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/* cond.c - conditional assembly pseudo-ops, and .include
Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
This file is part of GAS, the GNU Assembler.
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.
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 GAS; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#ifndef lint
static char rcsid[] = "$Id: cond.c,v 1.2 1994/12/23 22:36:03 nate Exp $";
#endif
#include "as.h"
#include "obstack.h"
/* This is allocated to grow and shrink as .ifdef/.endif pairs are scanned. */
struct obstack cond_obstack;
struct file_line
{
char *file;
unsigned int line;
}; /* file_line */
/* This is what we push and pop. */
struct conditional_frame
{
struct file_line if_file_line; /* the source file & line number of the "if" */
struct file_line else_file_line; /* the source file & line of the "else" */
struct conditional_frame *previous_cframe;
int else_seen; /* have we seen an else yet? */
int ignoring; /* if we are currently ignoring input. */
int dead_tree; /* if a conditional at a higher level is ignoring input. */
}; /* conditional_frame */
static void initialize_cframe PARAMS ((struct conditional_frame *cframe));
static struct conditional_frame *current_cframe = NULL;
void
s_ifdef (arg)
int arg;
{
register char *name; /* points to name of symbol */
register struct symbol *symbolP; /* Points to symbol */
struct conditional_frame cframe;
SKIP_WHITESPACE (); /* Leading whitespace is part of operand. */
name = input_line_pointer;
if (!is_name_beginner (*name))
{
as_bad ("invalid identifier for \".ifdef\"");
obstack_1grow (&cond_obstack, 0);
}
else
{
get_symbol_end ();
++input_line_pointer;
symbolP = symbol_find (name);
initialize_cframe (&cframe);
cframe.ignoring = cframe.dead_tree || !((symbolP != 0) ^ arg);
current_cframe = (struct conditional_frame *) obstack_copy (&cond_obstack, &cframe, sizeof (cframe));
} /* if a valid identifyer name */
return;
} /* s_ifdef() */
void
s_if (arg)
int arg;
{
expressionS operand;
struct conditional_frame cframe;
SKIP_WHITESPACE (); /* Leading whitespace is part of operand. */
expression (&operand);
#ifdef notyet
if (operand.X_op != O_constant)
as_bad ("non-constant expression in \".if\" statement");
#else
if (operand.X_add_symbol != NULL || operand.X_subtract_symbol != NULL) {
as_bad("non-constant expression in \".if\" statement");
} /* bad condition */
#endif
/* If the above error is signaled, this will dispatch
using an undefined result. No big deal. */
initialize_cframe (&cframe);
cframe.ignoring = cframe.dead_tree || !((operand.X_add_number != 0) ^ arg);
current_cframe = (struct conditional_frame *) obstack_copy (&cond_obstack, &cframe, sizeof (cframe));
return;
} /* s_if() */
void
s_endif (arg)
int arg;
{
struct conditional_frame *hold;
if (current_cframe == NULL)
{
as_bad ("\".endif\" without \".if\"");
}
else
{
hold = current_cframe;
current_cframe = current_cframe->previous_cframe;
obstack_free (&cond_obstack, hold);
} /* if one pop too many */
return;
} /* s_endif() */
void
s_else (arg)
int arg;
{
if (current_cframe == NULL)
{
as_bad (".else without matching .if - ignored");
}
else if (current_cframe->else_seen)
{
as_bad ("duplicate \"else\" - ignored");
as_bad_where (current_cframe->else_file_line.file,
current_cframe->else_file_line.line,
"here is the previous \"else\"");
as_bad_where (current_cframe->if_file_line.file,
current_cframe->if_file_line.line,
"here is the previous \"if\"");
}
else
{
as_where (¤t_cframe->else_file_line.file,
¤t_cframe->else_file_line.line);
if (!current_cframe->dead_tree)
{
current_cframe->ignoring = !current_cframe->ignoring;
} /* if not a dead tree */
current_cframe->else_seen = 1;
} /* if error else do it */
return;
} /* s_else() */
void
s_ifeqs (arg)
int arg;
{
as_bad ("ifeqs not implemented.");
return;
} /* s_ifeqs() */
void
s_end (arg)
int arg;
{
return;
} /* s_end() */
int
ignore_input ()
{
/* We cannot ignore certain pseudo ops. */
if (input_line_pointer[-1] == '.'
&& ((input_line_pointer[0] == 'i'
&& (!strncmp (input_line_pointer, "if", 2)
|| !strncmp (input_line_pointer, "ifdef", 5)
|| !strncmp (input_line_pointer, "ifndef", 6)))
|| (input_line_pointer[0] == 'e'
&& (!strncmp (input_line_pointer, "else", 4)
|| !strncmp (input_line_pointer, "endif", 5)))))
{
return 0;
}
return ((current_cframe != NULL) && (current_cframe->ignoring));
} /* ignore_input() */
static void
initialize_cframe (cframe)
struct conditional_frame *cframe;
{
memset (cframe, 0, sizeof (*cframe));
as_where (&cframe->if_file_line.file,
&cframe->if_file_line.line);
cframe->previous_cframe = current_cframe;
cframe->dead_tree = current_cframe != NULL && current_cframe->ignoring;
return;
} /* initialize_cframe() */
/*
* Local Variables:
* fill-column: 131
* comment-column: 0
* End:
*/
/* end of cond.c */
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