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.file "wm_shrx.S"
/*
* wm_shrx.S
*
* 64 bit right shift functions
*
* Call from C as:
* unsigned shrx(void *arg1, unsigned arg2)
* and
* unsigned shrxs(void *arg1, unsigned arg2)
*
*
* Copyright (C) 1992,1993,1994
* W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
* Australia. E-mail billm@vaxc.cc.monash.edu.au
* All rights reserved.
*
* This copyright notice covers the redistribution and use of the
* FPU emulator developed by W. Metzenthen. It covers only its use
* in the 386BSD, FreeBSD and NetBSD operating systems. Any other
* use is not permitted under this copyright.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must include information specifying
* that source code for the emulator is freely available and include
* either:
* a) an offer to provide the source code for a nominal distribution
* fee, or
* b) list at least two alternative methods whereby the source
* can be obtained, e.g. a publically accessible bulletin board
* and an anonymous ftp site from which the software can be
* downloaded.
* 3. All advertising materials specifically mentioning features or use of
* this emulator must acknowledge that it was developed by W. Metzenthen.
* 4. The name of W. Metzenthen may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* The purpose of this copyright, based upon the Berkeley copyright, is to
* ensure that the covered software remains freely available to everyone.
*
* The software (with necessary differences) is also available, but under
* the terms of the GNU copyleft, for the Linux operating system and for
* the djgpp ms-dos extender.
*
* W. Metzenthen June 1994.
*
*
* $Id: wm_shrx.s,v 1.3 1994/06/10 07:45:03 rich Exp $
*
*/
#include <gnu/i386/fpemul/fpu_asm.h>
.text
.align 2,144
/*---------------------------------------------------------------------------+
| unsigned shrx(void *arg1, unsigned arg2) |
| |
| Extended shift right function. |
| Fastest for small shifts. |
| Shifts the 64 bit quantity pointed to by the first arg (arg1) |
| right by the number of bits specified by the second arg (arg2). |
| Forms a 96 bit quantity from the 64 bit arg and eax: |
| [ 64 bit arg ][ eax ] |
| shift right ---------> |
| The eax register is initialized to 0 before the shifting. |
| Results returned in the 64 bit arg and eax. |
+---------------------------------------------------------------------------*/
.globl _shrx
_shrx:
push %ebp
movl %esp,%ebp
pushl %esi
movl PARAM2,%ecx
movl PARAM1,%esi
cmpl $32,%ecx /* shrd only works for 0..31 bits */
jnc L_more_than_31
/* less than 32 bits */
pushl %ebx
movl (%esi),%ebx /* lsl */
movl 4(%esi),%edx /* msl */
xorl %eax,%eax /* extension */
shrd %cl,%ebx,%eax
shrd %cl,%edx,%ebx
shr %cl,%edx
movl %ebx,(%esi)
movl %edx,4(%esi)
popl %ebx
popl %esi
leave
ret
L_more_than_31:
cmpl $64,%ecx
jnc L_more_than_63
subb $32,%cl
movl (%esi),%eax /* lsl */
movl 4(%esi),%edx /* msl */
shrd %cl,%edx,%eax
shr %cl,%edx
movl %edx,(%esi)
movl $0,4(%esi)
popl %esi
leave
ret
L_more_than_63:
cmpl $96,%ecx
jnc L_more_than_95
subb $64,%cl
movl 4(%esi),%eax /* msl */
shr %cl,%eax
xorl %edx,%edx
movl %edx,(%esi)
movl %edx,4(%esi)
popl %esi
leave
ret
L_more_than_95:
xorl %eax,%eax
movl %eax,(%esi)
movl %eax,4(%esi)
popl %esi
leave
ret
/*---------------------------------------------------------------------------+
| unsigned shrxs(void *arg1, unsigned arg2) |
| |
| Extended shift right function (optimized for small floating point |
| integers). |
| Shifts the 64 bit quantity pointed to by the first arg (arg1) |
| right by the number of bits specified by the second arg (arg2). |
| Forms a 96 bit quantity from the 64 bit arg and eax: |
| [ 64 bit arg ][ eax ] |
| shift right ---------> |
| The eax register is initialized to 0 before the shifting. |
| The lower 8 bits of eax are lost and replaced by a flag which is |
| set (to 0x01) if any bit, apart from the first one, is set in the |
| part which has been shifted out of the arg. |
| Results returned in the 64 bit arg and eax. |
+---------------------------------------------------------------------------*/
.globl _shrxs
_shrxs:
push %ebp
movl %esp,%ebp
pushl %esi
pushl %ebx
movl PARAM2,%ecx
movl PARAM1,%esi
cmpl $64,%ecx /* shrd only works for 0..31 bits */
jnc Ls_more_than_63
cmpl $32,%ecx /* shrd only works for 0..31 bits */
jc Ls_less_than_32
/* We got here without jumps by assuming that the most common requirement
is for small integers */
/* Shift by [32..63] bits */
subb $32,%cl
movl (%esi),%eax /* lsl */
movl 4(%esi),%edx /* msl */
xorl %ebx,%ebx
shrd %cl,%eax,%ebx
shrd %cl,%edx,%eax
shr %cl,%edx
orl %ebx,%ebx /* test these 32 bits */
setne %bl
test $0x7fffffff,%eax /* and 31 bits here */
setne %bh
orw %bx,%bx /* Any of the 63 bit set ? */
setne %al
movl %edx,(%esi)
movl $0,4(%esi)
popl %ebx
popl %esi
leave
ret
/* Shift by [0..31] bits */
Ls_less_than_32:
movl (%esi),%ebx /* lsl */
movl 4(%esi),%edx /* msl */
xorl %eax,%eax /* extension */
shrd %cl,%ebx,%eax
shrd %cl,%edx,%ebx
shr %cl,%edx
test $0x7fffffff,%eax /* only need to look at eax here */
setne %al
movl %ebx,(%esi)
movl %edx,4(%esi)
popl %ebx
popl %esi
leave
ret
/* Shift by [64..95] bits */
Ls_more_than_63:
cmpl $96,%ecx
jnc Ls_more_than_95
subb $64,%cl
movl (%esi),%ebx /* lsl */
movl 4(%esi),%eax /* msl */
xorl %edx,%edx /* extension */
shrd %cl,%ebx,%edx
shrd %cl,%eax,%ebx
shr %cl,%eax
orl %ebx,%edx
setne %bl
test $0x7fffffff,%eax /* only need to look at eax here */
setne %bh
orw %bx,%bx
setne %al
xorl %edx,%edx
movl %edx,(%esi) /* set to zero */
movl %edx,4(%esi) /* set to zero */
popl %ebx
popl %esi
leave
ret
Ls_more_than_95:
/* Shift by [96..inf) bits */
xorl %eax,%eax
movl (%esi),%ebx
orl 4(%esi),%ebx
setne %al
xorl %ebx,%ebx
movl %ebx,(%esi)
movl %ebx,4(%esi)
popl %ebx
popl %esi
leave
ret
|
