292 lines
7.9 KiB
C
292 lines
7.9 KiB
C
/* frags.c - manage frags -
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Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc.
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This file is part of GAS, the GNU Assembler.
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GAS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GAS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GAS; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include "as.h"
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#include "subsegs.h"
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#include "obstack.h"
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struct obstack frags; /* All, and only, frags live here. */
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fragS zero_address_frag = {
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0, /* fr_address */
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NULL, /* fr_next */
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0, /* fr_fix */
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0, /* fr_var */
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0, /* fr_symbol */
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0, /* fr_offset */
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NULL, /* fr_opcode */
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rs_fill, /* fr_type */
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0, /* fr_subtype */
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0, /* fr_pcrel_adjust */
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0, /* fr_bsr */
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0 /* fr_literal [0] */
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};
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fragS bss_address_frag = {
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0, /* fr_address. Gets filled in to make up
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sy_value-s. */
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NULL, /* fr_next */
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0, /* fr_fix */
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0, /* fr_var */
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0, /* fr_symbol */
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0, /* fr_offset */
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NULL, /* fr_opcode */
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rs_fill, /* fr_type */
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0, /* fr_subtype */
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0, /* fr_pcrel_adjust */
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0, /* fr_bsr */
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0 /* fr_literal [0] */
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};
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/*
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* frag_grow()
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*
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* Internal.
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* Try to augment current frag by nchars chars.
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* If there is no room, close of the current frag with a ".fill 0"
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* and begin a new frag. Unless the new frag has nchars chars available
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* do not return. Do not set up any fields of *now_frag.
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*/
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static void frag_grow(nchars)
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unsigned int nchars;
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{
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if (obstack_room (&frags) < nchars) {
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unsigned int n,oldn;
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long oldc;
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frag_wane(frag_now);
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frag_new(0);
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oldn=(unsigned)-1;
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oldc=frags.chunk_size;
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frags.chunk_size=2*nchars;
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while((n=obstack_room(&frags))<nchars && n<oldn) {
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frag_wane(frag_now);
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frag_new(0);
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oldn=n;
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}
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frags.chunk_size=oldc;
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}
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if (obstack_room (&frags) < nchars)
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as_fatal("Can't extend frag %d. chars", nchars);
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} /* frag_grow() */
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/*
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* frag_new()
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*
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* Call this to close off a completed frag, and start up a new (empty)
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* frag, in the same subsegment as the old frag.
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* [frchain_now remains the same but frag_now is updated.]
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* Because this calculates the correct value of fr_fix by
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* looking at the obstack 'frags', it needs to know how many
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* characters at the end of the old frag belong to (the maximal)
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* fr_var: the rest must belong to fr_fix.
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* It doesn't actually set up the old frag's fr_var: you may have
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* set fr_var == 1, but allocated 10 chars to the end of the frag:
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* in this case you pass old_frags_var_max_size == 10.
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*
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* Make a new frag, initialising some components. Link new frag at end
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* of frchain_now.
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*/
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void frag_new(old_frags_var_max_size)
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int old_frags_var_max_size; /* Number of chars (already allocated on
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obstack frags) */
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/* in variable_length part of frag. */
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{
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register fragS * former_last_fragP;
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/* char *throw_away_pointer; JF unused */
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register frchainS * frchP;
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long tmp; /* JF */
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frag_now->fr_fix = (char *) (obstack_next_free (&frags)) -
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(frag_now->fr_literal) - old_frags_var_max_size;
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/* Fix up old frag's fr_fix. */
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obstack_finish (&frags);
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/* This will align the obstack so the */
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/* next struct we allocate on it will */
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/* begin at a correct boundary. */
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frchP = frchain_now;
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know (frchP);
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former_last_fragP = frchP->frch_last;
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know (former_last_fragP);
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know (former_last_fragP == frag_now);
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obstack_blank (&frags, SIZEOF_STRUCT_FRAG);
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/* We expect this will begin at a correct */
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/* boundary for a struct. */
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tmp=obstack_alignment_mask(&frags);
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obstack_alignment_mask(&frags)=0; /* Turn off alignment */
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/* If we ever hit a machine
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where strings must be
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aligned, we Lose Big */
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frag_now=(fragS *)obstack_finish(&frags);
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obstack_alignment_mask(&frags)=tmp; /* Restore alignment */
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/* Just in case we don't get zero'd bytes */
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bzero(frag_now, SIZEOF_STRUCT_FRAG);
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/* obstack_unaligned_done (&frags, &frag_now); */
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/* know (frags.obstack_c_next_free == frag_now->fr_literal); */
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/* Generally, frag_now->points to an */
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/* address rounded up to next alignment. */
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/* However, characters will add to obstack */
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/* frags IMMEDIATELY after the struct frag, */
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/* even if they are not starting at an */
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/* alignment address. */
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former_last_fragP->fr_next = frag_now;
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frchP->frch_last = frag_now;
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#ifndef NO_LISTING
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{
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extern struct list_info_struct *listing_tail;
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frag_now->line = listing_tail;
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}
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#endif
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frag_now->fr_next = NULL;
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} /* frag_new() */
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/*
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* frag_more()
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*
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* Start a new frag unless we have n more chars of room in the current frag.
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* Close off the old frag with a .fill 0.
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*
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* Return the address of the 1st char to write into. Advance
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* frag_now_growth past the new chars.
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*/
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char *frag_more (nchars)
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int nchars;
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{
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register char *retval;
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frag_grow (nchars);
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retval = obstack_next_free (&frags);
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obstack_blank_fast (&frags, nchars);
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return (retval);
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} /* frag_more() */
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/*
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* frag_var()
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*
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* Start a new frag unless we have max_chars more chars of room in the current frag.
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* Close off the old frag with a .fill 0.
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*
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* Set up a machine_dependent relaxable frag, then start a new frag.
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* Return the address of the 1st char of the var part of the old frag
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* to write into.
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*/
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char *frag_var(type, max_chars, var, subtype, symbol, offset, opcode)
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relax_stateT type;
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int max_chars;
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int var;
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relax_substateT subtype;
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symbolS *symbol;
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long offset;
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char *opcode;
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{
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register char *retval;
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frag_grow (max_chars);
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retval = obstack_next_free (&frags);
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obstack_blank_fast (&frags, max_chars);
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frag_now->fr_var = var;
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frag_now->fr_type = type;
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frag_now->fr_subtype = subtype;
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frag_now->fr_symbol = symbol;
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frag_now->fr_offset = offset;
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frag_now->fr_opcode = opcode;
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/* default these to zero. */
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frag_now->fr_pcrel_adjust = 0;
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frag_now->fr_bsr = 0;
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frag_new (max_chars);
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return (retval);
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} /* frag_var() */
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/*
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* frag_variant()
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*
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* OVE: This variant of frag_var assumes that space for the tail has been
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* allocated by caller.
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* No call to frag_grow is done.
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* Two new arguments have been added.
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*/
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char *frag_variant(type, max_chars, var, subtype, symbol, offset, opcode, pcrel_adjust,bsr)
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relax_stateT type;
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int max_chars;
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int var;
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relax_substateT subtype;
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symbolS *symbol;
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long offset;
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char *opcode;
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int pcrel_adjust;
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char bsr;
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{
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register char *retval;
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/* frag_grow (max_chars); */
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retval = obstack_next_free (&frags);
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/* obstack_blank_fast (&frags, max_chars); */ /* OVE: so far the only diff */
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frag_now->fr_var = var;
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frag_now->fr_type = type;
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frag_now->fr_subtype = subtype;
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frag_now->fr_symbol = symbol;
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frag_now->fr_offset = offset;
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frag_now->fr_opcode = opcode;
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frag_now->fr_pcrel_adjust = pcrel_adjust;
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frag_now->fr_bsr = bsr;
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frag_new (max_chars);
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return (retval);
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} /* frag_variant() */
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/*
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* frag_wane()
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*
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* Reduce the variable end of a frag to a harmless state.
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*/
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void frag_wane(fragP)
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register fragS * fragP;
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{
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fragP->fr_type = rs_fill;
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fragP->fr_offset = 0;
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fragP->fr_var = 0;
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}
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/*
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* frag_align()
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*
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* Make a frag for ".align foo,bar". Call is "frag_align (foo,bar);".
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* Foo & bar are absolute integers.
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*
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* Call to close off the current frag with a ".align", then start a new
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* (so far empty) frag, in the same subsegment as the last frag.
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*/
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void frag_align(alignment, fill_character)
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int alignment;
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int fill_character;
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{
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*(frag_var (rs_align, 1, 1, (relax_substateT)0, (symbolS *)0,
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(long)alignment, (char *)0)) = fill_character;
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} /* frag_align() */
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/* end of frags.c */
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