old-cross-binutils/gas/subsegs.h
K. Richard Pixley fecd2382e7 Initial revision
1991-04-04 18:19:53 +00:00

65 lines
2.5 KiB
C

/* subsegs.h -> subsegs.c
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. */
/*
* For every sub-segment the user mentions in the ASsembler program,
* we make one struct frchain. Each sub-segment has exactly one struct frchain
* and vice versa.
*
* Struct frchain's are forward chained (in ascending order of sub-segment
* code number). The chain runs through frch_next of each subsegment.
* This makes it hard to find a subsegment's frags
* if programmer uses a lot of them. Most programs only use text0 and
* data0, so they don't suffer. At least this way:
* (1) There are no "arbitrary" restrictions on how many subsegments
* can be programmed;
* (2) Subsegments' frchain-s are (later) chained together in the order in
* which they are emitted for object file viz text then data.
*
* From each struct frchain dangles a chain of struct frags. The frags
* represent code fragments, for that sub-segment, forward chained.
*/
struct frchain /* control building of a frag chain */
{ /* FRCH = FRagment CHain control */
struct frag * frch_root; /* 1st struct frag in chain, or NULL */
struct frag * frch_last; /* last struct frag in chain, or NULL */
struct frchain * frch_next; /* next in chain of struct frchain-s */
segT frch_seg; /* SEG_TEXT or SEG_DATA. */
subsegT frch_subseg; /* subsegment number of this chain */
};
typedef struct frchain frchainS;
extern frchainS * frchain_root; /* NULL means no frchains yet. */
/* all subsegments' chains hang off here */
extern frchainS * frchain_now;
/* Frchain we are assembling into now */
/* That is, the current segment's frag */
/* chain, even if it contains no (complete) */
/* frags. */
extern frchainS * data0_frchainP;
/* Sentinel for frchain crawling. */
/* Points to the 1st data-segment frchain. */
/* (Which is pointed to by the last text- */
/* segment frchain.) */
/* end: subsegs.h */