314 lines
9.0 KiB
C
314 lines
9.0 KiB
C
/* subsegs.c - subsegments -
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Copyright (C) 1987, 1990, 1991, 1992 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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/*
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* Segments & sub-segments.
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*/
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#ifndef lint
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static char rcsid[] = "$Id: subsegs.c,v 1.4 1995/03/21 15:27:12 mycroft Exp $";
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#endif
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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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#ifdef MANY_SEGMENTS
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segment_info_type segment_info[SEG_MAXIMUM_ORDINAL];
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frchainS* frchain_root,
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* frchain_now;
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#else
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frchainS* frchain_root,
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* frchain_now, /* Commented in "subsegs.h". */
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* data0_frchainP;
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#endif
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char * const /* in: segT out: char* */
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seg_name[] = {
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"absolute",
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#ifdef MANY_SEGMENTS
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"e0","e1","e2","e3","e4","e5","e6","e7","e8","e9",
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#else
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"text",
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"data",
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"bss",
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#endif
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"unknown",
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"absent",
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"pass1",
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"ASSEMBLER-INTERNAL-LOGIC-ERROR!",
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"bignum/flonum",
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"difference",
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"debug",
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"transfert vector preload",
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"transfert vector postload",
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"register",
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"",
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}; /* Used by error reporters, dumpers etc. */
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void
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subsegs_begin()
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{
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/* Check table(s) seg_name[], seg_N_TYPE[] is in correct order */
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#ifdef MANY_SEGMENTS
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#else
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know(SEG_ABSOLUTE == 0);
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know(SEG_TEXT == 1);
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know(SEG_DATA == 2);
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know(SEG_BSS == 3);
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know(SEG_UNKNOWN == 4);
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know(SEG_ABSENT == 5);
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know(SEG_PASS1 == 6);
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know(SEG_GOOF == 7);
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know(SEG_BIG == 8);
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know(SEG_DIFFERENCE == 9);
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know(SEG_DEBUG == 10);
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know(SEG_NTV == 11);
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know(SEG_PTV == 12);
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know(SEG_REGISTER == 13);
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know(SEG_MAXIMUM_ORDINAL == SEG_REGISTER );
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/* know(segment_name(SEG_MAXIMUM_ORDINAL + 1)[0] == 0);*/
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#endif
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obstack_begin(&frags, 5000);
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frchain_root = NULL;
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frchain_now = NULL; /* Warn new_subseg() that we are booting. */
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/* Fake up 1st frag. */
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/* It won't be used=> is ok if obstack... */
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/* pads the end of it for alignment. */
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frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
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memset(frag_now, SIZEOF_STRUCT_FRAG, 0);
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/* This 1st frag will not be in any frchain. */
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/* We simply give subseg_new somewhere to scribble. */
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now_subseg = 42; /* Lie for 1st call to subseg_new. */
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#ifdef MANY_SEGMENTS
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{
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int i;
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for (i = SEG_E0; i < SEG_UNKNOWN; i++) {
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subseg_new(i, 0);
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segment_info[i].frchainP = frchain_now;
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}
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}
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#else
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subseg_new(SEG_DATA, 0); /* .data 0 */
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data0_frchainP = frchain_now;
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#endif
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}
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/*
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* subseg_change()
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*
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* Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
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* subsegment. If we are already in the correct subsegment, change nothing.
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* This is used eg as a worker for subseg_new [which does make a new frag_now]
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* and for changing segments after we have read the source. We construct eg
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* fixSs even after the source file is read, so we do have to keep the
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* segment context correct.
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*/
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void
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subseg_change (seg, subseg)
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register segT seg;
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register int subseg;
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{
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now_seg = seg;
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now_subseg = subseg;
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know(SEG_NORMAL(seg));
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#ifdef MANY_SEGMENTS
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seg_fix_rootP = &segment_info[seg].fix_root;
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seg_fix_tailP = &segment_info[seg].fix_tail;
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#else
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switch (seg) {
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case SEG_DATA:
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seg_fix_rootP = &data_fix_root;
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seg_fix_tailP = &data_fix_tail;
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break;
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case SEG_TEXT:
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seg_fix_rootP = &text_fix_root;
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seg_fix_tailP = &text_fix_tail;
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break;
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case SEG_BSS:
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seg_fix_rootP = &bss_fix_root;
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seg_fix_tailP = &bss_fix_tail;
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break;
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}
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#endif
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}
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/*
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* subseg_new()
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*
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* If you attempt to change to the current subsegment, nothing happens.
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*
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* In: segT, subsegT code for new subsegment.
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* frag_now -> incomplete frag for current subsegment.
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* If frag_now == NULL, then there is no old, incomplete frag, so
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* the old frag is not closed off.
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*
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* Out: now_subseg, now_seg updated.
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* Frchain_now points to the (possibly new) struct frchain for this
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* sub-segment.
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* Frchain_root updated if needed.
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*/
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void
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subseg_new (seg, subseg) /* begin assembly for a new sub-segment */
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register segT seg; /* SEG_DATA or SEG_TEXT */
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register subsegT subseg;
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{
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long tmp; /* JF for obstack alignment hacking */
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know(SEG_NORMAL(seg));
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if (seg != now_seg || subseg != now_subseg)
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{ /* we just changed sub-segments */
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register frchainS * frcP; /* crawl frchain chain */
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register frchainS** lastPP; /* address of last pointer */
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frchainS *newP; /* address of new frchain */
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register fragS *former_last_fragP;
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register fragS *new_fragP;
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if (frag_now) /* If not bootstrapping. */
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{
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frag_now->fr_fix = obstack_next_free(& frags) - frag_now->fr_literal;
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frag_wane(frag_now); /* Close off any frag in old subseg. */
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}
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/*
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* It would be nice to keep an obstack for each subsegment, if we swap
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* subsegments a lot. Hence we would have much fewer frag_wanes().
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*/
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{
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obstack_finish( &frags);
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/*
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* If we don't do the above, the next object we put on obstack frags
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* will appear to start at the fr_literal of the current frag.
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* Also, above ensures that the next object will begin on a
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* address that is aligned correctly for the engine that runs
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* this program.
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*/
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}
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subseg_change (seg, (int)subseg);
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/*
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* Attempt to find or make a frchain for that sub seg.
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* Crawl along chain of frchainSs, begins @ frchain_root.
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* If we need to make a frchainS, link it into correct
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* position of chain rooted in frchain_root.
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*/
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for (frcP = * (lastPP = & frchain_root);
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frcP
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&& (int)(frcP->frch_seg) <= (int)seg;
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frcP = * ( lastPP = & frcP->frch_next)
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)
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{
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if ( (int)(frcP->frch_seg) == (int)seg
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&& frcP->frch_subseg >= subseg)
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{
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break;
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}
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}
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/*
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* frcP: Address of the 1st frchainS in correct segment with
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* frch_subseg >= subseg.
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* We want to either use this frchainS, or we want
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* to insert a new frchainS just before it.
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*
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* If frcP == NULL, then we are at the end of the chain
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* of frchainS-s. A NULL frcP means we fell off the end
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* of the chain looking for a
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* frch_subseg >= subseg, so we
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* must make a new frchainS.
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*
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* If we ever maintain a pointer to
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* the last frchainS in the chain, we change that pointer
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* ONLY when frcP == NULL.
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*
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* lastPP: Address of the pointer with value frcP;
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* Never NULL.
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* May point to frchain_root.
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*
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*/
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if ( ! frcP
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|| ( (int)(frcP->frch_seg) > (int)seg
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|| frcP->frch_subseg > subseg)) /* Kinky logic only works with 2 segments. */
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{
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/*
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* This should be the only code that creates a frchainS.
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*/
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newP=(frchainS *)obstack_alloc(&frags,sizeof(frchainS));
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memset(newP, sizeof(frchainS), 0);
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/* This begines on a good boundary */
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/* because a obstack_done() preceeded it. */
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/* It implies an obstack_done(), so we */
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/* expect the next object allocated to */
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/* begin on a correct boundary. */
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*lastPP = newP;
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newP->frch_next = frcP; /* perhaps NULL */
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(frcP = newP)->frch_subseg = subseg;
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newP->frch_seg = seg;
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newP->frch_last = NULL;
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}
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/*
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* Here with frcP->ing to the frchainS for subseg.
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*/
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frchain_now = frcP;
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/*
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* Make a fresh frag for the subsegment.
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*/
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/* We expect this to happen on a correct */
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/* boundary since it was proceeded by a */
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/* obstack_done(). */
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tmp=obstack_alignment_mask(&frags); /* JF disable alignment */
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obstack_alignment_mask(&frags)=0;
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frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
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obstack_alignment_mask(&frags)=tmp;
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/* know(frags.obstack_c_next_free == frag_now->fr_literal); */
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/* But we want any more chars to come */
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/* immediately after the structure we just made. */
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new_fragP = frag_now;
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new_fragP->fr_next = NULL;
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/*
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* Append new frag to current frchain.
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*/
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former_last_fragP = frcP->frch_last;
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if (former_last_fragP)
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{
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know( former_last_fragP->fr_next == NULL );
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know( frchain_now->frch_root );
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former_last_fragP->fr_next = new_fragP;
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}
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else
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{
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frcP->frch_root = new_fragP;
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}
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frcP->frch_last = new_fragP;
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} /* if (changing subsegments) */
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} /* subseg_new() */
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/*
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* Local Variables:
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* comment-column: 0
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* fill-column: 131
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* End:
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*/
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/* end of subsegs.c */
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