4.4BSD/usr/src/contrib/gas-1.38/subsegs.c
/* subsegs.c - subsegments -
Copyright (C) 1987 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 1, 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. */
/*
* Segments & sub-segments.
*/
#include "as.h"
#include "subsegs.h"
#include "obstack.h"
#include "frags.h"
#include "struc-symbol.h"
#include "write.h"
frchainS* frchain_root,
* frchain_now, /* Commented in "subsegs.h". */
* data0_frchainP;
const int /* in: segT out: N_TYPE bits */
seg_N_TYPE[] = {
N_ABS,
N_TEXT,
N_DATA,
N_BSS,
N_UNDF,
N_UNDF,
N_UNDF,
N_UNDF,
N_UNDF,
N_UNDF
};
char * const /* in: segT out: char* */
seg_name[] = {
"absolute",
"text",
"data",
"bss",
"unknown",
"absent",
"pass1",
"ASSEMBLER-INTERNAL-LOGIC-ERROR!",
"bignum/flonum",
"difference",
""
}; /* Used by error reporters, dumpers etc. */
const segT N_TYPE_seg [N_TYPE+2] = /* N_TYPE == 0x1E = 32-2 */
{
SEG_UNKNOWN, /* N_UNDF == 0 */
SEG_GOOF,
SEG_ABSOLUTE, /* N_ABS == 2 */
SEG_GOOF,
SEG_TEXT, /* N_TEXT == 4 */
SEG_GOOF,
SEG_DATA, /* N_DATA == 6 */
SEG_GOOF,
SEG_BSS, /* N_BSS == 8 */
SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF,
SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF,
SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF, SEG_GOOF
};
void
subsegs_begin()
{
/* Check table(s) seg_name[], seg_N_TYPE[] is in correct order */
know( SEG_ABSOLUTE ==0 );
know( SEG_TEXT ==1 );
know( SEG_DATA ==2 );
know( SEG_BSS ==3 );
know( SEG_UNKNOWN ==4 );
know( SEG_NONE ==5 );
know( SEG_PASS1 ==6 );
know( SEG_GOOF ==7 );
know( SEG_BIG ==8 );
know( SEG_DIFFERENCE ==9 );
know( SEG_MAXIMUM_ORDINAL == SEG_DIFFERENCE );
know( seg_name [(int) SEG_MAXIMUM_ORDINAL + 1] [0] == 0 );
obstack_begin( &frags, 5000);
frchain_root = NULL;
frchain_now = NULL; /* Warn new_subseg() that we are booting. */
/* Fake up 1st frag. */
/* It won't be used=> is ok if obstack... */
/* pads the end of it for alignment. */
frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
/* obstack_1blank( &frags, SIZEOF_STRUCT_FRAG, & frag_now ); */
/* This 1st frag will not be in any frchain. */
/* We simply give subseg_new somewhere to scribble. */
now_subseg = 42; /* Lie for 1st call to subseg_new. */
subseg_new (SEG_DATA, 0); /* .data 0 */
data0_frchainP = frchain_now;
}
/*
* subseg_change()
*
* Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
* subsegment. If we are already in the correct subsegment, change nothing.
* This is used eg as a worker for subseg_new [which does make a new frag_now]
* and for changing segments after we have read the source. We construct eg
* fixSs even after the source file is read, so we do have to keep the
* segment context correct.
*/
void
subseg_change (seg, subseg)
register segT seg;
register int subseg;
{
now_seg = seg;
now_subseg = subseg;
if (seg == SEG_DATA)
{
seg_fix_rootP = & data_fix_root;
}
else
{
know (seg == SEG_TEXT);
seg_fix_rootP = & text_fix_root;
}
}
/*
* subseg_new()
*
* If you attempt to change to the current subsegment, nothing happens.
*
* In: segT, subsegT code for new subsegment.
* frag_now -> incomplete frag for current subsegment.
* If frag_now==NULL, then there is no old, incomplete frag, so
* the old frag is not closed off.
*
* Out: now_subseg, now_seg updated.
* Frchain_now points to the (possibly new) struct frchain for this
* sub-segment.
* Frchain_root updated if needed.
*/
void
subseg_new (seg, subseg) /* begin assembly for a new sub-segment */
register segT seg; /* SEG_DATA or SEG_TEXT */
register subsegT subseg;
{
long tmp; /* JF for obstack alignment hacking */
know( seg == SEG_DATA || seg == SEG_TEXT );
if (seg != now_seg || subseg != now_subseg)
{ /* we just changed sub-segments */
register frchainS * frcP; /* crawl frchain chain */
register frchainS** lastPP; /* address of last pointer */
frchainS * newP; /* address of new frchain */
register fragS * former_last_fragP;
register fragS * new_fragP;
if (frag_now) /* If not bootstrapping. */
{
frag_now -> fr_fix = obstack_next_free(& frags) - frag_now -> fr_literal;
frag_wane(frag_now); /* Close off any frag in old subseg. */
}
/*
* It would be nice to keep an obstack for each subsegment, if we swap
* subsegments a lot. Hence we would have much fewer frag_wanes().
*/
{
obstack_finish( &frags);
/*
* If we don't do the above, the next object we put on obstack frags
* will appear to start at the fr_literal of the current frag.
* Also, above ensures that the next object will begin on a
* address that is aligned correctly for the engine that runs
* this program.
*/
}
subseg_change (seg, (int)subseg);
/*
* Attempt to find or make a frchain for that sub seg.
* Crawl along chain of frchainSs, begins @ frchain_root.
* If we need to make a frchainS, link it into correct
* position of chain rooted in frchain_root.
*/
for (frcP = * (lastPP = & frchain_root);
frcP
&& (int)(frcP -> frch_seg) <= (int)seg;
frcP = * ( lastPP = & frcP -> frch_next)
)
{
if ( (int)(frcP -> frch_seg) == (int)seg
&& frcP -> frch_subseg >= subseg)
{
break;
}
}
/*
* frcP: Address of the 1st frchainS in correct segment with
* frch_subseg >= subseg.
* We want to either use this frchainS, or we want
* to insert a new frchainS just before it.
*
* If frcP==NULL, then we are at the end of the chain
* of frchainS-s. A NULL frcP means we fell off the end
* of the chain looking for a
* frch_subseg >= subseg, so we
* must make a new frchainS.
*
* If we ever maintain a pointer to
* the last frchainS in the chain, we change that pointer
* ONLY when frcP==NULL.
*
* lastPP: Address of the pointer with value frcP;
* Never NULL.
* May point to frchain_root.
*
*/
if ( ! frcP
|| ( (int)(frcP -> frch_seg) > (int)seg
|| frcP->frch_subseg > subseg)) /* Kinky logic only works with 2 segments. */
{
/*
* This should be the only code that creates a frchainS.
*/
newP=(frchainS *)obstack_alloc(&frags,sizeof(frchainS));
/* obstack_1blank( &frags, sizeof(frchainS), &newP); */
/* This begines on a good boundary */
/* because a obstack_done() preceeded it. */
/* It implies an obstack_done(), so we */
/* expect the next object allocated to */
/* begin on a correct boundary. */
*lastPP = newP;
newP -> frch_next = frcP; /* perhaps NULL */
(frcP = newP) -> frch_subseg = subseg;
newP -> frch_seg = seg;
newP -> frch_last = NULL;
}
/*
* Here with frcP ->ing to the frchainS for subseg.
*/
frchain_now = frcP;
/*
* Make a fresh frag for the subsegment.
*/
/* We expect this to happen on a correct */
/* boundary since it was proceeded by a */
/* obstack_done(). */
tmp=obstack_alignment_mask(&frags); /* JF disable alignment */
obstack_alignment_mask(&frags)=0;
frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
obstack_alignment_mask(&frags)=tmp;
/* know( frags . obstack_c_next_free == frag_now -> fr_literal ); */
/* But we want any more chars to come */
/* immediately after the structure we just made. */
new_fragP = frag_now;
new_fragP -> fr_next = NULL;
/*
* Append new frag to current frchain.
*/
former_last_fragP = frcP -> frch_last;
if (former_last_fragP)
{
know( former_last_fragP -> fr_next == NULL );
know( frchain_now -> frch_root );
former_last_fragP -> fr_next = new_fragP;
}
else
{
frcP -> frch_root = new_fragP;
}
frcP -> frch_last = new_fragP;
} /* if (changing subsegments) */
} /* subseg_new() */
/* end: subsegs.c */