the digit is @samp{0}.
+If the label is written @samp{1:} then the digit is @samp{1}.
+And so on up through @samp{9:}.
+
+@item @ctrl{A}
+This unusual character is included so you don't accidentally invent
+a symbol of the same name. The character has ASCII value
+@samp{\001}.
+
+@item @emph{ordinal number}
+This is a serial number to keep the labels distinct. The first
+@samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the
+number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:}
+through @samp{9:}.
+@end table
+
+For instance, the first @code{1:} is named @code{L1@ctrl{A}1}, the 44th
+@code{3:} is named @code{L3@ctrl{A}44}.
+
+@node Dot, Symbol Attributes, Symbol Names, Symbols
+@section The Special Dot Symbol
+
+@cindex dot (symbol)
+@cindex @code{.} (symbol)
+@cindex current address
+@cindex location counter
+The special symbol @samp{.} refers to the current address that
+@code{as} is assembling into. Thus, the expression @samp{melvin:
+.long .} will cause @code{melvin} to contain its own address.
+Assigning a value to @code{.} is treated the same as a @code{.org}
+directive. Thus, the expression @samp{.=.+4} is the same as saying
+@samp{.block 4}.
+
+@node Symbol Attributes, , Dot, Symbols
+@section Symbol Attributes
+
+@cindex symbol attributes
+@cindex attributes, symbol
+Every symbol has, as well as its name, the attributes ``Value'' and
+``Type''. Depending on output format, symbols can also have auxiliary
+attributes.
+
+If you use a symbol without defining it, @code{as} assumes zero for
+all these attributes, and probably won't warn you. This makes the
+symbol an externally defined symbol, which is generally what you
+would want.
+
+@menu
+* Symbol Value:: Value
+* Symbol Type:: Type
+* a.out Symbols:: Symbol Attributes: @code{a.out}
+* COFF Symbols:: Symbol Attributes for COFF
+@end menu
+
+@node Symbol Value, Symbol Type, Symbol Attributes, Symbol Attributes
+@subsection Value
+
+@cindex value of a symbol
+@cindex symbol value
+The value of a symbol is (usually) 32 bits. For a symbol which labels a
+location in the text, data, bss or absolute sections the value is the
+number of addresses from the start of that section to the label.
+Naturally for text, data and bss sections the value of a symbol changes
+as @code{ld} changes section base addresses during linking. Absolute
+symbols' values do not change during linking: that is why they are
+called absolute.
+
+The value of an undefined symbol is treated in a special way. If it is
+0 then the symbol is not defined in this assembler source program, and
+@code{ld} will try to determine its value from other programs it is
+linked with. You make this kind of symbol simply by mentioning a symbol
+name without defining it. A non-zero value represents a @code{.comm}
+common declaration. The value is how much common storage to reserve, in
+bytes (addresses). The symbol refers to the first address of the
+allocated storage.
+
+@node Symbol Type, a.out Symbols, Symbol Value, Symbol Attributes
+@subsection Type
+
+@cindex type of a symbol
+@cindex symbol type
+The type attribute of a symbol contains relocation (section)
+information, any flag settings indicating that a symbol is external, and
+(optionally), other information for linkers and debuggers. The exact
+format depends on the object-code output format in use.
+
+@node a.out Symbols, COFF Symbols, Symbol Type, Symbol Attributes
+@subsection Symbol Attributes: @code{a.out}
+
+@cindex @code{a.out} symbol attributes
+@cindex symbol attributes, @code{a.out}
+
+@menu
+* Symbol Desc:: Descriptor
+* Symbol Other:: Other
+@end menu
+
+@node Symbol Desc, Symbol Other, a.out Symbols, a.out Symbols
+@subsubsection Descriptor
+
+@cindex descriptor, of @code{a.out} symbol
+This is an arbitrary 16-bit value. You may establish a symbol's
+descriptor value by using a @code{.desc} statement
+(@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
+@code{as}.
+
+@node Symbol Other, , Symbol Desc, a.out Symbols
+@subsubsection Other
+
+@cindex other attribute, of @code{a.out} symbol
+This is an arbitrary 8-bit value. It means nothing to @code{as}.
+
+@node COFF Symbols, , a.out Symbols, Symbol Attributes
+@subsection Symbol Attributes for COFF
+
+@cindex COFF symbol attributes
+@cindex symbol attributes, COFF
+
+The COFF format supports a multitude of auxiliary symbol attributes;
+like the primary symbol attributes, they are set between @code{.def} and
+@code{.endef} directives.
+
+@subsubsection Primary Attributes
+
+@cindex primary attributes, COFF symbols
+The symbol name is set with @code{.def}; the value and type,
+respectively, with @code{.val} and @code{.type}.
+
+@subsubsection Auxiliary Attributes
+
+@cindex auxiliary attributes, COFF symbols
+The @code{as} directives @code{.dim}, @code{.line}, @code{.scl},
+@code{.size}, and @code{.tag} can generate auxiliary symbol table
+information for COFF.
+
+@node Expressions, Pseudo Ops, Symbols, Top
+@chapter Expressions
+
+@cindex expressions
+@cindex addresses
+@cindex numeric values
+An @dfn{expression} specifies an address or numeric value.
+Whitespace may precede and/or follow an expression.
+
+@menu
+* Empty Exprs:: Empty Expressions
+* Integer Exprs:: Integer Expressions
+@end menu
+
+@node Empty Exprs, Integer Exprs, Expressions, Expressions
+@section Empty Expressions
+
+@cindex empty expressions
+@cindex expressions, empty
+An empty expression has no value: it is just whitespace or null.
+Wherever an absolute expression is required, you may omit the
+expression and @code{as} will assume a value of (absolute) 0. This
+is compatible with other assemblers.
+
+@node Integer Exprs, , Empty Exprs, Expressions
+@section Integer Expressions
+
+@cindex integer expressions
+@cindex expressions, integer
+An @dfn{integer expression} is one or more @emph{arguments} delimited
+by @emph{operators}.
+
+@menu
+* Arguments:: Arguments
+* Operators:: Operators
+* Prefix Ops:: Prefix Operators
+* Infix Ops:: Infix Operators
+@end menu
+
+@node Arguments, Operators, Integer Exprs, Integer Exprs
+@subsection Arguments
+
+@cindex expression arguments
+@cindex arguments in expressions
+@cindex operands in expressions
+@cindex arithmetic operands
+@dfn{Arguments} are symbols, numbers or subexpressions. In other
+contexts arguments are sometimes called ``arithmetic operands''. In
+this manual, to avoid confusing them with the ``instruction operands'' of
+the machine language, we use the term ``argument'' to refer to parts of
+expressions only, reserving the word ``operand'' to refer only to machine
+instruction operands.
+
+Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
+@var{section} is one of text, data, bss, absolute,
+or undefined. @var{NNN} is a signed, 2's complement 32 bit
+integer.
+
+Numbers are usually integers.
+
+A number can be a flonum or bignum. In this case, you are warned
+that only the low order 32 bits are used, and @code{as} pretends
+these 32 bits are an integer. You may write integer-manipulating
+instructions that act on exotic constants, compatible with other
+assemblers.
+
+@cindex subexpressions
+Subexpressions are a left parenthesis @samp{(} followed by an integer
+expression, followed by a right parenthesis @samp{)}; or a prefix
+operator followed by an argument.
+
+@node Operators, Prefix Ops, Arguments, Integer Exprs
+@subsection Operators
+
+@cindex operators, in expressions
+@cindex arithmetic functions
+@cindex functions, in expressions
+@dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
+operators are followed by an argument. Infix operators appear
+between their arguments. Operators may be preceded and/or followed by
+whitespace.
+
+@node Prefix Ops, Infix Ops, Operators, Integer Exprs
+@subsection Prefix Operator
+
+@cindex prefix operators
+@code{as} has the following @dfn{prefix operators}. They each take
+one argument, which must be absolute.
+
+@c the tex/end tex stuff surrounding this small table is meant to make
+@c it align, on the printed page, with the similar table in the next
+@c section (which is inside an enumerate).
+@tex
+\global\advance\leftskip by \itemindent
+@end tex
+
+@table @code
+@item -
+@dfn{Negation}. Two's complement negation.
+@item ~
+@dfn{Complementation}. Bitwise not.
+@end table
+
+@tex
+\global\advance\leftskip by -\itemindent
+@end tex
+
+@node Infix Ops, , Prefix Ops, Integer Exprs
+@subsection Infix Operators
+
+@cindex infix operators
+@cindex operators, permitted arguments
+@dfn{Infix operators} take two arguments, one on either side. Operators
+have precedence, but operations with equal precedence are performed left
+to right. Apart from @code{+} or @code{-}, both arguments must be
+absolute, and the result is absolute.
+
+@enumerate
+@cindex operator precedence
+@cindex precedence of operators
+
+@item
+Highest Precedence
+
+@table @code
+@item *
+@dfn{Multiplication}.
+
+@item /
+@dfn{Division}. Truncation is the same as the C operator @samp{/}
+
+@item %
+@dfn{Remainder}.
+
+@item <
+@itemx <<
+@dfn{Shift Left}. Same as the C operator @samp{<<}
+
+@item >
+@itemx >>
+@dfn{Shift Right}. Same as the C operator @samp{>>}
+@end table
+
+@item
+Intermediate precedence
+
+@table @code
+@item |
+
+@dfn{Bitwise Inclusive Or}.
+
+@item &
+@dfn{Bitwise And}.
+
+@item ^
+@dfn{Bitwise Exclusive Or}.
+
+@item !
+@dfn{Bitwise Or Not}.
+@end table
+
+@item
+Lowest Precedence
+
+@table @code
+@item +
+@cindex addition, permitted arguments
+@cindex plus, permitted arguments
+@cindex arguments for addition
+@dfn{Addition}. If either argument is absolute, the result
+has the section of the other argument.
+If either argument is pass1 or undefined, the result is pass1.
+Otherwise @code{+} is illegal.
+
+@item -
+@cindex subtraction, permitted arguments
+@cindex minus, permitted arguments
+@cindex arguments for subtraction
+@dfn{Subtraction}. If the right argument is absolute, the
+result has the section of the left argument.
+If either argument is pass1 the result is pass1.
+If either argument is undefined the result is difference section.
+If both arguments are in the same section, the result is absolute---provided
+that section is one of text, data or bss.
+Otherwise subtraction is illegal.
+@end table
+@end enumerate
+
+The sense of the rule for addition is that it's only meaningful to add
+the @emph{offsets} in an address; you can only have a defined section in
+one of the two arguments.
+
+Similarly, you can't subtract quantities from two different sections.
+
+@node Pseudo Ops, Machine Dependent, Expressions, Top
+@chapter Assembler Directives
+
+@cindex directives, machine independent
+@cindex pseudo-ops, machine independent
+@cindex machine independent directives
+All assembler directives have names that begin with a period (@samp{.}).
+The rest of the name is letters, usually in lower case.
+
+This chapter discusses directives present regardless of the target
+machine configuration for the GNU assembler.
+
+@menu
+* Abort:: @code{.abort}
+* coff-ABORT:: @code{.ABORT}
+* Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
+* App-File:: @code{.app-file @var{string}}
+* Ascii:: @code{.ascii "@var{string}"}@dots{}
+* Asciz:: @code{.asciz "@var{string}"}@dots{}
+* Byte:: @code{.byte @var{expressions}}
+* Comm:: @code{.comm @var{symbol} , @var{length} }
+* Data:: @code{.data @var{subsection}}
+* Def:: @code{.def @var{name}}
+* Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
+* Dim:: @code{.dim}
+* Double:: @code{.double @var{flonums}}
+* Eject:: @code{.eject}
+* Else:: @code{.else}
+* Endef:: @code{.endef}
+* Endif:: @code{.endif}
+* Equ:: @code{.equ @var{symbol}, @var{expression}}
+* Extern:: @code{.extern}
+* File:: @code{.file @var{string}}
+* Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
+* Float:: @code{.float @var{flonums}}
+* Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
+* hword:: @code{.hword @var{expressions}}
+* Ident:: @code{.ident}
+* If:: @code{.if @var{absolute expression}}
+* Include:: @code{.include "@var{file}"}
+* Int:: @code{.int @var{expressions}}
+* Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
+* Lflags:: @code{.lflags}
+* Line:: @code{.line @var{line-number}}
+* Ln:: @code{.ln @var{line-number}}
+* List:: @code{.list}
+* Long:: @code{.long @var{expressions}}
+* Lsym:: @code{.lsym @var{symbol}, @var{expression}}
+* Nolist:: @code{.nolist}
+* Octa:: @code{.octa @var{bignums}}
+* Org:: @code{.org @var{new-lc} , @var{fill}}
+* Psize:: @code{.psize @var{lines}, @var{columns}}
+* Quad:: @code{.quad @var{bignums}}
+* Sbttl:: @code{.sbttl "@var{subheading}"}
+* Scl:: @code{.scl @var{class}}
+* Section:: @code{.section @var{name}, @var{subsection}}
+* Set:: @code{.set @var{symbol}, @var{expression}}
+* Short:: @code{.short @var{expressions}}
+* Single:: @code{.single @var{flonums}}
+* Size:: @code{.size}
+* Space:: @code{.space @var{size} , @var{fill}}
+* Stab:: @code{.stabd, .stabn, .stabs}
+* Tag:: @code{.tag @var{structname}}
+* Text:: @code{.text @var{subsection}}
+* Title:: @code{.title "@var{heading}"}
+* Type:: @code{.type @var{int}}
+* Val:: @code{.val @var{addr}}
+* Word:: @code{.word @var{expressions}}
+* Deprecated:: Deprecated Directives
+@end menu
+
+@node Abort, coff-ABORT, Pseudo Ops, Pseudo Ops
+@section @code{.abort}
+
+@cindex @code{abort} directive
+@cindex stopping the assembly
+This directive stops the assembly immediately. It is for
+compatibility with other assemblers. The original idea was that the
+assembly language source would be piped into the assembler. If the sender
+of the source quit, it could use this directive tells @code{as} to
+quit also. One day @code{.abort} will not be supported.
+
+@node coff-ABORT, Align, Abort, Pseudo Ops
+@section @code{.ABORT}
+
+@cindex @code{ABORT} directive
+When producing COFF output, @code{as} accepts this directive as a
+synonym for @samp{.abort}.
+
+
+When producing @code{b.out} output, @code{as} accepts this directive,
+but ignores it.
+
+@node Align, App-File, coff-ABORT, Pseudo Ops
+@section @code{.align @var{abs-expr} , @var{abs-expr}}
+
+@cindex padding the location counter
+@cindex advancing location counter
+@cindex location counter, advancing
+@cindex @code{align} directive
+Pad the location counter (in the current subsection) to a particular
+storage boundary. The first expression (which must be absolute) is the
+number of low-order zero bits the location counter will have after
+advancement. For example @samp{.align 3} will advance the location
+counter until it a multiple of 8. If the location counter is already a
+multiple of 8, no change is needed.
+
+The second expression (also absolute) gives the value to be stored in
+the padding bytes. It (and the comma) may be omitted. If it is
+omitted, the padding bytes are zero.
+
+@node App-File, Ascii, Align, Pseudo Ops
+@section @code{.app-file @var{string}}
+
+@cindex logical file name
+@cindex file name, logical
+@cindex @code{app-file} directive
+@code{.app-file}
+tells @code{as} that we are about to start a new
+logical file. @var{string} is the new file name. In general, the
+filename is recognized whether or not it is surrounded by quotes @samp{"};
+but if you wish to specify an empty file name is permitted,
+you must give the quotes--@code{""}. This statement may go away in
+future: it is only recognized to be compatible with old @code{as}
+programs.@refill
+
+@node Ascii, Asciz, App-File, Pseudo Ops
+@section @code{.ascii "@var{string}"}@dots{}
+
+@cindex @code{ascii} directive
+@cindex string literals
+@code{.ascii} expects zero or more string literals (@pxref{Strings})
+separated by commas. It assembles each string (with no automatic
+trailing zero byte) into consecutive addresses.
+
+@node Asciz, Byte, Ascii, Pseudo Ops
+@section @code{.asciz "@var{string}"}@dots{}
+
+@cindex @code{asciz} directive
+@cindex zero-terminated strings
+@cindex null-terminated strings
+@code{.asciz} is just like @code{.ascii}, but each string is followed by
+a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
+
+@node Byte, Comm, Asciz, Pseudo Ops
+@section @code{.byte @var{expressions}}
+
+@cindex @code{byte} directive
+@cindex integers, one byte
+@code{.byte} expects zero or more expressions, separated by commas.
+Each expression is assembled into the next byte.
+
+@node Comm, Data, Byte, Pseudo Ops
+@section @code{.comm @var{symbol} , @var{length} }
+
+@cindex @code{comm} directive
+@cindex symbol, common
+@code{.comm} declares a named common area in the bss section. Normally
+@code{ld} reserves memory addresses for it during linking, so no partial
+program defines the location of the symbol. Use @code{.comm} to tell
+@code{ld} that it must be at least @var{length} bytes long. @code{ld}
+will allocate space for each @code{.comm} symbol that is at least as
+long as the longest @code{.comm} request in any of the partial programs
+linked. @var{length} is an absolute expression.
+
+@node Data, Def, Comm, Pseudo Ops
+@section @code{.data @var{subsection}}
+
+@cindex @code{data} directive
+@code{.data} tells @code{as} to assemble the following statements onto the
+end of the data subsection numbered @var{subsection} (which is an
+absolute expression). If @var{subsection} is omitted, it defaults
+to zero.
+
+@node Def, Desc, Data, Pseudo Ops
+@section @code{.def @var{name}}
+
+@cindex @code{def} directive
+@cindex COFF symbols, debugging
+@cindex debugging COFF symbols
+Begin defining debugging information for a symbol @var{name}; the
+definition extends until the @code{.endef} directive is encountered.
+
+This directive is only observed when @code{as} is configured for COFF
+format output; when producing @code{b.out}, @samp{.def} is recognized,
+but ignored.
+
+@node Desc, Dim, Def, Pseudo Ops
+@section @code{.desc @var{symbol}, @var{abs-expression}}
+
+@cindex @code{desc} directive
+@cindex COFF symbol descriptor
+@cindex symbol descriptor, COFF
+This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
+to the low 16 bits of an absolute expression.
+
+The @samp{.desc} directive is not available when @code{as} is
+configured for COFF output; it is only for @code{a.out} or @code{b.out}
+object format. For the sake of compatibility, @code{as} will accept
+it, but produce no output, when configured for COFF.
+
+@node Dim, Double, Desc, Pseudo Ops
+@section @code{.dim}
+
+@cindex @code{dim} directive
+@cindex COFF auxiliary symbol information
+@cindex auxiliary symbol information, COFF
+This directive is generated by compilers to include auxiliary debugging
+information in the symbol table. It is only permitted inside
+@code{.def}/@code{.endef} pairs.
+
+@samp{.dim} is only meaningful when generating COFF format output; when
+@code{as} is generating @code{b.out}, it accepts this directive but
+ignores it.
+
+@node Double, Eject, Dim, Pseudo Ops
+@section @code{.double @var{flonums}}
+
+@cindex @code{double} directive
+@cindex floating point numbers (double)
+@code{.double} expects zero or more flonums, separated by commas. It
+assembles floating point numbers.
+The exact kind of floating point numbers emitted depends on how
+@code{as} is configured. @xref{Machine Dependent}.
+
+@node Eject, Else, Double, Pseudo Ops
+@section @code{.eject}
+
+@cindex @code{eject} directive
+@cindex new page, in listings
+@cindex page, in listings
+@cindex listing control: new page
+Force a page break at this point, when generating assembly listings.
+
+@node Else, Endef, Eject, Pseudo Ops
+@section @code{.else}
+
+@cindex @code{else} directive
+@code{.else} is part of the @code{as} support for conditional
+assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
+of code to be assembled if the condition for the preceding @code{.if}
+was false.
+
+
+@node Endef, Endif, Else, Pseudo Ops
+@section @code{.endef}
+
+@cindex @code{endef} directive
+This directive flags the end of a symbol definition begun with
+@code{.def}.
+
+@samp{.endef} is only meaningful when generating COFF format output; if
+@code{as} is configured to generate @code{b.out}, it accepts this
+directive but ignores it.
+
+@node Endif, Equ, Endef, Pseudo Ops
+@section @code{.endif}
+
+@cindex @code{endif} directive
+@code{.endif} is part of the @code{as} support for conditional assembly;
+it marks the end of a block of code that is only assembled
+conditionally. @xref{If,,@code{.if}}.
+
+@node Equ, Extern, Endif, Pseudo Ops
+@section @code{.equ @var{symbol}, @var{expression}}
+
+@cindex @code{equ} directive
+@cindex assigning values to symbols
+@cindex symbols, assigning values to
+This directive sets the value of @var{symbol} to @var{expression}.
+It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
+
+@node Extern, File, Equ, Pseudo Ops
+@section @code{.extern}
+
+@cindex @code{extern} directive
+@code{.extern} is accepted in the source program---for compatibility
+with other assemblers---but it is ignored. @code{as} treats
+all undefined symbols as external.
+
+@node File, Fill, Extern, Pseudo Ops
+@section @code{.file @var{string}}
+
+@cindex @code{file} directive
+@cindex logical file name
+@cindex file name, logical
+@code{.file} (which may also be spelled @samp{.app-file}) tells
+@code{as} that we are about to start a new logical file.
+@var{string} is the new file name. In general, the filename is
+recognized whether or not it is surrounded by quotes @samp{"}; but if
+you wish to specify an empty file name, you must give the
+quotes--@code{""}. This statement may go away in future: it is only
+recognized to be compatible with old @code{as} programs.
+In some configurations of @code{as}, @code{.file} has already been
+removed to avoid conflicts with other assemblers. @xref{Machine Dependent}.
+
+@node Fill, Float, File, Pseudo Ops
+@section @code{.fill @var{repeat} , @var{size} , @var{value}}
+
+@cindex @code{fill} directive
+@cindex writing patterns in memory
+@cindex patterns, writing in memory
+@var{result}, @var{size} and @var{value} are absolute expressions.
+This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
+may be zero or more. @var{Size} may be zero or more, but if it is
+more than 8, then it is deemed to have the value 8, compatible with
+other people's assemblers. The contents of each @var{repeat} bytes
+is taken from an 8-byte number. The highest order 4 bytes are
+zero. The lowest order 4 bytes are @var{value} rendered in the
+byte-order of an integer on the computer @code{as} is assembling for.
+Each @var{size} bytes in a repetition is taken from the lowest order
+@var{size} bytes of this number. Again, this bizarre behavior is
+compatible with other people's assemblers.
+
+@var{size} and @var{value} are optional.
+If the second comma and @var{value} are absent, @var{value} is
+assumed zero. If the first comma and following tokens are absent,
+@var{size} is assumed to be 1.
+
+@node Float, Global, Fill, Pseudo Ops
+@section @code{.float @var{flonums}}
+
+@cindex floating point numbers (single)
+@cindex @code{float} directive
+This directive assembles zero or more flonums, separated by commas. It
+has the same effect as @code{.single}.
+The exact kind of floating point numbers emitted depends on how
+@code{as} is configured.
+@xref{Machine Dependent}.
+
+@node Global, hword, Float, Pseudo Ops
+@section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
+
+@cindex @code{global} directive
+@cindex symbol, making visible to linker
+@code{.global} makes the symbol visible to @code{ld}. If you define
+@var{symbol} in your partial program, its value is made available to
+other partial programs that are linked with it. Otherwise,
+@var{symbol} will take its attributes from a symbol of the same name
+from another partial program it is linked with.
+
+Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
+compatibility with other assemblers.
+
+@node hword, Ident, Global, Pseudo Ops
+@section @code{.hword @var{expressions}}
+
+@cindex @code{hword} directive
+@cindex integers, 16-bit
+@cindex numbers, 16-bit
+@cindex sixteen bit integers
+This expects zero or more @var{expressions}, and emits
+a 16 bit number for each.
+
+This directive is a synonym for @samp{.short}; depending on the target
+architecture, it may also be a synonym for @samp{.word}.
+
+@node Ident, If, hword, Pseudo Ops
+@section @code{.ident}
+
+@cindex @code{ident} directive
+This directive is used by some assemblers to place tags in object files.
+@code{as} simply accepts the directive for source-file
+compatibility with such assemblers, but does not actually emit anything
+for it.
+
+@node If, Include, Ident, Pseudo Ops
+@section @code{.if @var{absolute expression}}
+
+@cindex conditional assembly
+@cindex @code{if} directive
+@code{.if} marks the beginning of a section of code which is only
+considered part of the source program being assembled if the argument
+(which must be an @var{absolute expression}) is non-zero. The end of
+the conditional section of code must be marked by @code{.endif}
+(@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
+alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}.
+
+The following variants of @code{.if} are also supported:
+@table @code
+@item .ifdef @var{symbol}
+@cindex @code{ifdef} directive
+Assembles the following section of code if the specified @var{symbol}
+has been defined.
+
+
+@item .ifndef @var{symbol}
+@itemx ifnotdef @var{symbol}
+@cindex @code{ifndef} directive
+@cindex @code{ifnotdef} directive
+Assembles the following section of code if the specified @var{symbol}
+has not been defined. Both spelling variants are equivalent.
+
+@end table
+
+@node Include, Int, If, Pseudo Ops
+@section @code{.include "@var{file}"}
+
+@cindex @code{include} directive
+@cindex supporting files, including
+@cindex files, including
+This directive provides a way to include supporting files at specified
+points in your source program. The code from @var{file} is assembled as
+if it followed the point of the @code{.include}; when the end of the
+included file is reached, assembly of the original file continues. You
+can control the search paths used with the @samp{-I} command-line option
+(@pxref{Invoking,,Command-Line Options}). Quotation marks are required
+around @var{file}.
+
+@node Int, Lcomm, Include, Pseudo Ops
+@section @code{.int @var{expressions}}
+
+@cindex @code{int} directive
+@cindex integers, 32-bit
+Expect zero or more @var{expressions}, of any section, separated by
+commas. For each expression, emit a
+32-bit
+number that will, at run
+time, be the value of that expression. The byte order of the
+expression depends on what kind of computer will run the program.
+
+@node Lcomm, Lflags, Int, Pseudo Ops
+@section @code{.lcomm @var{symbol} , @var{length}}
+
+@cindex @code{lcomm} directive
+@cindex local common symbols
+@cindex symbols, local common
+Reserve @var{length} (an absolute expression) bytes for a local common
+denoted by @var{symbol}. The section and value of @var{symbol} are
+those of the new local common. The addresses are allocated in the bss
+section, so at run-time the bytes will start off zeroed. @var{Symbol}
+is not declared global (@pxref{Global,,@code{.global}}), so is normally
+not visible to @code{ld}.
+
+@node Lflags, Line, Lcomm, Pseudo Ops
+@section @code{.lflags}
+
+@cindex @code{lflags} directive (ignored)
+@code{as} accepts this directive, for compatibility with other
+assemblers, but ignores it.
+
+@node Line, Ln, Lflags, Pseudo Ops
+@section @code{.line @var{line-number}}
+
+@cindex @code{line} directive
+@cindex logical line number
+Tell @code{as} to change the logical line number. @var{line-number} must be
+an absolute expression. The next line will have that logical line
+number. So any other statements on the current line (after a statement
+separator
+character)
+will be reported as on logical line number
+@var{line-number} @minus{} 1.
+One day this directive will be unsupported: it is used only
+for compatibility with existing assembler programs. @refill
+
+@emph{Warning:} In the AMD29K configuration of as, this command is
+only available with the name @code{.ln}, rather than as either
+@code{.line} or @code{.ln}.
+
+Even though this is a directive associated with the @code{a.out} or
+@code{b.out} object-code formats, @code{as} will still recognize it
+when producing COFF output, and will treat @samp{.line} as though it
+were the COFF @samp{.ln} @emph{if} it is found outside a
+@code{.def}/@code{.endef} pair.
+
+Inside a @code{.def}, @samp{.line} is, instead, one of the directives
+used by compilers to generate auxiliary symbol information for
+debugging.
+
+@node Ln, List, Line, Pseudo Ops
+@section @code{.ln @var{line-number}}
+
+@cindex @code{ln} directive
+@samp{.ln} is a synonym for @samp{.line}.
+
+@node List, Long, Ln, Pseudo Ops
+@section @code{.list}
+
+@cindex @code{list} directive
+@cindex listing control, turning on
+Control (in conjunction with the @code{.nolist} directive) whether or
+not assembly listings are generated. These two directives maintain an
+internal counter (which is zero initially). @code{.list} increments the
+counter, and @code{.nolist} decrements it. Assembly listings are
+generated whenever the counter is greater than zero.
+
+By default, listings are disabled. When you enable them (with the
+@samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
+the initial value of the listing counter is one.
+
+@node Long, Lsym, List, Pseudo Ops
+@section @code{.long @var{expressions}}
+
+@cindex @code{long} directive
+@code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
+
+@node Lsym, Nolist, Long, Pseudo Ops
+@section @code{.lsym @var{symbol}, @var{expression}}
+
+@cindex @code{lsym} directive
+@cindex symbol, not referenced in assembly
+@code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
+the hash table, ensuring it cannot be referenced by name during the
+rest of the assembly. This sets the attributes of the symbol to be
+the same as the expression value:
+@smallexample
+@var{other} = @var{descriptor} = 0
+@var{type} = @r{(section of @var{expression})}
+@var{value} = @var{expression}
+@end smallexample
+@noindent
+The new symbol is not flagged as external.
+
+@node Nolist, Octa, Lsym, Pseudo Ops
+@section @code{.nolist}
+
+@cindex @code{nolist} directive
+@cindex listing control, turning off
+Control (in conjunction with the @code{.list} directive) whether or
+not assembly listings are generated. These two directives maintain an
+internal counter (which is zero initially). @code{.list} increments the
+counter, and @code{.nolist} decrements it. Assembly listings are
+generated whenever the counter is greater than zero.
+
+@node Octa, Org, Nolist, Pseudo Ops
+@section @code{.octa @var{bignums}}
+
+@c FIXME: double size emitted for "octa" on i960, others? Or warn?
+@cindex @code{octa} directive
+@cindex integer, 16-byte
+@cindex sixteen byte integer
+This directive expects zero or more bignums, separated by commas. For each
+bignum, it emits a 16-byte integer.
+
+The term ``octa'' comes from contexts in which a ``word'' is two bytes;
+hence @emph{octa}-word for 16 bytes.
+
+@node Org, Psize, Octa, Pseudo Ops
+@section @code{.org @var{new-lc} , @var{fill}}
+
+@cindex @code{org} directive
+@cindex location counter, advancing
+@cindex advancing location counter
+@cindex current address, advancing
+@code{.org} will advance the location counter of the current section to
+@var{new-lc}. @var{new-lc} is either an absolute expression or an
+expression with the same section as the current subsection. That is,
+you can't use @code{.org} to cross sections: if @var{new-lc} has the
+wrong section, the @code{.org} directive is ignored. To be compatible
+with former assemblers, if the section of @var{new-lc} is absolute,
+@code{as} will issue a warning, then pretend the section of @var{new-lc}
+is the same as the current subsection.
+
+@code{.org} may only increase the location counter, or leave it
+unchanged; you cannot use @code{.org} to move the location counter
+backwards.
+
+@c double negative used below "not undefined" because this is a specific
+@c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
+@c section. pesch@cygnus.com 18feb91
+Because @code{as} tries to assemble programs in one pass @var{new-lc}
+may not be undefined. If you really detest this restriction we eagerly await
+a chance to share your improved assembler.
+
+Beware that the origin is relative to the start of the section, not
+to the start of the subsection. This is compatible with other
+people's assemblers.
+
+When the location counter (of the current subsection) is advanced, the
+intervening bytes are filled with @var{fill} which should be an
+absolute expression. If the comma and @var{fill} are omitted,
+@var{fill} defaults to zero.
+
+@node Psize, Quad, Org, Pseudo Ops
+@section @code{.psize @var{lines} , @var{columns}}
+
+@cindex @code{psize} directive
+@cindex listing control: paper size
+@cindex paper size, for listings
+Use this directive to declare the number of lines---and, optionally, the
+number of columns---to use for each page, when generating listings.
+
+If you don't use @code{.psize}, listings will use a default line-count
+of 60. You may omit the comma and @var{columns} specification; the
+default width is 200 columns.
+
+@code{as} will generate formfeeds whenever the specified number of
+lines is exceeded (or whenever you explicitly request one, using
+@code{.eject}).
+
+If you specify @var{lines} as @code{0}, no formfeeds are generated save
+those explicitly specified with @code{.eject}.
+
+@node Quad, Sbttl, Psize, Pseudo Ops
+@section @code{.quad @var{bignums}}
+
+@cindex @code{quad} directive
+@code{.quad} expects zero or more bignums, separated by commas. For
+each bignum, it emits
+an 8-byte integer. If the bignum won't fit in 8
+bytes, it prints a warning message; and just takes the lowest order 8
+bytes of the bignum.@refill
+@cindex eight-byte integer
+@cindex integer, 8-byte
+
+The term ``quad'' comes from contexts in which a ``word'' is two bytes;
+hence @emph{quad}-word for 8 bytes.
+
+@node Sbttl, Scl, Quad, Pseudo Ops
+@section @code{.sbttl "@var{subheading}"}
+
+@cindex @code{sbttl} directive
+@cindex subtitles for listings
+@cindex listing control: subtitle
+Use @var{subheading} as the title (third line, immediately after the
+title line) when generating assembly listings.
+
+This directive affects subsequent pages, as well as the current page if
+it appears within ten lines of the top of a page.
+
+@node Scl, Section, Sbttl, Pseudo Ops
+@section @code{.scl @var{class}}
+
+@cindex @code{scl} directive
+@cindex symbol storage class (COFF)
+@cindex COFF symbol storage class
+Set the storage-class value for a symbol. This directive may only be
+used inside a @code{.def}/@code{.endef} pair. Storage class may flag
+whether a symbol is static or external, or it may record further
+symbolic debugging information.
+
+The @samp{.scl} directive is primarily associated with COFF output; when
+configured to generate @code{b.out} output format, @code{as} will
+accept this directive but ignore it.
+
+@node Section, Set, Scl, Pseudo Ops
+@section @code{.section @var{name}, @var{subsection}}
+
+@cindex @code{section} directive
+@cindex named section (COFF)
+@cindex COFF named section
+Assemble the following code into end of subsection numbered
+@var{subsection} in the COFF named section @var{name}. If you omit
+@var{subsection}, @code{as} uses subsection number zero.
+@samp{.section .text} is equivalent to the @code{.text} directive;
+@samp{.section .data} is equivalent to the @code{.data} directive.
+
+@node Set, Short, Section, Pseudo Ops
+@section @code{.set @var{symbol}, @var{expression}}
+
+@cindex @code{set} directive
+@cindex symbol value, setting
+This directive sets the value of @var{symbol} to @var{expression}. This
+will change @var{symbol}'s value and type to conform to
+@var{expression}. If @var{symbol} was flagged as external, it remains
+flagged. (@xref{Symbol Attributes}.)
+
+You may @code{.set} a symbol many times in the same assembly.
+If the expression's section is unknowable during pass 1, a second
+pass over the source program will be forced. The second pass is
+currently not implemented. @code{as} will abort with an error
+message if one is required.
+
+If you @code{.set} a global symbol, the value stored in the object
+file is the last value stored into it.
+
+@node Short, Single, Set, Pseudo Ops
+@section @code{.short @var{expressions}}
+
+@cindex @code{short} directive
+@code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
+@node Single, Size, Short, Pseudo Ops
+@section @code{.single @var{flonums}}
+
+@cindex @code{single} directive
+@cindex floating point numbers (single)
+This directive assembles zero or more flonums, separated by commas. It
+has the same effect as @code{.float}.
+The exact kind of floating point numbers emitted depends on how
+@code{as} is configured. @xref{Machine Dependent}.
+
+@node Size, Space, Single, Pseudo Ops
+@section @code{.size}
+
+@cindex @code{size} directive
+This directive is generated by compilers to include auxiliary debugging
+information in the symbol table. It is only permitted inside
+@code{.def}/@code{.endef} pairs.
+
+@samp{.size} is only meaningful when generating COFF format output; when
+@code{as} is generating @code{b.out}, it accepts this directive but
+ignores it.
+
+@node Space, Stab, Size, Pseudo Ops
+@section @code{.space @var{size} , @var{fill}}
+
+@cindex @code{space} directive
+@cindex filling memory
+This directive emits @var{size} bytes, each of value @var{fill}. Both
+@var{size} and @var{fill} are absolute expressions. If the comma
+and @var{fill} are omitted, @var{fill} is assumed to be zero.
+
+@section @code{.space}
+
+@cindex @code{space} directive
+On the AMD 29K, this directive is ignored; it is accepted for
+compatibility with other AMD 29K assemblers.
+
+@quotation
+@emph{Warning:} In other versions of the GNU assembler, the directive
+@code{.space} has the effect of @code{.block} @xref{Machine Dependent}.
+@end quotation
+
+@node Stab, Tag, Space, Pseudo Ops
+@section @code{.stabd, .stabn, .stabs}
+
+@cindex symbolic debuggers, information for
+@cindex @code{stab@var{x}} directives
+There are three directives that begin @samp{.stab}.
+All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
+The symbols are not entered in the @code{as} hash table: they
+cannot be referenced elsewhere in the source file.
+Up to five fields are required:
+@table @var
+@item string
+This is the symbol's name. It may contain any character except @samp{\000},
+so is more general than ordinary symbol names. Some debuggers used to
+code arbitrarily complex structures into symbol names using this field.
+@item type
+An absolute expression. The symbol's type is set to the low 8
+bits of this expression.
+Any bit pattern is permitted, but @code{ld} and debuggers will choke on
+silly bit patterns.
+@item other
+An absolute expression.
+The symbol's ``other'' attribute is set to the low 8 bits of this expression.
+@item desc
+An absolute expression.
+The symbol's descriptor is set to the low 16 bits of this expression.
+@item value
+An absolute expression which becomes the symbol's value.
+@end table
+
+If a warning is detected while reading a @code{.stabd}, @code{.stabn},
+or @code{.stabs} statement, the symbol has probably already been created
+and you will get a half-formed symbol in your object file. This is
+compatible with earlier assemblers!
+
+@table @code
+@cindex @code{stabd} directive
+@item .stabd @var{type} , @var{other} , @var{desc}
+
+The ``name'' of the symbol generated is not even an empty string.
+It is a null pointer, for compatibility. Older assemblers used a
+null pointer so they didn't waste space in object files with empty
+strings.
+
+The symbol's value is set to the location counter,
+relocatably. When your program is linked, the value of this symbol
+will be where the location counter was when the @code{.stabd} was
+assembled.
+
+@item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
+@cindex @code{stabn} directive
+The name of the symbol is set to the empty string @code{""}.
+
+@item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
+@cindex @code{stabs} directive
+All five fields are specified.
+@end table
+
+@node Tag, Text, Stab, Pseudo Ops
+@section @code{.tag @var{structname}}
+
+@cindex COFF structure debugging
+@cindex structure debugging, COFF
+@cindex @code{tag} directive
+This directive is generated by compilers to include auxiliary debugging
+information in the symbol table. It is only permitted inside
+@code{.def}/@code{.endef} pairs. Tags are used to link structure
+definitions in the symbol table with instances of those structures.
+
+@samp{.tag} is only used when generating COFF format output; when
+@code{as} is generating @code{b.out}, it accepts this directive but
+ignores it.
+
+@node Text, Title, Tag, Pseudo Ops
+@section @code{.text @var{subsection}}
+
+@cindex @code{text} directive
+Tells @code{as} to assemble the following statements onto the end of
+the text subsection numbered @var{subsection}, which is an absolute
+expression. If @var{subsection} is omitted, subsection number zero
+is used.
+
+@node Title, Type, Text, Pseudo Ops
+@section @code{.title "@var{heading}"}
+
+@cindex @code{title} directive
+@cindex listing control: title line
+Use @var{heading} as the title (second line, immediately after the
+source file name and pagenumber) when generating assembly listings.
+
+This directive affects subsequent pages, as well as the current page if
+it appears within ten lines of the top of a page.
+
+@node Type, Val, Title, Pseudo Ops
+@section @code{.type @var{int}}
+
+@cindex COFF symbol type
+@cindex symbol type, COFF
+@cindex @code{type} directive
+This directive, permitted only within @code{.def}/@code{.endef} pairs,
+records the integer @var{int} as the type attribute of a symbol table entry.
+
+@samp{.type} is associated only with COFF format output; when
+@code{as} is configured for @code{b.out} output, it accepts this
+directive but ignores it.
+
+@node Val, Word, Type, Pseudo Ops
+@section @code{.val @var{addr}}
+
+@cindex @code{val} directive
+@cindex COFF value attribute
+@cindex value attribute, COFF
+This directive, permitted only within @code{.def}/@code{.endef} pairs,
+records the address @var{addr} as the value attribute of a symbol table
+entry.
+
+@samp{.val} is used only for COFF output; when @code{as} is
+configured for @code{b.out}, it accepts this directive but ignores it.
+
+@node Word, Deprecated, Val, Pseudo Ops
+@section @code{.word @var{expressions}}
+
+@cindex @code{word} directive
+This directive expects zero or more @var{expressions}, of any section,
+separated by commas.
+
+The size of the number emitted, and its byte order,
+depends on what kind of computer will run the program.
+
+@c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
+@c happen---32-bit addressability, period; no long/short jumps.
+@cindex difference tables altered
+@cindex altered difference tables
+@quotation
+@emph{Warning: Special Treatment to support Compilers}
+@end quotation
+
+Machines with a 32-bit address space, but that do less than 32-bit
+addressing, require the following special treatment. If the machine of
+interest to you does 32-bit addressing (or doesn't require it;
+@pxref{Machine Dependent}), you can ignore this issue.
+
+In order to assemble compiler output into something that will work,
+@code{as} will occasionlly do strange things to @samp{.word} directives.
+Directives of the form @samp{.word sym1-sym2} are often emitted by
+compilers as part of jump tables. Therefore, when @code{as} assembles a
+directive of the form @samp{.word sym1-sym2}, and the difference between
+@code{sym1} and @code{sym2} does not fit in 16 bits, @code{as} will
+create a @dfn{secondary jump table}, immediately before the next label.
+This secondary jump table will be preceded by a short-jump to the
+first byte after the secondary table. This short-jump prevents the flow
+of control from accidentally falling into the new table. Inside the
+table will be a long-jump to @code{sym2}. The original @samp{.word}
+will contain @code{sym1} minus the address of the long-jump to
+@code{sym2}.
+
+If there were several occurrences of @samp{.word sym1-sym2} before the
+secondary jump table, all of them will be adjusted. If there was a
+@samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
+long-jump to @code{sym4} will be included in the secondary jump table,
+and the @code{.word} directives will be adjusted to contain @code{sym3}
+minus the address of the long-jump to @code{sym4}; and so on, for as many
+entries in the original jump table as necessary.
+
+
+@node Deprecated, , Word, Pseudo Ops
+@section Deprecated Directives
+
+@cindex deprecated directives
+@cindex obsolescent directives
+One day these directives won't work.
+They are included for compatibility with older assemblers.
+@table @t
+@item .abort
+@item .app-file
+@item .line
+@end table
+
+@node Machine Dependent, Copying, Pseudo Ops, Top
+@chapter Machine Dependent Features
+
+@cindex machine dependencies
+The machine instruction sets are (almost by definition) different on
+each machine where @code{as} runs. Floating point representations
+vary as well, and @code{as} often supports a few additional
+directives or command-line options for compatibility with other
+assemblers on a particular platform. Finally, some versions of
+@code{as} support special pseudo-instructions for branch
+optimization.
+
+This chapter discusses most of these differences, though it does not
+include details on any machine's instruction set. For details on that
+subject, see the hardware manufacturer's manual.
+
+@menu
+* Vax-Dependent:: VAX Dependent Features
+* AMD29K-Dependent:: AMD 29K Dependent Features
+* H8/300-Dependent:: AMD 29K Dependent Features
+* i960-Dependent:: Intel 80960 Dependent Features
+* M68K-Dependent:: M680x0 Dependent Features
+* Sparc-Dependent:: SPARC Dependent Features
+* i386-Dependent:: 80386 Dependent Features
+@end menu
+
+@node Vax-Dependent, AMD29K-Dependent, Machine Dependent, Machine Dependent
+@section VAX Dependent Features
+
+@cindex VAX support
+@menu
+* Vax-Opts:: VAX Command-Line Options
+* VAX-float:: VAX Floating Point
+* VAX-directives:: Vax Machine Directives
+* VAX-opcodes:: VAX Opcodes
+* VAX-branch:: VAX Branch Improvement
+* VAX-operands:: VAX Operands
+* VAX-no:: Not Supported on VAX
+@end menu
+
+@node Vax-Opts, VAX-float, Vax-Dependent, Vax-Dependent
+@subsection VAX Command-Line Options
+
+@cindex command-line options ignored, VAX
+@cindex VAX command-line options ignored
+The Vax version of @code{as} accepts any of the following options,
+gives a warning message that the option was ignored and proceeds.
+These options are for compatibility with scripts designed for other
+people's assemblers.
+
+@table @asis
+@item @kbd{-D} (Debug)
+@itemx @kbd{-S} (Symbol Table)
+@itemx @kbd{-T} (Token Trace)
+@cindex @code{-D}, ignored on VAX
+@cindex @code{-S}, ignored on VAX
+@cindex @code{-T}, ignored on VAX
+These are obsolete options used to debug old assemblers.
+
+@item @kbd{-d} (Displacement size for JUMPs)
+@cindex @code{-d}, VAX option
+This option expects a number following the @kbd{-d}. Like options
+that expect filenames, the number may immediately follow the
+@kbd{-d} (old standard) or constitute the whole of the command line
+argument that follows @kbd{-d} (GNU standard).
+
+@item @kbd{-V} (Virtualize Interpass Temporary File)
+@cindex @code{-V}, redundant on VAX
+Some other assemblers use a temporary file. This option
+commanded them to keep the information in active memory rather
+than in a disk file. @code{as} always does this, so this
+option is redundant.
+
+@item @kbd{-J} (JUMPify Longer Branches)
+@cindex @code{-J}, ignored on VAX
+Many 32-bit computers permit a variety of branch instructions
+to do the same job. Some of these instructions are short (and
+fast) but have a limited range; others are long (and slow) but
+can branch anywhere in virtual memory. Often there are 3
+flavors of branch: short, medium and long. Some other
+assemblers would emit short and medium branches, unless told by
+this option to emit short and long branches.
+
+@item @kbd{-t} (Temporary File Directory)
+@cindex @code{-t}, ignored on VAX
+Some other assemblers may use a temporary file, and this option
+takes a filename being the directory to site the temporary
+file. @code{as} does not use a temporary disk file, so this
+option makes no difference. @kbd{-t} needs exactly one
+filename.
+@end table
+
+@cindex VMS (VAX) options
+@cindex options for VAX/VMS
+@cindex VAX/VMS options
+@cindex @code{-h} option, VAX/VMS
+@cindex @code{-+} option, VAX/VMS
+@cindex Vax-11 C compatibility
+@cindex symbols with lowercase, VAX/VMS
+@c FIXME! look into "I think" below, correct if needed, delete.
+The Vax version of the assembler accepts two options when
+compiled for VMS. They are @kbd{-h}, and @kbd{-+}. The
+@kbd{-h} option prevents @code{as} from modifying the
+symbol-table entries for symbols that contain lowercase
+characters (I think). The @kbd{-+} option causes @code{as} to
+print warning messages if the FILENAME part of the object file,
+or any symbol name is larger than 31 characters. The @kbd{-+}
+option also insertes some code following the @samp{_main}
+symbol so that the object file will be compatible with Vax-11
+"C".
+
+@node VAX-float, VAX-directives, Vax-Opts, Vax-Dependent
+@subsection VAX Floating Point
+
+@cindex VAX floating point
+@cindex floating point, VAX
+Conversion of flonums to floating point is correct, and
+compatible with previous assemblers. Rounding is
+towards zero if the remainder is exactly half the least significant bit.
+
+@code{D}, @code{F}, @code{G} and @code{H} floating point formats
+are understood.
+
+Immediate floating literals (@emph{e.g.} @samp{S`$6.9})
+are rendered correctly. Again, rounding is towards zero in the
+boundary case.
+
+@cindex @code{float} directive, VAX
+@cindex @code{double} directive, VAX
+The @code{.float} directive produces @code{f} format numbers.
+The @code{.double} directive produces @code{d} format numbers.
+
+@node VAX-directives, VAX-opcodes, VAX-float, Vax-Dependent
+@subsection Vax Machine Directives
+
+@cindex machine directives, VAX
+@cindex VAX machine directives
+The Vax version of the assembler supports four directives for
+generating Vax floating point constants. They are described in the
+table below.
+
+@cindex wide floating point directives, VAX
+@table @code
+@item .dfloat
+@cindex @code{dfloat} directive, VAX
+This expects zero or more flonums, separated by commas, and
+assembles Vax @code{d} format 64-bit floating point constants.
+
+@item .ffloat
+@cindex @code{ffloat} directive, VAX
+This expects zero or more flonums, separated by commas, and
+assembles Vax @code{f} format 32-bit floating point constants.
+
+@item .gfloat
+@cindex @code{gfloat} directive, VAX
+This expects zero or more flonums, separated by commas, and
+assembles Vax @code{g} format 64-bit floating point constants.
+
+@item .hfloat
+@cindex @code{hfloat} directive, VAX
+This expects zero or more flonums, separated by commas, and
+assembles Vax @code{h} format 128-bit floating point constants.
+
+@end table
+
+@node VAX-opcodes, VAX-branch, VAX-directives, Vax-Dependent
+@subsection VAX Opcodes
+
+@cindex VAX opcode mnemonics
+@cindex opcode mnemonics, VAX
+@cindex mnemonics for opcodes, VAX
+All DEC mnemonics are supported. Beware that @code{case@dots{}}
+instructions have exactly 3 operands. The dispatch table that
+follows the @code{case@dots{}} instruction should be made with
+@code{.word} statements. This is compatible with all unix
+assemblers we know of.
+
+@node VAX-branch, VAX-operands, VAX-opcodes, Vax-Dependent
+@subsection VAX Branch Improvement
+
+@cindex VAX branch improvement
+@cindex branch improvement, VAX
+@cindex pseudo-ops for branch, VAX
+Certain pseudo opcodes are permitted. They are for branch
+instructions. They expand to the shortest branch instruction that
+will reach the target. Generally these mnemonics are made by
+substituting @samp{j} for @samp{b} at the start of a DEC mnemonic.
+This feature is included both for compatibility and to help
+compilers. If you don't need this feature, don't use these
+opcodes. Here are the mnemonics, and the code they can expand into.
+
+@table @code
+@item jbsb
+@samp{Jsb} is already an instruction mnemonic, so we chose @samp{jbsb}.
+@table @asis
+@item (byte displacement)
+@kbd{bsbb @dots{}}
+@item (word displacement)
+@kbd{bsbw @dots{}}
+@item (long displacement)
+@kbd{jsb @dots{}}
+@end table
+@item jbr
+@itemx jr
+Unconditional branch.
+@table @asis
+@item (byte displacement)
+@kbd{brb @dots{}}
+@item (word displacement)
+@kbd{brw @dots{}}
+@item (long displacement)
+@kbd{jmp @dots{}}
+@end table
+@item j@var{COND}
+@var{COND} may be any one of the conditional branches
+@code{neq nequ eql eqlu gtr geq lss gtru lequ vc vs gequ cc lssu cs}.
+@var{COND} may also be one of the bit tests
+@code{bs bc bss bcs bsc bcc bssi bcci lbs lbc}.
+@var{NOTCOND} is the opposite condition to @var{COND}.
+@table @asis
+@item (byte displacement)
+@kbd{b@var{COND} @dots{}}
+@item (word displacement)
+@kbd{b@var{NOTCOND} foo ; brw @dots{} ; foo:}
+@item (long displacement)
+@kbd{b@var{NOTCOND} foo ; jmp @dots{} ; foo:}
+@end table
+@item jacb@var{X}
+@var{X} may be one of @code{b d f g h l w}.
+@table @asis
+@item (word displacement)
+@kbd{@var{OPCODE} @dots{}}
+@item (long displacement)
+@example
+@var{OPCODE} @dots{}, foo ;
+brb bar ;
+foo: jmp @dots{} ;
+bar:
+@end example
+@end table
+@item jaob@var{YYY}
+@var{YYY} may be one of @code{lss leq}.
+@item jsob@var{ZZZ}
+@var{ZZZ} may be one of @code{geq gtr}.
+@table @asis
+@item (byte displacement)
+@kbd{@var{OPCODE} @dots{}}
+@item (word displacement)
+@example
+@var{OPCODE} @dots{}, foo ;
+brb bar ;
+foo: brw @var{destination} ;
+bar:
+@end example
+@item (long displacement)
+@example
+@var{OPCODE} @dots{}, foo ;
+brb bar ;
+foo: jmp @var{destination} ;
+bar:
+@end example
+@end table
+@item aobleq
+@itemx aoblss
+@itemx sobgeq
+@itemx sobgtr
+@table @asis
+@item (byte displacement)
+@kbd{@var{OPCODE} @dots{}}
+@item (word displacement)
+@example
+@var{OPCODE} @dots{}, foo ;
+brb bar ;
+foo: brw @var{destination} ;
+bar:
+@end example
+@item (long displacement)
+@example
+@var{OPCODE} @dots{}, foo ;
+brb bar ;
+foo: jmp @var{destination} ;
+bar:
+@end example
+@end table
+@end table
+
+@node VAX-operands, VAX-no, VAX-branch, Vax-Dependent
+@subsection VAX Operands
+
+@cindex VAX operand notation
+@cindex operand notation, VAX
+@cindex immediate character, VAX
+@cindex VAX immediate character
+The immediate character is @samp{$} for Unix compatibility, not
+@samp{#} as DEC writes it.
+
+@cindex indirect character, VAX
+@cindex VAX indirect character
+The indirect character is @samp{*} for Unix compatibility, not
+@samp{@@} as DEC writes it.
+
+@cindex displacement sizing character, VAX
+@cindex VAX displacement sizing character
+The displacement sizing character is @samp{`} (an accent grave) for
+Unix compatibility, not @samp{^} as DEC writes it. The letter
+preceding @samp{`} may have either case. @samp{G} is not
+understood, but all other letters (@code{b i l s w}) are understood.
+
+@cindex register names, VAX
+@cindex VAX register names
+Register names understood are @code{r0 r1 r2 @dots{} r15 ap fp sp
+pc}. Any case of letters will do.
+
+For instance
+@smallexample
+tstb *w`$4(r5)
+@end smallexample
+
+Any expression is permitted in an operand. Operands are comma
+separated.
+
+@c There is some bug to do with recognizing expressions
+@c in operands, but I forget what it is. It is
+@c a syntax clash because () is used as an address mode
+@c and to encapsulate sub-expressions.
+
+@node VAX-no, , VAX-operands, Vax-Dependent
+@subsection Not Supported on VAX
+
+@cindex VAX bitfields not supported
+@cindex bitfields, not supported on VAX
+Vax bit fields can not be assembled with @code{as}. Someone
+can add the required code if they really need it.
+
+@node AMD29K-Dependent, H8/300-Dependent, Vax-Dependent, Machine Dependent
+@section AMD 29K Dependent Features
+
+@cindex AMD 29K support
+@cindex 29K support
+@menu
+* AMD29K Options:: Options
+* AMD29K Syntax:: Syntax
+* AMD29K Floating Point:: Floating Point
+* AMD29K Directives:: AMD 29K Machine Directives
+* AMD29K Opcodes:: Opcodes
+@end menu
+
+@node AMD29K Options, AMD29K Syntax, AMD29K-Dependent, AMD29K-Dependent
+@subsection Options
+@cindex AMD 29K options (none)
+@cindex options for AMD29K (none)
+@code{as} has no additional command-line options for the AMD
+29K family.
+
+@node AMD29K Syntax, AMD29K Floating Point, AMD29K Options, AMD29K-Dependent
+@subsection Syntax
+@menu
+* AMD29K-Chars:: Special Characters
+* AMD29K-Regs:: Register Names
+@end menu
+
+@node AMD29K-Chars, AMD29K-Regs, AMD29K Syntax, AMD29K Syntax
+@subsubsection Special Characters
+
+@cindex line comment character, AMD 29K
+@cindex AMD 29K line comment character
+@samp{;} is the line comment character.
+
+@cindex line separator, AMD 29K
+@cindex AMD 29K line separator
+@cindex statement separator, AMD 29K
+@cindex AMD 29K statement separator
+@samp{@@} can be used instead of a newline to separate statements.
+
+@cindex identifiers, AMD 29K
+@cindex AMD 29K identifiers
+The character @samp{?} is permitted in identifiers (but may not begin
+an identifier).
+
+@node AMD29K-Regs, , AMD29K-Chars, AMD29K Syntax
+@subsubsection Register Names
+
+@cindex AMD 29K register names
+@cindex register names, AMD 29K
+General-purpose registers are represented by predefined symbols of the
+form @samp{GR@var{nnn}} (for global registers) or @samp{LR@var{nnn}}
+(for local registers), where @var{nnn} represents a number between
+@code{0} and @code{127}, written with no leading zeros. The leading
+letters may be in either upper or lower case; for example, @samp{gr13}
+and @samp{LR7} are both valid register names.
+
+You may also refer to general-purpose registers by specifying the
+register number as the result of an expression (prefixed with @samp{%%}
+to flag the expression as a register number):
+@smallexample
+%%@var{expression}
+@end smallexample
+@noindent
+---where @var{expression} must be an absolute expression evaluating to a
+number between @code{0} and @code{255}. The range [0, 127] refers to
+global registers, and the range [128, 255] to local registers.
+
+@cindex special purpose registers, AMD 29K
+@cindex AMD 29K special purpose registers
+@cindex protected registers, AMD 29K
+@cindex AMD 29K protected registers
+In addition, @code{as} understands the following protected
+special-purpose register names for the AMD 29K family:
+
+@smallexample
+ vab chd pc0
+ ops chc pc1
+ cps rbp pc2
+ cfg tmc mmu
+ cha tmr lru
+@end smallexample
+
+These unprotected special-purpose register names are also recognized:
+@smallexample
+ ipc alu fpe
+ ipa bp inte
+ ipb fc fps
+ q cr exop
+@end smallexample
+
+@node AMD29K Floating Point, AMD29K Directives, AMD29K Syntax, AMD29K-Dependent
+@subsection Floating Point
+
+@cindex floating point, AMD 29K (@sc{ieee})
+@cindex AMD 29K floating point (@sc{ieee})
+The AMD 29K family uses @sc{ieee} floating-point numbers.
+
+@node AMD29K Directives, AMD29K Opcodes, AMD29K Floating Point, AMD29K-Dependent
+@subsection AMD 29K Machine Directives
+
+@cindex machine directives, AMD 29K
+@cindex AMD 29K machine directives
+@table @code
+@item .block @var{size} , @var{fill}
+@cindex @code{block} directive, AMD 29K
+This directive emits @var{size} bytes, each of value @var{fill}. Both
+@var{size} and @var{fill} are absolute expressions. If the comma
+and @var{fill} are omitted, @var{fill} is assumed to be zero.
+
+In other versions of the GNU assembler, this directive is called
+@samp{.space}.
+@end table
+
+@table @code
+@item .cputype
+@cindex @code{cputype} directive, AMD 29K
+This directive is ignored; it is accepted for compatibility with other
+AMD 29K assemblers.
+
+@item .file
+@cindex @code{file} directive, AMD 29K
+This directive is ignored; it is accepted for compatibility with other
+AMD 29K assemblers.
+
+@quotation
+@emph{Warning:} in other versions of the GNU assembler, @code{.file} is
+used for the directive called @code{.app-file} in the AMD 29K support.
+@end quotation
+
+@item .line
+@cindex @code{line} directive, AMD 29K
+This directive is ignored; it is accepted for compatibility with other
+AMD 29K assemblers.
+
+@item .reg @var{symbol}, @var{expression}
+@cindex @code{reg} directive, AMD 29K
+@code{.reg} has the same effect as @code{.lsym}; @pxref{Lsym,,@code{.lsym}}.
+
+@item .sect
+@cindex @code{sect} directive, AMD 29K
+This directive is ignored; it is accepted for compatibility with other
+AMD 29K assemblers.
+
+@item .use @var{section name}
+@cindex @code{use} directive, AMD 29K
+Establishes the section and subsection for the following code;
+@var{section name} may be one of @code{.text}, @code{.data},
+@code{.data1}, or @code{.lit}. With one of the first three @var{section
+name} options, @samp{.use} is equivalent to the machine directive
+@var{section name}; the remaining case, @samp{.use .lit}, is the same as
+@samp{.data 200}.
+@end table
+
+@node AMD29K Opcodes, , AMD29K Directives, AMD29K-Dependent
+@subsection Opcodes
+
+@cindex AMD 29K opcodes
+@cindex opcodes for AMD 29K
+@code{as} implements all the standard AMD 29K opcodes. No
+additional pseudo-instructions are needed on this family.
+
+For information on the 29K machine instruction set, see @cite{Am29000
+User's Manual}, Advanced Micro Devices, Inc.
+
+@node H8/300-Dependent, i960-Dependent, AMD29K-Dependent, Machine Dependent
+@section H8/300 Dependent Features
+
+@cindex H8/300 support
+@menu
+* H8/300 Options:: Options
+* H8/300 Syntax:: Syntax
+* H8/300 Floating Point:: Floating Point
+* H8/300 Directives:: H8/300 Machine Directives
+* H8/300 Opcodes:: Opcodes
+@end menu
+
+@node H8/300 Options, H8/300 Syntax, H8/300-Dependent, H8/300-Dependent
+@subsection Options
+
+@cindex H8/300 options (none)
+@cindex options, H8/300 (none)
+@code{as} has no additional command-line options for the Hitachi
+H8/300 family.
+
+@node H8/300 Syntax, H8/300 Floating Point, H8/300 Options, H8/300-Dependent
+@subsection Syntax
+@menu
+* H8/300-Chars:: Special Characters
+* H8/300-Regs:: Register Names
+* H8/300-Addressing:: Addressing Modes
+@end menu
+
+@node H8/300-Chars, H8/300-Regs, H8/300 Syntax, H8/300 Syntax
+@subsubsection Special Characters
+
+@cindex line comment character, H8/300
+@cindex H8/300 line comment character
+@samp{;} is the line comment character.
+
+@cindex line separator, H8/300
+@cindex statement separator, H8/300
+@cindex H8/300 line separator
+@samp{$} can be used instead of a newline to separate statements.
+Therefore @emph{you may not use @samp{$} in symbol names} on the H8/300.
+
+@node H8/300-Regs, H8/300-Addressing, H8/300-Chars, H8/300 Syntax
+@subsubsection Register Names
+
+@cindex H8/300 registers
+@cindex registers, H8/300
+You can use predefined symbols of the form @samp{r@var{n}h} and
+@samp{r@var{n}l} to refer to the H8/300 registers as sixteen 8-bit
+general-purpose registers. @var{n} is a digit from @samp{0} to
+@samp{7}); for instance, both @samp{r0h} and @samp{r7l} are valid
+register names.
+
+You can also use the eight predefined symbols @samp{r@var{n}} to refer
+to the H8/300 registers as 16-bit registers (you must use this form for
+addressing).
+
+The two control registers are called @code{pc} (program counter; a
+16-bit register) and @code{ccr} (condition code register; an 8-bit
+register). @code{r7} is used as the stack pointer, and can also be
+called @code{sp}.
+
+@node H8/300-Addressing, , H8/300-Regs, H8/300 Syntax
+@subsubsection Addressing Modes
+
+@cindex addressing modes, H8/300
+@cindex H8/300 addressing modes
+as understands the following addressing modes for the H8/300:
+@table @code
+@item r@var{n}
+Register direct
+
+@item @@r@var{n}
+Register indirect
+
+@item @@(@var{d}, r@var{n})
+@itemx @@(@var{d}:16, r@var{n})
+Register indirect: 16-bit displacement @var{d} from register @var{n}.
+(You may specify the @samp{:16} for clarity if you wish, but it is not
+required and has no effect.)
+
+@item @@r@var{n}+
+Register indirect with post-increment
+
+@item @@-r@var{n}
+Register indirect with pre-decrement
+
+@item @code{@@}@var{aa}
+@itemx @code{@@}@var{aa}:8
+@itemx @code{@@}@var{aa}:16
+Absolute address @code{aa}. You may specify the @samp{:8} or @samp{:16}
+for clarity, if you wish; but @code{as} neither requires this nor
+uses it---the address size required is taken from context.
+
+@item #@var{xx}
+@itemx #@var{xx}:8
+@itemx #@var{xx}:16
+Immediate data @var{xx}. You may specify the @samp{:8} or @samp{:16}
+for clarity, if you wish; but @code{as} neither requires this nor
+uses it---the data size required is taken from context.
+
+@item @code{@@}@code{@@}@var{aa}
+@itemx @code{@@}@code{@@}@var{aa}:8
+Memory indirect. You may specify the @samp{:8} for clarity, if you
+wish; but @code{as} neither requires this nor uses it.
+@end table
+
+@node H8/300 Floating Point, H8/300 Directives, H8/300 Syntax, H8/300-Dependent
+@subsection Floating Point
+
+@cindex floating point, H8/300 (@sc{ieee})
+@cindex H8/300 floating point (@sc{ieee})
+The H8/300 family uses @sc{ieee} floating-point numbers.
+
+@node H8/300 Directives, H8/300 Opcodes, H8/300 Floating Point, H8/300-Dependent
+@subsection H8/300 Machine Directives
+
+@cindex H8/300 machine directives (none)
+@cindex machine directives, H8/300 (none)
+@cindex @code{word} directive, H8/300
+@cindex @code{int} directive, H8/300
+@code{as} has no machine-dependent directives for the H8/300.
+However, on this platform the @samp{.int} and @samp{.word} directives
+generate 16-bit numbers.
+
+@node H8/300 Opcodes, , H8/300 Directives, H8/300-Dependent
+@subsection Opcodes
+
+@cindex H8/300 opcode summary
+@cindex opcode summary, H8/300
+@cindex mnemonics, H8/300
+@cindex instruction summary, H8/300
+For detailed information on the H8/300 machine instruction set, see
+@cite{H8/300 Series Programming Manual} (Hitachi ADE--602--025).
+
+@code{as} implements all the standard H8/300 opcodes. No additional
+pseudo-instructions are needed on this family.
+
+The following table summarizes the opcodes and their arguments:
+@c kluge due to lack of group outside example
+@page
+@smallexample
+@group
+ Rs @r{source register}
+ Rd @r{destination register}
+ imm @r{immediate data}
+ x:3 @r{a bit (as a number between 0 and 7)}
+ d:8 @r{eight bit displacement from @code{pc}}
+ d:16 @r{sixteen bit displacement from @code{Rs}}
+
+add.b Rs,Rd biand #x:3,Rd
+add.b #imm:8,Rd biand #x:3,@@Rd
+add.w Rs,Rd biand #x:3,@@aa:8
+adds #1,Rd bild #x:3,Rd
+adds #2,Rd bild #x:3,@@Rd
+addx #imm:8,Rd bild #x:3,@@aa:8
+addx Rs,Rd bior #x:3,Rd
+and #imm:8,Rd bior #x:3,@@Rd
+and Rs,Rd bior #x:3,@@aa:8
+andc #imm:8,ccr bist #x:3,Rd
+band #x:3,Rd bist #x:3,@@Rd
+band #x:3,@@Rd bist #x:3,@@aa:8
+bra d:8 bixor #x:3,Rd
+bt d:8 bixor #x:3,@@Rd
+brn d:8 bixor #x:3,@@aa:8
+bf d:8 bld #x:3,Rd
+bhi d:8 bld #x:3,@@Rd
+bls d:8 bld #x:3,@@aa:8
+bcc d:8 bnot #x:3,Rd
+bhs d:8 bnot #x:3,@@Rd
+bcs d:8 bnot #x:3,@@aa:8
+blo d:8 bnot Rs,Rd
+bne d:8 bnot Rs,@@Rd
+beq d:8 bnot Rs,@@aa:8
+bvc d:8 bor #x:3,Rd
+bvs d:8 bor #x:3,@@Rd
+bpl d:8 bor #x:3,@@aa:8
+bmi d:8 bset #x:3,@@Rd
+bge d:8 bset #x:3,@@aa:8
+blt d:8 bset Rs,Rd
+bgt d:8 bset Rs,@@Rd
+ble d:8 bset Rs,@@aa:8
+bclr #x:3,Rd bsr d:8
+bclr #x:3,@@Rd bst #x:3,Rd
+bclr #x:3,@@aa:8 bst #x:3,@@Rd
+bclr Rs,Rd bst #x:3,@@aa:8
+bclr Rs,@@Rd btst #x:3,Rd
+@end group
+@group
+btst #x:3,@@Rd mov.w @@(d:16, Rs),Rd
+btst #x:3,@@aa:8 mov.w @@Rs+,Rd
+btst Rs,Rd mov.w @@aa:16,Rd
+btst Rs,@@Rd mov.w Rs,@@Rd
+btst Rs,@@aa:8 mov.w Rs,@@(d:16, Rd)
+bxor #x:3,Rd mov.w Rs,@@-Rd
+bxor #x:3,@@Rd mov.w Rs,@@aa:16
+bxor #x:3,@@aa:8 movfpe @@aa:16,Rd
+cmp.b #imm:8,Rd movtpe Rs,@@aa:16
+cmp.b Rs,Rd mulxu Rs,Rd
+cmp.w Rs,Rd neg Rs
+daa Rs nop
+das Rs not Rs
+dec Rs or #imm:8,Rd
+divxu Rs,Rd or Rs,Rd
+eepmov orc #imm:8,ccr
+inc Rs pop Rs
+jmp @@Rs push Rs
+jmp @@aa:16 rotl Rs
+jmp @@@@aa rotr Rs
+jsr @@Rs rotxl Rs
+jsr @@aa:16 rotxr Rs
+jsr @@@@aa:8 rte
+ldc #imm:8,ccr rts
+ldc Rs,ccr shal Rs
+mov.b Rs,Rd shar Rs
+mov.b #imm:8,Rd shll Rs
+mov.b @@Rs,Rd shlr Rs
+mov.b @@(d:16, Rs),Rd sleep
+mov.b @@Rs+,Rd stc ccr,Rd
+mov.b @@aa:16,Rd sub.b Rs,Rd
+mov.b @@aa:8,Rd sub.w Rs,Rd
+mov.b Rs,@@Rd subs #1,Rd
+mov.b Rs,@@(d:16, Rd) subs #2,Rd
+mov.b Rs,@@-Rd subx #imm:8,Rd
+mov.b Rs,@@aa:16 subx Rs,Rd
+mov.b Rs,@@aa:8 xor #imm:8,Rd
+mov.w Rs,Rd xor Rs,Rd
+mov.w #imm:16,Rd xorc #imm:8,ccr
+mov.w @@Rs,Rd
+@end group
+@end smallexample
+
+@cindex size suffixes, H8/300
+@cindex H8/300 size suffixes
+Four H8/300 instructions (@code{add}, @code{cmp}, @code{mov},
+@code{sub}) are defined with variants using the suffixes @samp{.b} and
+@samp{.w} to specify the size of a memory operand. @code{as}
+supports these suffixes, but does not require them; since one of the
+operands is always a register, @code{as} can deduce the correct size.
+
+For example, since @code{r0} refers to a 16-bit register,
+@example
+mov r0,@@foo
+@exdent is equivalent to
+mov.w r0,@@foo
+@end example
+
+If you use the size suffixes, @code{as} will issue a warning if
+there's a mismatch between the suffix and the register size.
+
+@node i960-Dependent, M68K-Dependent, H8/300-Dependent, Machine Dependent
+@section Intel 80960 Dependent Features
+
+@cindex i960 support
+@menu
+* Options-i960:: i960 Command-line Options
+* Floating Point-i960:: Floating Point
+* Directives-i960:: i960 Machine Directives
+* Opcodes for i960:: i960 Opcodes
+@end menu
+
+@c FIXME! Add Syntax sec with discussion of bitfields here, at least so
+@c long as they're not turned on for other machines than 960.
+@node Options-i960, Floating Point-i960, i960-Dependent, i960-Dependent
+
+@subsection i960 Command-line Options
+
+@cindex i960 options
+@cindex options, i960
+@table @code
+
+@item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
+@cindex i960 architecture options
+@cindex architecture options, i960
+@cindex @code{-A} options, i960
+Select the 80960 architecture. Instructions or features not supported
+by the selected architecture cause fatal errors.
+
+@samp{-ACA} is equivalent to @samp{-ACA_A}; @samp{-AKC} is equivalent to
+@samp{-AMC}. Synonyms are provided for compatibility with other tools.
+
+If none of these options is specified, @code{as} will generate code for any
+instruction or feature that is supported by @emph{some} version of the
+960 (even if this means mixing architectures!). In principle,
+@code{as} will attempt to deduce the minimal sufficient processor
+type if none is specified; depending on the object code format, the
+processor type may be recorded in the object file. If it is critical
+that the @code{as} output match a specific architecture, specify that
+architecture explicitly.
+
+@item -b
+@cindex @code{-b} option, i960
+@cindex branch recording, i960
+@cindex i960 branch recording
+Add code to collect information about conditional branches taken, for
+later optimization using branch prediction bits. (The conditional branch
+instructions have branch prediction bits in the CA, CB, and CC
+architectures.) If @var{BR} represents a conditional branch instruction,
+the following represents the code generated by the assembler when
+@samp{-b} is specified:
+
+@smallexample
+ call @var{increment routine}
+ .word 0 # pre-counter
+Label: @var{BR}
+ call @var{increment routine}
+ .word 0 # post-counter
+@end smallexample
+
+The counter following a branch records the number of times that branch
+was @emph{not} taken; the differenc between the two counters is the
+number of times the branch @emph{was} taken.
+
+@cindex @code{gbr960}, i960 postprocessor
+@cindex branch statistics table, i960
+A table of every such @code{Label} is also generated, so that the
+external postprocessor @code{gbr960} (supplied by Intel) can locate all
+the counters. This table is always labelled @samp{__BRANCH_TABLE__};
+this is a local symbol to permit collecting statistics for many separate
+object files. The table is word aligned, and begins with a two-word
+header. The first word, initialized to 0, is used in maintaining linked
+lists of branch tables. The second word is a count of the number of
+entries in the table, which follow immediately: each is a word, pointing
+to one of the labels illustrated above.
+
+@c TEXI2ROFF-KILL
+@ifinfo
+@c END TEXI2ROFF-KILL
+@example
+ +------------+------------+------------+ ... +------------+
+ | | | | | |
+ | *NEXT | COUNT: N | *BRLAB 1 | | *BRLAB N |
+ | | | | | |
+ +------------+------------+------------+ ... +------------+
+
+ __BRANCH_TABLE__ layout
+@end example
+@c TEXI2ROFF-KILL
+@end ifinfo
+@tex
+\vskip 1pc
+\line{\leftskip=0pt\hskip\tableindent
+\boxit{2cm}{\tt *NEXT}\boxit{2cm}{\tt COUNT: \it N}\boxit{2cm}{\tt
+*BRLAB 1}\ibox{1cm}{\quad\dots}\boxit{2cm}{\tt *BRLAB \it N}\hfil}
+\centerline{\it {\tt \_\_BRANCH\_TABLE\_\_} layout}
+@end tex
+@c END TEXI2ROFF-KILL
+
+The first word of the header is used to locate multiple branch tables,
+since each object file may contain one. Normally the links are
+maintained with a call to an initialization routine, placed at the
+beginning of each function in the file. The GNU C compiler will
+generate these calls automatically when you give it a @samp{-b} option.
+For further details, see the documentation of @samp{gbr960}.
+
+@item -norelax
+@cindex @code{-norelax} option, i960
+Normally, Compare-and-Branch instructions with targets that require
+displacements greater than 13 bits (or that have external targets) are
+replaced with the corresponding compare (or @samp{chkbit}) and branch
+instructions. You can use the @samp{-norelax} option to specify that
+@code{as} should generate errors instead, if the target displacement
+is larger than 13 bits.
+
+This option does not affect the Compare-and-Jump instructions; the code
+emitted for them is @emph{always} adjusted when necessary (depending on
+displacement size), regardless of whether you use @samp{-norelax}.
+@end table
+
+@node Floating Point-i960, Directives-i960, Options-i960, i960-Dependent
+@subsection Floating Point
+
+@cindex floating point, i960 (@sc{ieee})
+@cindex i960 floating point (@sc{ieee})
+@code{as} generates @sc{ieee} floating-point numbers for the directives
+@samp{.float}, @samp{.double}, @samp{.extended}, and @samp{.single}.
+
+@node Directives-i960, Opcodes for i960, Floating Point-i960, i960-Dependent
+@subsection i960 Machine Directives
+
+@cindex machine directives, i960
+@cindex i960 machine directives
+
+@table @code
+@cindex @code{bss} directive, i960
+@item .bss @var{symbol}, @var{length}, @var{align}
+Reserve @var{length} bytes in the bss section for a local @var{symbol},
+aligned to the power of two specified by @var{align}. @var{length} and
+@var{align} must be positive absolute expressions. This directive
+differs from @samp{.lcomm} only in that it permits you to specify
+an alignment. @xref{Lcomm,,@code{.lcomm}}.
+@end table
+
+@table @code
+@item .extended @var{flonums}
+@cindex @code{extended} directive, i960
+@code{.extended} expects zero or more flonums, separated by commas; for
+each flonum, @samp{.extended} emits an @sc{ieee} extended-format (80-bit)
+floating-point number.
+
+@item .leafproc @var{call-lab}, @var{bal-lab}
+@cindex @code{leafproc} directive, i960
+You can use the @samp{.leafproc} directive in conjunction with the
+optimized @code{callj} instruction to enable faster calls of leaf
+procedures. If a procedure is known to call no other procedures, you
+may define an entry point that skips procedure prolog code (and that does
+not depend on system-supplied saved context), and declare it as the
+@var{bal-lab} using @samp{.leafproc}. If the procedure also has an
+entry point that goes through the normal prolog, you can specify that
+entry point as @var{call-lab}.
+
+A @samp{.leafproc} declaration is meant for use in conjunction with the
+optimized call instruction @samp{callj}; the directive records the data
+needed later to choose between converting the @samp{callj} into a
+@code{bal} or a @code{call}.
+
+@var{call-lab} is optional; if only one argument is present, or if the
+two arguments are identical, the single argument is assumed to be the
+@code{bal} entry point.
+
+@item .sysproc @var{name}, @var{index}
+@cindex @code{sysproc} directive, i960
+The @samp{.sysproc} directive defines a name for a system procedure.
+After you define it using @samp{.sysproc}, you can use @var{name} to
+refer to the system procedure identified by @var{index} when calling
+procedures with the optimized call instruction @samp{callj}.
+
+Both arguments are required; @var{index} must be between 0 and 31
+(inclusive).
+@end table
+
+@node Opcodes for i960, , Directives-i960, i960-Dependent
+@subsection i960 Opcodes
+
+@cindex opcodes, i960
+@cindex i960 opcodes
+All Intel 960 machine instructions are supported;
+@pxref{Options-i960,,i960 Command-line Options} for a discussion of
+selecting the instruction subset for a particular 960
+architecture.@refill
+
+Some opcodes are processed beyond simply emitting a single corresponding
+instruction: @samp{callj}, and Compare-and-Branch or Compare-and-Jump
+instructions with target displacements larger than 13 bits.
+
+@menu
+* callj-i960:: @code{callj}
+* Compare-and-branch-i960:: Compare-and-Branch
+@end menu
+
+@node callj-i960, Compare-and-branch-i960, Opcodes for i960, Opcodes for i960
+@subsubsection @code{callj}
+
+@cindex @code{callj}, i960 pseudo-opcode
+@cindex i960 @code{callj} pseudo-opcode
+You can write @code{callj} to have the assembler or the linker determine
+the most appropriate form of subroutine call: @samp{call},
+@samp{bal}, or @samp{calls}. If the assembly source contains
+enough information---a @samp{.leafproc} or @samp{.sysproc} directive
+defining the operand---then @code{as} will translate the
+@code{callj}; if not, it will simply emit the @code{callj}, leaving it
+for the linker to resolve.
+
+@node Compare-and-branch-i960, , callj-i960, Opcodes for i960
+@subsubsection Compare-and-Branch
+
+@cindex i960 compare and branch instructions
+@cindex compare and branch instructions, i960
+The 960 architectures provide combined Compare-and-Branch instructions
+that permit you to store the branch target in the lower 13 bits of the
+instruction word itself. However, if you specify a branch target far
+enough away that its address won't fit in 13 bits, the assembler can
+either issue an error, or convert your Compare-and-Branch instruction
+into separate instructions to do the compare and the branch.
+
+@cindex compare and jump expansions, i960
+@cindex i960 compare and jump expansions
+Whether @code{as} gives an error or expands the instruction depends
+on two choices you can make: whether you use the @samp{-norelax} option,
+and whether you use a ``Compare and Branch'' instruction or a ``Compare
+and Jump'' instruction. The ``Jump'' instructions are @emph{always}
+expanded if necessary; the ``Branch'' instructions are expanded when
+necessary @emph{unless} you specify @code{-norelax}---in which case
+@code{as} gives an error instead.
+
+These are the Compare-and-Branch instructions, their ``Jump'' variants,
+and the instruction pairs they may expand into:
+
+@c TEXI2ROFF-KILL
+@ifinfo
+@c END TEXI2ROFF-KILL
+@example
+ Compare and
+ Branch Jump Expanded to
+ ------ ------ ------------
+ bbc chkbit; bno
+ bbs chkbit; bo
+ cmpibe cmpije cmpi; be
+ cmpibg cmpijg cmpi; bg
+ cmpibge cmpijge cmpi; bge
+ cmpibl cmpijl cmpi; bl
+ cmpible cmpijle cmpi; ble
+ cmpibno cmpijno cmpi; bno
+ cmpibne cmpijne cmpi; bne
+ cmpibo cmpijo cmpi; bo
+ cmpobe cmpoje cmpo; be
+ cmpobg cmpojg cmpo; bg
+ cmpobge cmpojge cmpo; bge
+ cmpobl cmpojl cmpo; bl
+ cmpoble cmpojle cmpo; ble
+ cmpobne cmpojne cmpo; bne
+@end example
+@c TEXI2ROFF-KILL
+@end ifinfo
+@tex
+\hskip\tableindent
+\halign{\hfil {\tt #}\quad&\hfil {\tt #}\qquad&{\tt #}\hfil\cr
+\omit{\hfil\it Compare and\hfil}\span\omit&\cr
+{\it Branch}&{\it Jump}&{\it Expanded to}\cr
+ bbc& & chkbit; bno\cr
+ bbs& & chkbit; bo\cr
+ cmpibe& cmpije& cmpi; be\cr
+ cmpibg& cmpijg& cmpi; bg\cr
+ cmpibge& cmpijge& cmpi; bge\cr
+ cmpibl& cmpijl& cmpi; bl\cr
+ cmpible& cmpijle& cmpi; ble\cr
+ cmpibno& cmpijno& cmpi; bno\cr
+ cmpibne& cmpijne& cmpi; bne\cr
+ cmpibo& cmpijo& cmpi; bo\cr
+ cmpobe& cmpoje& cmpo; be\cr
+ cmpobg& cmpojg& cmpo; bg\cr
+ cmpobge& cmpojge& cmpo; bge\cr
+ cmpobl& cmpojl& cmpo; bl\cr
+ cmpoble& cmpojle& cmpo; ble\cr
+ cmpobne& cmpojne& cmpo; bne\cr}
+@end tex
+@c END TEXI2ROFF-KILL
+
+@c FIXME! node conds are only sufficient for m68k alone, all, and vintage
+@node M68K-Dependent, Sparc-Dependent, i960-Dependent, Machine Dependent
+@section M680x0 Dependent Features
+
+@cindex M680x0 support
+@menu
+* M68K-Opts:: M680x0 Options
+* M68K-Syntax:: Syntax
+* M68K-Float:: Floating Point
+* M68K-Directives:: 680x0 Machine Directives
+* M68K-opcodes:: Opcodes
+@end menu
+
+@node M68K-Opts, M68K-Syntax, M68K-Dependent, M68K-Dependent
+@subsection M680x0 Options
+
+@cindex options, M680x0
+@cindex M680x0 options
+The Motorola 680x0 version of @code{as} has two machine dependent options.
+One shortens undefined references from 32 to 16 bits, while the
+other is used to tell @code{as} what kind of machine it is
+assembling for.
+
+@cindex @code{-l} option, M680x0
+You can use the @kbd{-l} option to shorten the size of references to
+undefined symbols. If the @kbd{-l} option is not given, references to
+undefined symbols will be a full long (32 bits) wide. (Since @code{as}
+cannot know where these symbols will end up, @code{as} can only allocate
+space for the linker to fill in later. Since @code{as} doesn't know how
+far away these symbols will be, it allocates as much space as it can.)
+If this option is given, the references will only be one word wide (16
+bits). This may be useful if you want the object file to be as small as
+possible, and you know that the relevant symbols will be less than 17
+bits away.
+
+@cindex @code{-m68000} and related options, M680x0
+@cindex architecture options, M680x0
+@cindex M680x0 architecture options
+The 680x0 version of @code{as} is most frequently used to assemble
+programs for the Motorola MC68020 microprocessor. Occasionally it is
+used to assemble programs for the mostly similar, but slightly different
+MC68000 or MC68010 microprocessors. You can give @code{as} the options
+@samp{-m68000}, @samp{-mc68000}, @samp{-m68010}, @samp{-mc68010},
+@samp{-m68020}, and @samp{-mc68020} to tell it what processor is the
+target.
+
+@node M68K-Syntax, M68K-Float, M68K-Opts, M68K-Dependent
+@subsection Syntax
+
+@cindex M680x0 syntax
+@cindex syntax, M680x0
+@cindex M680x0 size modifiers
+@cindex size modifiers, M680x0
+The 680x0 version of @code{as} uses syntax similar to the Sun assembler.
+Size modifiers are appended directly to the end of the opcode without an
+intervening period. For example, write @samp{movl} rather than
+@samp{move.l}.
+
+
+In the following table @dfn{apc} stands for any of the address
+registers (@samp{a0} through @samp{a7}), nothing, (@samp{}), the
+Program Counter (@samp{pc}), or the zero-address relative to the
+program counter (@samp{zpc}).
+
+@cindex M680x0 addressing modes
+@cindex addressing modes, M680x0
+The following addressing modes are understood:
+@table @dfn
+@item Immediate
+@samp{#@var{digits}}
+
+@item Data Register
+@samp{d0} through @samp{d7}
+
+@item Address Register
+@samp{a0} through @samp{a7}
+
+@item Address Register Indirect
+@samp{a0@@} through @samp{a7@@}
+
+@item Address Register Postincrement
+@samp{a0@@+} through @samp{a7@@+}
+
+@item Address Register Predecrement
+@samp{a0@@-} through @samp{a7@@-}
+
+@item Indirect Plus Offset
+@samp{@var{apc}@@(@var{digits})}
+
+@item Index
+@samp{@var{apc}@@(@var{digits},@var{register}:@var{size}:@var{scale})}
+
+or @samp{@var{apc}@@(@var{register}:@var{size}:@var{scale})}
+
+@item Postindex
+@samp{@var{apc}@@(@var{digits})@@(@var{digits},@var{register}:@var{size}:@var{scale})}
+
+or @samp{@var{apc}@@(@var{digits})@@(@var{register}:@var{size}:@var{scale})}
+
+@item Preindex
+@samp{@var{apc}@@(@var{digits},@var{register}:@var{size}:@var{scale})@@(@var{digits})}
+
+or @samp{@var{apc}@@(@var{register}:@var{size}:@var{scale})@@(@var{digits})}
+
+@item Memory Indirect
+@samp{@var{apc}@@(@var{digits})@@(@var{digits})}
+
+@item Absolute
+@samp{@var{symbol}}, or @samp{@var{digits}}
+@ignore
+@c pesch@cygnus.com: gnu, rich concur the following needs careful
+@c research before documenting.
+ , or either of the above followed
+by @samp{:b}, @samp{:w}, or @samp{:l}.
+@end ignore
+@end table
+
+@node M68K-Float, M68K-Directives, M68K-Syntax, M68K-Dependent
+@subsection Floating Point
+
+@cindex floating point, M680x0
+@cindex M680x0 floating point
+@c FIXME is this "not too well tested" crud STILL true?
+The floating point code is not too well tested, and may have
+subtle bugs in it.
+
+Packed decimal (P) format floating literals are not supported.
+Feel free to add the code!
+
+The floating point formats generated by directives are these.
+
+@table @code
+@item .float
+@cindex @code{float} directive, M680x0
+@code{Single} precision floating point constants.
+
+@item .double
+@cindex @code{double} directive, M680x0
+@code{Double} precision floating point constants.
+@end table
+
+There is no directive to produce regions of memory holding
+extended precision numbers, however they can be used as
+immediate operands to floating-point instructions. Adding a
+directive to create extended precision numbers would not be
+hard, but it has not yet seemed necessary.
+
+@node M68K-Directives, M68K-opcodes, M68K-Float, M68K-Dependent
+@subsection 680x0 Machine Directives
+
+@cindex M680x0 directives
+@cindex directives, M680x0
+In order to be compatible with the Sun assembler the 680x0 assembler
+understands the following directives.
+
+@table @code
+@item .data1
+@cindex @code{data1} directive, M680x0
+This directive is identical to a @code{.data 1} directive.
+
+@item .data2
+@cindex @code{data2} directive, M680x0
+This directive is identical to a @code{.data 2} directive.
+
+@item .even
+@cindex @code{even} directive, M680x0
+This directive is identical to a @code{.align 1} directive.
+@c Is this true? does it work???
+
+@item .skip
+@cindex @code{skip} directive, M680x0
+This directive is identical to a @code{.space} directive.
+@end table
+
+@node M68K-opcodes, , M68K-Directives, M68K-Dependent
+@subsection Opcodes
+
+@cindex M680x0 opcodes
+@cindex opcodes, M680x0
+@cindex instruction set, M680x0
+@c pesch@cygnus.com: I don't see any point in the following
+@c paragraph. Bugs are bugs; how does saying this
+@c help anyone?
+@ignore
+Danger: Several bugs have been found in the opcode table (and
+fixed). More bugs may exist. Be careful when using obscure
+instructions.
+@end ignore
+
+@menu
+* M68K-Branch:: Branch Improvement
+* M68K-Chars:: Special Characters
+@end menu
+
+@node M68K-Branch, M68K-Chars, M68K-opcodes, M68K-opcodes
+@subsubsection Branch Improvement
+
+@cindex pseudo-opcodes, M680x0
+@cindex M680x0 pseudo-opcodes
+@cindex branch improvement, M680x0
+@cindex M680x0 branch improvement
+Certain pseudo opcodes are permitted for branch instructions.
+They expand to the shortest branch instruction that will reach the
+target. Generally these mnemonics are made by substituting @samp{j} for
+@samp{b} at the start of a Motorola mnemonic.
+
+The following table summarizes the pseudo-operations. A @code{*} flags
+cases that are more fully described after the table:
+
+@smallexample
+ Displacement
+ +---------------------------------------------------------
+ | 68020 68000/10
+Pseudo-Op |BYTE WORD LONG LONG non-PC relative
+ +---------------------------------------------------------
+ jbsr |bsrs bsr bsrl jsr jsr
+ jra |bras bra bral jmp jmp
+* jXX |bXXs bXX bXXl bNXs;jmpl bNXs;jmp
+* dbXX |dbXX dbXX dbXX; bra; jmpl
+* fjXX |fbXXw fbXXw fbXXl fbNXw;jmp
+
+XX: condition
+NX: negative of condition XX
+
+@end smallexample
+@center @code{*}---see full description below
+
+@table @code
+@item jbsr
+@itemx jra
+These are the simplest jump pseudo-operations; they always map to one
+particular machine instruction, depending on the displacement to the
+branch target.
+
+@item j@var{XX}
+Here, @samp{j@var{XX}} stands for an entire family of pseudo-operations,
+where @var{XX} is a conditional branch or condition-code test. The full
+list of pseudo-ops in this family is:
+@smallexample
+ jhi jls jcc jcs jne jeq jvc
+ jvs jpl jmi jge jlt jgt jle
+@end smallexample
+
+For the cases of non-PC relative displacements and long displacements on
+the 68000 or 68010, @code{as} will issue a longer code fragment in terms of
+@var{NX}, the opposite condition to @var{XX}:
+@smallexample
+ j@var{XX} foo
+@end smallexample
+gives
+@smallexample
+ b@var{NX}s oof
+ jmp foo
+ oof:
+@end smallexample
+
+@item db@var{XX}
+The full family of pseudo-operations covered here is
+@smallexample
+ dbhi dbls dbcc dbcs dbne dbeq dbvc
+ dbvs dbpl dbmi dbge dblt dbgt dble
+ dbf dbra dbt
+@end smallexample
+
+Other than for word and byte displacements, when the source reads
+@samp{db@var{XX} foo}, @code{as} will emit
+@smallexample
+ db@var{XX} oo1
+ bra oo2
+ oo1:jmpl foo
+ oo2:
+@end smallexample
+
+@item fj@var{XX}
+This family includes
+@smallexample
+ fjne fjeq fjge fjlt fjgt fjle fjf
+ fjt fjgl fjgle fjnge fjngl fjngle fjngt
+ fjnle fjnlt fjoge fjogl fjogt fjole fjolt
+ fjor fjseq fjsf fjsne fjst fjueq fjuge
+ fjugt fjule fjult fjun
+@end smallexample
+
+For branch targets that are not PC relative, @code{as} emits
+@smallexample
+ fb@var{NX} oof
+ jmp foo
+ oof:
+@end smallexample
+when it encounters @samp{fj@var{XX} foo}.
+
+@end table
+
+@node M68K-Chars, , M68K-Branch, M68K-opcodes
+@subsubsection Special Characters
+
+@cindex special characters, M680x0
+@cindex M680x0 immediate character
+@cindex immediate character, M680x0
+@cindex M680x0 line comment character
+@cindex line comment character, M680x0
+@cindex comments, M680x0
+The immediate character is @samp{#} for Sun compatibility. The
+line-comment character is @samp{|}. If a @samp{#} appears at the
+beginning of a line, it is treated as a comment unless it looks like
+@samp{# line file}, in which case it is treated normally.
+
+@node Sparc-Dependent, i386-Dependent, M68K-Dependent, Machine Dependent
+@section SPARC Dependent Features
+
+@cindex SPARC support
+@menu
+* Sparc-Opts:: Options
+* Sparc-Float:: Floating Point
+* Sparc-Directives:: Sparc Machine Directives
+@end menu
+
+@node Sparc-Opts, Sparc-Float, Sparc-Dependent, Sparc-Dependent
+@subsection Options
+
+@cindex options for SPARC (none)
+@cindex SPARC options (none)
+The Sparc has no machine dependent options.
+
+@ignore
+@c FIXME: (sparc) Fill in "syntax" section!
+@c subsection syntax
+I don't know anything about Sparc syntax. Someone who does
+will have to write this section.
+@end ignore
+
+@node Sparc-Float, Sparc-Directives, Sparc-Opts, Sparc-Dependent
+@subsection Floating Point
+
+@cindex floating point, SPARC (@sc{ieee})
+@cindex SPARC floating point (@sc{ieee})
+The Sparc uses @sc{ieee} floating-point numbers.
+
+@node Sparc-Directives, , Sparc-Float, Sparc-Dependent
+@subsection Sparc Machine Directives
+
+@cindex SPARC machine directives
+@cindex machine directives, SPARC
+The Sparc version of @code{as} supports the following additional
+machine directives:
+
+@table @code
+@item .common
+@cindex @code{common} directive, SPARC
+This must be followed by a symbol name, a positive number, and
+@code{"bss"}. This behaves somewhat like @code{.comm}, but the
+syntax is different.
+
+@item .half
+@cindex @code{half} directive, SPARC
+This is functionally identical to @code{.short}.
+
+@item .proc
+@cindex @code{proc} directive, SPARC
+This directive is ignored. Any text following it on the same
+line is also ignored.
+
+@item .reserve
+@cindex @code{reserve} directive, SPARC
+This must be followed by a symbol name, a positive number, and
+@code{"bss"}. This behaves somewhat like @code{.lcomm}, but the
+syntax is different.
+
+@item .seg
+@cindex @code{seg} directive, SPARC
+This must be followed by @code{"text"}, @code{"data"}, or
+@code{"data1"}. It behaves like @code{.text}, @code{.data}, or
+@code{.data 1}.
+
+@item .skip
+@cindex @code{skip} directive, SPARC
+This is functionally identical to the @code{.space} directive.
+
+@item .word
+@cindex @code{word} directive, SPARC
+On the Sparc, the .word directive produces 32 bit values,
+instead of the 16 bit values it produces on many other machines.
+@end table
+
+@c FIXME! Conditionalize for all combinations in this section
+@node i386-Dependent, , Sparc-Dependent, Machine Dependent
+@section 80386 Dependent Features
+
+@cindex i386 support
+@cindex i80306 support
+@menu
+* i386-Options:: Options
+* i386-Syntax:: AT&T Syntax versus Intel Syntax
+* i386-Opcodes:: Opcode Naming
+* i386-Regs:: Register Naming
+* i386-prefixes:: Opcode Prefixes
+* i386-Memory:: Memory References
+* i386-jumps:: Handling of Jump Instructions
+* i386-Float:: Floating Point
+* i386-Notes:: Notes
+@end menu
+
+@node i386-Options, i386-Syntax, i386-Dependent, i386-Dependent
+@subsection Options
+
+@cindex options for i386 (none)
+@cindex i386 options (none)
+The 80386 has no machine dependent options.
+
+@node i386-Syntax, i386-Opcodes, i386-Options, i386-Dependent
+@subsection AT&T Syntax versus Intel Syntax
+
+@cindex i386 syntax compatibility
+@cindex syntax compatibility, i386
+In order to maintain compatibility with the output of @code{gcc},
+@code{as} supports AT&T System V/386 assembler syntax. This is quite
+different from Intel syntax. We mention these differences because
+almost all 80386 documents used only Intel syntax. Notable differences
+between the two syntaxes are:
+
+@itemize @bullet
+@item
+@cindex immediate operands, i386
+@cindex i386 immediate operands
+@cindex register operands, i386
+@cindex i386 register operands
+@cindex jump/call operands, i386
+@cindex i386 jump/call operands
+@cindex operand delimiters, i386
+AT&T immediate operands are preceded by @samp{$}; Intel immediate
+operands are undelimited (Intel @samp{push 4} is AT&T @samp{pushl $4}).
+AT&T register operands are preceded by @samp{%}; Intel register operands
+are undelimited. AT&T absolute (as opposed to PC relative) jump/call
+operands are prefixed by @samp{*}; they are undelimited in Intel syntax.
+
+@item
+@cindex i386 source, destination operands
+@cindex source, destination operands; i386
+AT&T and Intel syntax use the opposite order for source and destination
+operands. Intel @samp{add eax, 4} is @samp{addl $4, %eax}. The
+@samp{source, dest} convention is maintained for compatibility with
+previous Unix assemblers.
+
+@item
+@cindex opcode suffixes, i386
+@cindex sizes operands, i386
+@cindex i386 size suffixes
+In AT&T syntax the size of memory operands is determined from the last
+character of the opcode name. Opcode suffixes of @samp{b}, @samp{w},
+and @samp{l} specify byte (8-bit), word (16-bit), and long (32-bit)
+memory references. Intel syntax accomplishes this by prefixes memory
+operands (@emph{not} the opcodes themselves) with @samp{byte ptr},
+@samp{word ptr}, and @samp{dword ptr}. Thus, Intel @samp{mov al, byte
+ptr @var{foo}} is @samp{movb @var{foo}, %al} in AT&T syntax.
+
+@item
+@cindex return instructions, i386
+@cindex i386 jump, call, return
+Immediate form long jumps and calls are
+@samp{lcall/ljmp $@var{section}, $@var{offset}} in AT&T syntax; the
+Intel syntax is
+@samp{call/jmp far @var{section}:@var{offset}}. Also, the far return
+instruction
+is @samp{lret $@var{stack-adjust}} in AT&T syntax; Intel syntax is
+@samp{ret far @var{stack-adjust}}.
+
+@item
+@cindex sections, i386
+@cindex i386 sections
+The AT&T assembler does not provide support for multiple section
+programs. Unix style systems expect all programs to be single sections.
+@end itemize
+
+@node i386-Opcodes, i386-Regs, i386-Syntax, i386-Dependent
+@subsection Opcode Naming
+
+@cindex i386 opcode naming
+@cindex opcode naming, i386
+Opcode names are suffixed with one character modifiers which specify the
+size of operands. The letters @samp{b}, @samp{w}, and @samp{l} specify
+byte, word, and long operands. If no suffix is specified by an
+instruction and it contains no memory operands then @code{as} tries to
+fill in the missing suffix based on the destination register operand
+(the last one by convention). Thus, @samp{mov %ax, %bx} is equivalent
+to @samp{movw %ax, %bx}; also, @samp{mov $1, %bx} is equivalent to
+@samp{movw $1, %bx}. Note that this is incompatible with the AT&T Unix
+assembler which assumes that a missing opcode suffix implies long
+operand size. (This incompatibility does not affect compiler output
+since compilers always explicitly specify the opcode suffix.)
+
+Almost all opcodes have the same names in AT&T and Intel format. There
+are a few exceptions. The sign extend and zero extend instructions need
+two sizes to specify them. They need a size to sign/zero extend
+@emph{from} and a size to zero extend @emph{to}. This is accomplished
+by using two opcode suffixes in AT&T syntax. Base names for sign extend
+and zero extend are @samp{movs@dots{}} and @samp{movz@dots{}} in AT&T
+syntax (@samp{movsx} and @samp{movzx} in Intel syntax). The opcode
+suffixes are tacked on to this base name, the @emph{from} suffix before
+the @emph{to} suffix. Thus, @samp{movsbl %al, %edx} is AT&T syntax for
+``move sign extend @emph{from} %al @emph{to} %edx.'' Possible suffixes,
+thus, are @samp{bl} (from byte to long), @samp{bw} (from byte to word),
+and @samp{wl} (from word to long).
+
+@cindex conversion instructions, i386
+@cindex i386 conversion instructions
+The Intel-syntax conversion instructions
+
+@itemize @bullet
+@item
+@samp{cbw} --- sign-extend byte in @samp{%al} to word in @samp{%ax},
+
+@item
+@samp{cwde} --- sign-extend word in @samp{%ax} to long in @samp{%eax},
+
+@item
+@samp{cwd} --- sign-extend word in @samp{%ax} to long in @samp{%dx:%ax},
+
+@item
+@samp{cdq} --- sign-extend dword in @samp{%eax} to quad in @samp{%edx:%eax},
+@end itemize
+
+@noindent
+are called @samp{cbtw}, @samp{cwtl}, @samp{cwtd}, and @samp{cltd} in
+AT&T naming. @code{as} accepts either naming for these instructions.
+
+@cindex jump instructions, i386
+@cindex call instructions, i386
+Far call/jump instructions are @samp{lcall} and @samp{ljmp} in
+AT&T syntax, but are @samp{call far} and @samp{jump far} in Intel
+convention.
+
+@node i386-Regs, i386-prefixes, i386-Opcodes, i386-Dependent
+@subsection Register Naming
+
+@cindex i386 registers
+@cindex registers, i386
+Register operands are always prefixes with @samp{%}. The 80386 registers
+consist of
+
+@itemize @bullet
+@item
+the 8 32-bit registers @samp{%eax} (the accumulator), @samp{%ebx},
+@samp{%ecx}, @samp{%edx}, @samp{%edi}, @samp{%esi}, @samp{%ebp} (the
+frame pointer), and @samp{%esp} (the stack pointer).
+
+@item
+the 8 16-bit low-ends of these: @samp{%ax}, @samp{%bx}, @samp{%cx},
+@samp{%dx}, @samp{%di}, @samp{%si}, @samp{%bp}, and @samp{%sp}.
+
+@item
+the 8 8-bit registers: @samp{%ah}, @samp{%al}, @samp{%bh},
+@samp{%bl}, @samp{%ch}, @samp{%cl}, @samp{%dh}, and @samp{%dl} (These
+are the high-bytes and low-bytes of @samp{%ax}, @samp{%bx},
+@samp{%cx}, and @samp{%dx})
+
+@item
+the 6 section registers @samp{%cs} (code section), @samp{%ds}
+(data section), @samp{%ss} (stack section), @samp{%es}, @samp{%fs},
+and @samp{%gs}.
+
+@item
+the 3 processor control registers @samp{%cr0}, @samp{%cr2}, and
+@samp{%cr3}.
+
+@item
+the 6 debug registers @samp{%db0}, @samp{%db1}, @samp{%db2},
+@samp{%db3}, @samp{%db6}, and @samp{%db7}.
+
+@item
+the 2 test registers @samp{%tr6} and @samp{%tr7}.
+
+@item
+the 8 floating point register stack @samp{%st} or equivalently
+@samp{%st(0)}, @samp{%st(1)}, @samp{%st(2)}, @samp{%st(3)},
+@samp{%st(4)}, @samp{%st(5)}, @samp{%st(6)}, and @samp{%st(7)}.
+@end itemize
+
+@node i386-prefixes, i386-Memory, i386-Regs, i386-Dependent
+@subsection Opcode Prefixes
+
+@cindex i386 opcode prefixes
+@cindex opcode prefixes, i386
+@cindex prefixes, i386
+Opcode prefixes are used to modify the following opcode. They are used
+to repeat string instructions, to provide section overrides, to perform
+bus lock operations, and to give operand and address size (16-bit
+operands are specified in an instruction by prefixing what would
+normally be 32-bit operands with a ``operand size'' opcode prefix).
+Opcode prefixes are usually given as single-line instructions with no
+operands, and must directly precede the instruction they act upon. For
+example, the @samp{scas} (scan string) instruction is repeated with:
+@smallexample
+ repne
+ scas
+@end smallexample
+
+Here is a list of opcode prefixes:
+
+@itemize @bullet
+@item
+@cindex section override prefixes, i386
+Section override prefixes @samp{cs}, @samp{ds}, @samp{ss}, @samp{es},
+@samp{fs}, @samp{gs}. These are automatically added by specifying
+using the @var{section}:@var{memory-operand} form for memory references.
+
+@item
+@cindex size prefixes, i386
+Operand/Address size prefixes @samp{data16} and @samp{addr16}
+change 32-bit operands/addresses into 16-bit operands/addresses. Note
+that 16-bit addressing modes (i.e. 8086 and 80286 addressing modes)
+are not supported (yet).
+
+@item
+@cindex bus lock prefixes, i386
+@cindex inhibiting interrupts, i386
+The bus lock prefix @samp{lock} inhibits interrupts during
+execution of the instruction it precedes. (This is only valid with
+certain instructions; see a 80386 manual for details).
+
+@item
+@cindex coprocessor wait, i386
+The wait for coprocessor prefix @samp{wait} waits for the
+coprocessor to complete the current instruction. This should never be
+needed for the 80386/80387 combination.
+
+@item
+@cindex repeat prefixes, i386
+The @samp{rep}, @samp{repe}, and @samp{repne} prefixes are added
+to string instructions to make them repeat @samp{%ecx} times.
+@end itemize
+
+@node i386-Memory, i386-jumps, i386-prefixes, i386-Dependent
+@subsection Memory References
+
+@cindex i386 memory references
+@cindex memory references, i386
+An Intel syntax indirect memory reference of the form
+
+@smallexample
+@var{section}:[@var{base} + @var{index}*@var{scale} + @var{disp}]
+@end smallexample
+
+@noindent
+is translated into the AT&T syntax
+
+@smallexample
+@var{section}:@var{disp}(@var{base}, @var{index}, @var{scale})
+@end smallexample
+
+@noindent
+where @var{base} and @var{index} are the optional 32-bit base and
+index registers, @var{disp} is the optional displacement, and
+@var{scale}, taking the values 1, 2, 4, and 8, multiplies @var{index}
+to calculate the address of the operand. If no @var{scale} is
+specified, @var{scale} is taken to be 1. @var{section} specifies the
+optional section register for the memory operand, and may override the
+default section register (see a 80386 manual for section register
+defaults). Note that section overrides in AT&T syntax @emph{must} have
+be preceded by a @samp{%}. If you specify a section override which
+coincides with the default section register, @code{as} will @emph{not}
+output any section register override prefixes to assemble the given
+instruction. Thus, section overrides can be specified to emphasize which
+section register is used for a given memory operand.
+
+Here are some examples of Intel and AT&T style memory references:
+
+@table @asis
+@item AT&T: @samp{-4(%ebp)}, Intel: @samp{[ebp - 4]}
+@var{base} is @samp{%ebp}; @var{disp} is @samp{-4}. @var{section} is
+missing, and the default section is used (@samp{%ss} for addressing with
+@samp{%ebp} as the base register). @var{index}, @var{scale} are both missing.
+
+@item AT&T: @samp{foo(,%eax,4)}, Intel: @samp{[foo + eax*4]}
+@var{index} is @samp{%eax} (scaled by a @var{scale} 4); @var{disp} is
+@samp{foo}. All other fields are missing. The section register here
+defaults to @samp{%ds}.
+
+@item AT&T: @samp{foo(,1)}; Intel @samp{[foo]}
+This uses the value pointed to by @samp{foo} as a memory operand.
+Note that @var{base} and @var{index} are both missing, but there is only
+@emph{one} @samp{,}. This is a syntactic exception.
+
+@item AT&T: @samp{%gs:foo}; Intel @samp{gs:foo}
+This selects the contents of the variable @samp{foo} with section
+register @var{section} being @samp{%gs}.
+@end table
+
+Absolute (as opposed to PC relative) call and jump operands must be
+prefixed with @samp{*}. If no @samp{*} is specified, @code{as} will
+always choose PC relative addressing for jump/call labels.
+
+Any instruction that has a memory operand @emph{must} specify its size (byte,
+word, or long) with an opcode suffix (@samp{b}, @samp{w}, or @samp{l},
+respectively).
+
+@node i386-jumps, i386-Float, i386-Memory, i386-Dependent
+@subsection Handling of Jump Instructions
+
+@cindex jump optimization, i386
+@cindex i386 jump optimization
+Jump instructions are always optimized to use the smallest possible
+displacements. This is accomplished by using byte (8-bit) displacement
+jumps whenever the target is sufficiently close. If a byte displacement
+is insufficient a long (32-bit) displacement is used. We do not support
+word (16-bit) displacement jumps (i.e. prefixing the jump instruction
+with the @samp{addr16} opcode prefix), since the 80386 insists upon masking
+@samp{%eip} to 16 bits after the word displacement is added.
+
+Note that the @samp{jcxz}, @samp{jecxz}, @samp{loop}, @samp{loopz},
+@samp{loope}, @samp{loopnz} and @samp{loopne} instructions only come in
+byte displacements, so that it is possible that use of these
+instructions (@code{gcc} does not use them) will cause the assembler to
+print an error message (and generate incorrect code). The AT&T 80386
+assembler tries to get around this problem by expanding @samp{jcxz foo} to
+@smallexample
+ jcxz cx_zero
+ jmp cx_nonzero
+cx_zero: jmp foo
+cx_nonzero:
+@end smallexample
+
+@node i386-Float, i386-Notes, i386-jumps, i386-Dependent
+@subsection Floating Point
+
+@cindex i386 floating point
+@cindex floating point, i386
+All 80387 floating point types except packed BCD are supported.
+(BCD support may be added without much difficulty). These data
+types are 16-, 32-, and 64- bit integers, and single (32-bit),
+double (64-bit), and extended (80-bit) precision floating point.
+Each supported type has an opcode suffix and a constructor
+associated with it. Opcode suffixes specify operand's data
+types. Constructors build these data types into memory.
+
+@itemize @bullet
+@item
+@cindex @code{float} directive, i386
+@cindex @code{single} directive, i386
+@cindex @code{double} directive, i386
+@cindex @code{tfloat} directive, i386
+Floating point constructors are @samp{.float} or @samp{.single},
+@samp{.double}, and @samp{.tfloat} for 32-, 64-, and 80-bit formats.
+These correspond to opcode suffixes @samp{s}, @samp{l}, and @samp{t}.
+@samp{t} stands for temporary real, and that the 80387 only supports
+this format via the @samp{fldt} (load temporary real to stack top) and
+@samp{fstpt} (store temporary real and pop stack) instructions.
+
+@item
+@cindex @code{word} directive, i386
+@cindex @code{long} directive, i386
+@cindex @code{int} directive, i386
+@cindex @code{quad} directive, i386
+Integer constructors are @samp{.word}, @samp{.long} or @samp{.int}, and
+@samp{.quad} for the 16-, 32-, and 64-bit integer formats. The corresponding
+opcode suffixes are @samp{s} (single), @samp{l} (long), and @samp{q}
+(quad). As with the temporary real format the 64-bit @samp{q} format is
+only present in the @samp{fildq} (load quad integer to stack top) and
+@samp{fistpq} (store quad integer and pop stack) instructions.
+@end itemize
+
+Register to register operations do not require opcode suffixes,
+so that @samp{fst %st, %st(1)} is equivalent to @samp{fstl %st, %st(1)}.
+
+@cindex i386 @code{fwait} instruction
+@cindex @code{fwait instruction}, i386
+Since the 80387 automatically synchronizes with the 80386 @samp{fwait}
+instructions are almost never needed (this is not the case for the
+80286/80287 and 8086/8087 combinations). Therefore, @code{as} suppresses
+the @samp{fwait} instruction whenever it is implicitly selected by one
+of the @samp{fn@dots{}} instructions. For example, @samp{fsave} and
+@samp{fnsave} are treated identically. In general, all the @samp{fn@dots{}}
+instructions are made equivalent to @samp{f@dots{}} instructions. If
+@samp{fwait} is desired it must be explicitly coded.
+
+@node i386-Notes, , i386-Float, i386-Dependent
+@subsection Notes
+
+@cindex i386 @code{mul}, @code{imul} instructions
+@cindex @code{mul} instruction, i386
+@cindex @code{imul} instruction, i386
+There is some trickery concerning the @samp{mul} and @samp{imul}
+instructions that deserves mention. The 16-, 32-, and 64-bit expanding
+multiplies (base opcode @samp{0xf6}; extension 4 for @samp{mul} and 5
+for @samp{imul}) can be output only in the one operand form. Thus,
+@samp{imul %ebx, %eax} does @emph{not} select the expanding multiply;
+the expanding multiply would clobber the @samp{%edx} register, and this
+would confuse @code{gcc} output. Use @samp{imul %ebx} to get the
+64-bit product in @samp{%edx:%eax}.
+
+We have added a two operand form of @samp{imul} when the first operand
+is an immediate mode expression and the second operand is a register.
+This is just a shorthand, so that, multiplying @samp{%eax} by 69, for
+example, can be done with @samp{imul $69, %eax} rather than @samp{imul
+$69, %eax, %eax}.
+
+
+@node Copying, Index, Machine Dependent, Top
+@unnumbered GNU GENERAL PUBLIC LICENSE
+
+@cindex license
+@cindex GPL
+@cindex copying @code{as}
+@center Version 2, June 1991
+
+@display
+Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
+675 Mass Ave, Cambridge, MA 02139, USA
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+@end display
+
+@unnumberedsec Preamble
+
+ The licenses for most software are designed to take away your
+freedom to share and change it. By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software---to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.) You can apply it to
+your programs, too.
+
+ When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+ To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+ For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have. You must make sure that they, too, receive or can get the
+source code. And you must show them these terms so they know their
+rights.
+
+ We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+ Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+ Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+ The precise terms and conditions for copying, distribution and
+modification follow.
+
+@iftex
+@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+@end iftex
+@ifinfo
+@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+@end ifinfo
+
+@enumerate
+@item
+This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License. The ``Program'', below,
+refers to any such program or work, and a ``work based on the Program''
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language. (Hereinafter, translation is included without limitation in
+the term ``modification''.) Each licensee is addressed as ``you''.
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope. The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+@item
+You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+@item
+You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+@enumerate a
+@item
+You must cause the modified files to carry prominent notices
+stating that you changed the files and the date of any change.
+
+@item
+You must cause any work that you distribute or publish, that in
+whole or in part contains or is derived from the Program or any
+part thereof, to be licensed as a whole at no charge to all third
+parties under the terms of this License.
+
+@item
+If the modified program normally reads commands interactively
+when run, you must cause it, when started running for such
+interactive use in the most ordinary way, to print or display an
+announcement including an appropriate copyright notice and a
+notice that there is no warranty (or else, saying that you provide
+a warranty) and that users may redistribute the program under
+these conditions, and telling the user how to view a copy of this
+License. (Exception: if the Program itself is interactive but
+does not normally print such an announcement, your work based on
+the Program is not required to print an announcement.)
+@end enumerate
+
+These requirements apply to the modified work as a whole. If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works. But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+@item
+You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+@enumerate a
+@item
+Accompany it with the complete corresponding machine-readable
+source code, which must be distributed under the terms of Sections
+1 and 2 above on a medium customarily used for software interchange; or,
+
+@item
+Accompany it with a written offer, valid for at least three
+years, to give any third party, for a charge no more than your
+cost of physically performing source distribution, a complete
+machine-readable copy of the corresponding source code, to be
+distributed under the terms of Sections 1 and 2 above on a medium
+customarily used for software interchange; or,
+
+@item
+Accompany it with the information you received as to the offer
+to distribute corresponding source code. (This alternative is
+allowed only for noncommercial distribution and only if you
+received the program in object code or executable form with such
+an offer, in accord with Subsection b above.)
+@end enumerate
+
+The source code for a work means the preferred form of the work for
+making modifications to it. For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable. However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+@item
+You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License. Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+@item
+You are not required to accept this License, since you have not
+signed it. However, nothing else grants you permission to modify or
+distribute the Program or its derivative works. These actions are
+prohibited by law if you do not accept this License. Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+@item
+Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions. You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+@item
+If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License. If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all. For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
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+
+It is not the purpose of this section to induce you to infringe any
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+integrity of the free software distribution system, which is
+implemented by public license practices. Many people have made
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+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+@item
+If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded. In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+@item
+The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time. Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number. If the Program
+specifies a version number of this License which applies to it and ``any
+later version'', you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation. If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+@item
+If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission. For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this. Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+@iftex
+@heading NO WARRANTY
+@end iftex
+@ifinfo
+@center NO WARRANTY
+@end ifinfo
+
+@item
+BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+@item
+IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+@end enumerate
+
+@iftex
+@heading END OF TERMS AND CONDITIONS
+@end iftex
+@ifinfo
+@center END OF TERMS AND CONDITIONS
+@end ifinfo
+
+@page
+@unnumberedsec Applying These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the ``copyright'' line and a pointer to where the full notice is found.
+
+@smallexample
+@var{one line to give the program's name and an idea of what it does.}
+Copyright (C) 19@var{yy} @var{name of author}
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the
+Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.
+@end smallexample
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+@smallexample
+Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
+Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+type `show w'. This is free software, and you are welcome
+to redistribute it under certain conditions; type `show c'
+for details.
+@end smallexample
+
+The hypothetical commands @samp{show w} and @samp{show c} should show
+the appropriate parts of the General Public License. Of course, the
+commands you use may be called something other than @samp{show w} and
+@samp{show c}; they could even be mouse-clicks or menu items---whatever
+suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a ``copyright disclaimer'' for the program, if
+necessary. Here is a sample; alter the names:
+
+@smallexample
+Yoyodyne, Inc., hereby disclaims all copyright interest in
+the program `Gnomovision' (which makes passes at compilers)
+written by James Hacker.
+
+@var{signature of Ty Coon}, 1 April 1989
+Ty Coon, President of Vice
+@end smallexample
+
+This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Library General
+Public License instead of this License.
+
+@node Index, , Copying, Top
+@unnumbered Index
+
+@printindex cp
+
+@summarycontents
+@contents
+@bye
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