binutils-gdb/gas/frags.c

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1999-05-03 09:29:11 +02:00
/* frags.c - manage frags -
Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 97, 1998
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, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
#include "as.h"
#include "subsegs.h"
#include "obstack.h"
extern fragS zero_address_frag;
extern fragS bss_address_frag;
/* Initialization for frag routines. */
void
frag_init ()
{
zero_address_frag.fr_type = rs_fill;
bss_address_frag.fr_type = rs_fill;
}
/* Allocate a frag on the specified obstack.
Call this routine from everywhere else, so that all the weird alignment
hackery can be done in just one place. */
fragS *
frag_alloc (ob)
struct obstack *ob;
{
fragS *ptr;
int oalign;
(void) obstack_alloc (ob, 0);
oalign = obstack_alignment_mask (ob);
obstack_alignment_mask (ob) = 0;
ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG);
obstack_alignment_mask (ob) = oalign;
memset (ptr, 0, SIZEOF_STRUCT_FRAG);
return ptr;
}
/*
* frag_grow()
*
* Try to augment current frag by nchars chars.
* If there is no room, close of the current frag with a ".fill 0"
* and begin a new frag. Unless the new frag has nchars chars available
* do not return. Do not set up any fields of *now_frag.
*/
void
frag_grow (nchars)
unsigned int nchars;
{
if (obstack_room (&frchain_now->frch_obstack) < nchars)
{
unsigned int n;
long oldc;
frag_wane (frag_now);
frag_new (0);
oldc = frchain_now->frch_obstack.chunk_size;
frchain_now->frch_obstack.chunk_size = 2 * nchars + SIZEOF_STRUCT_FRAG;
while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars)
{
frag_wane (frag_now);
frag_new (0);
}
frchain_now->frch_obstack.chunk_size = oldc;
}
if (obstack_room (&frchain_now->frch_obstack) < nchars)
as_fatal (_("Can't extend frag %d. chars"), nchars);
}
/*
* frag_new()
*
* Call this to close off a completed frag, and start up a new (empty)
* frag, in the same subsegment as the old frag.
* [frchain_now remains the same but frag_now is updated.]
* Because this calculates the correct value of fr_fix by
* looking at the obstack 'frags', it needs to know how many
* characters at the end of the old frag belong to (the maximal)
* fr_var: the rest must belong to fr_fix.
* It doesn't actually set up the old frag's fr_var: you may have
* set fr_var == 1, but allocated 10 chars to the end of the frag:
* in this case you pass old_frags_var_max_size == 10.
*
* Make a new frag, initialising some components. Link new frag at end
* of frchain_now.
*/
void
frag_new (old_frags_var_max_size)
/* Number of chars (already allocated on obstack frags) in
variable_length part of frag. */
int old_frags_var_max_size;
{
fragS *former_last_fragP;
frchainS *frchP;
assert (frchain_now->frch_last == frag_now);
/* Fix up old frag's fr_fix. */
frag_now->fr_fix = frag_now_fix () - old_frags_var_max_size;
/* Make sure its type is valid. */
assert (frag_now->fr_type != 0);
/* This will align the obstack so the next struct we allocate on it
will begin at a correct boundary. */
obstack_finish (&frchain_now->frch_obstack);
frchP = frchain_now;
know (frchP);
former_last_fragP = frchP->frch_last;
assert (former_last_fragP != 0);
assert (former_last_fragP == frag_now);
frag_now = frag_alloc (&frchP->frch_obstack);
as_where (&frag_now->fr_file, &frag_now->fr_line);
/* Generally, frag_now->points to an address rounded up to next
alignment. However, characters will add to obstack frags
IMMEDIATELY after the struct frag, even if they are not starting
at an alignment address. */
former_last_fragP->fr_next = frag_now;
frchP->frch_last = frag_now;
#ifndef NO_LISTING
{
extern struct list_info_struct *listing_tail;
frag_now->line = listing_tail;
}
#endif
assert (frchain_now->frch_last == frag_now);
frag_now->fr_next = NULL;
} /* frag_new() */
/*
* frag_more()
*
* Start a new frag unless we have n more chars of room in the current frag.
* Close off the old frag with a .fill 0.
*
* Return the address of the 1st char to write into. Advance
* frag_now_growth past the new chars.
*/
char *
frag_more (nchars)
int nchars;
{
register char *retval;
if (now_seg == absolute_section)
{
as_bad (_("attempt to allocate data in absolute section"));
subseg_set (text_section, 0);
}
if (mri_common_symbol != NULL)
{
as_bad (_("attempt to allocate data in common section"));
mri_common_symbol = NULL;
}
frag_grow (nchars);
retval = obstack_next_free (&frchain_now->frch_obstack);
obstack_blank_fast (&frchain_now->frch_obstack, nchars);
return (retval);
} /* frag_more() */
/*
* frag_var()
*
* Start a new frag unless we have max_chars more chars of room in the current frag.
* Close off the old frag with a .fill 0.
*
* Set up a machine_dependent relaxable frag, then start a new frag.
* Return the address of the 1st char of the var part of the old frag
* to write into.
*/
char *
frag_var (type, max_chars, var, subtype, symbol, offset, opcode)
relax_stateT type;
int max_chars;
int var;
relax_substateT subtype;
symbolS *symbol;
offsetT offset;
char *opcode;
{
register char *retval;
frag_grow (max_chars);
retval = obstack_next_free (&frchain_now->frch_obstack);
obstack_blank_fast (&frchain_now->frch_obstack, max_chars);
frag_now->fr_var = var;
frag_now->fr_type = type;
frag_now->fr_subtype = subtype;
frag_now->fr_symbol = symbol;
frag_now->fr_offset = offset;
frag_now->fr_opcode = opcode;
#ifdef USING_CGEN
frag_now->fr_cgen.insn = 0;
frag_now->fr_cgen.opindex = 0;
frag_now->fr_cgen.opinfo = 0;
#endif
#ifdef TC_FRAG_INIT
TC_FRAG_INIT (frag_now);
#endif
as_where (&frag_now->fr_file, &frag_now->fr_line);
frag_new (max_chars);
return (retval);
}
/*
* frag_variant()
*
* OVE: This variant of frag_var assumes that space for the tail has been
* allocated by caller.
* No call to frag_grow is done.
*/
char *
frag_variant (type, max_chars, var, subtype, symbol, offset, opcode)
relax_stateT type;
int max_chars;
int var;
relax_substateT subtype;
symbolS *symbol;
offsetT offset;
char *opcode;
{
register char *retval;
retval = obstack_next_free (&frchain_now->frch_obstack);
frag_now->fr_var = var;
frag_now->fr_type = type;
frag_now->fr_subtype = subtype;
frag_now->fr_symbol = symbol;
frag_now->fr_offset = offset;
frag_now->fr_opcode = opcode;
#ifdef USING_CGEN
frag_now->fr_cgen.insn = 0;
frag_now->fr_cgen.opindex = 0;
frag_now->fr_cgen.opinfo = 0;
#endif
#ifdef TC_FRAG_INIT
TC_FRAG_INIT (frag_now);
#endif
as_where (&frag_now->fr_file, &frag_now->fr_line);
frag_new (max_chars);
return (retval);
} /* frag_variant() */
/*
* frag_wane()
*
* Reduce the variable end of a frag to a harmless state.
*/
void
frag_wane (fragP)
register fragS *fragP;
{
fragP->fr_type = rs_fill;
fragP->fr_offset = 0;
fragP->fr_var = 0;
}
/* Make an alignment frag. The size of this frag will be adjusted to
force the next frag to have the appropriate alignment. ALIGNMENT
is the power of two to which to align. FILL_CHARACTER is the
character to use to fill in any bytes which are skipped. MAX is
the maximum number of characters to skip when doing the alignment,
or 0 if there is no maximum. */
void
frag_align (alignment, fill_character, max)
int alignment;
int fill_character;
int max;
{
if (now_seg == absolute_section)
{
addressT new_off;
new_off = ((abs_section_offset + alignment - 1)
&~ ((1 << alignment) - 1));
if (max == 0 || new_off - abs_section_offset <= (addressT) max)
abs_section_offset = new_off;
}
else
{
char *p;
p = frag_var (rs_align, 1, 1, (relax_substateT) max,
(symbolS *) 0, (offsetT) alignment, (char *) 0);
*p = fill_character;
}
}
/* Make an alignment frag like frag_align, but fill with a repeating
pattern rather than a single byte. ALIGNMENT is the power of two
to which to align. FILL_PATTERN is the fill pattern to repeat in
the bytes which are skipped. N_FILL is the number of bytes in
FILL_PATTERN. MAX is the maximum number of characters to skip when
doing the alignment, or 0 if there is no maximum. */
void
frag_align_pattern (alignment, fill_pattern, n_fill, max)
int alignment;
const char *fill_pattern;
int n_fill;
int max;
{
char *p;
p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max,
(symbolS *) 0, (offsetT) alignment, (char *) 0);
memcpy (p, fill_pattern, n_fill);
}
addressT
frag_now_fix ()
{
if (now_seg == absolute_section)
return abs_section_offset;
return (addressT) ((char*) obstack_next_free (&frchain_now->frch_obstack)
- frag_now->fr_literal);
}
void
frag_append_1_char (datum)
int datum;
{
if (obstack_room (&frchain_now->frch_obstack) <= 1)
{
frag_wane (frag_now);
frag_new (0);
}
obstack_1grow (&frchain_now->frch_obstack, datum);
}
/* end of frags.c */