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/* frags.h - Header file for the frag concept.
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. */
#import "relax.h"
#import "struc-symbol.h"
/*
* A code fragment (frag) is some known number of chars, followed by some
* unknown number of chars. Typically the unknown number of chars is an
* instruction address whose size is yet unknown. We always know the greatest
* possible size the unknown number of chars may become, and reserve that
* much room at the end of the frag.
* Once created, frags do not change address during assembly.
* We chain the frags in (a) forward-linked list(s). The object-file address
* of the 1st char of a frag is generally not known until after relax().
* Many things at assembly time describe an address by {object-file-address
* of a particular frag}+offset.
BUG: it may be smarter to have a single pointer off to various different
notes for different frag kinds. See how code pans out.
*/
struct frag /* a code fragment */
{
unsigned long fr_address; /* Object file address. */
struct frag *fr_next; /* Chain forward; ascending address order. */
/* Rooted in frch_root. */
long fr_fix; /* (Fixed) number of chars we know we have. */
/* May be 0. */
long fr_var; /* (Variable) number of chars after above. */
/* May be 0. */
struct symbol *fr_symbol; /* For variable-length tail. */
long fr_offset; /* For variable-length tail. */
char *fr_opcode; /* ->opcode low addr byte,for relax()ation*/
relax_stateT fr_type; /* What state is my tail in? */
relax_substateT fr_subtype; /* Used to index in to md_relax_table for */
/* fr_type == rs_machine_dependent frags. */
char fr_literal[1]; /* Chars begin here. */
/* One day we will compile fr_literal[0]. */
};
typedef struct frag fragS;
/* We want to say fr_literal[0] below */
#define SIZEOF_STRUCT_FRAG \
((int)zero_address_frag.fr_literal - (int)&zero_address_frag)
/*
* frag_now points at the current frag we are building. This frag is incomplete.
* It is, however, included in frchain_now. Frag_now->fr_fix is not the total
* bytes in use for the frag. For that use:
* frag_now->fr_fix + obstack_next_free(&frags) - frag_now->fr_literal.
*/
extern fragS *frag_now;
/*
* Frags ONLY live in this obstack. We use obstack_next_free() macro
* so please don't put any other objects on this stack!
*/
extern struct obstack frags;
/* For foreign-segment symbol fixups. */
extern fragS zero_address_frag;
extern void frag_new(
int old_frags_var_max_size);
extern char * frag_more(
int nchars);
extern char *frag_var(
relax_stateT type,
int max_chars,
int var,
relax_substateT subtype,
symbolS *symbol,
long offset,
char *opcode);
extern void frag_wane(
fragS *fragP);
extern void frag_align(
int alignment,
int fill_character);
/*
* A macro to speed up appending exactly 1 char
* to current frag.
*/
/* JF changed < 1 to <= 1 to avoid a race conditon */
#define FRAG_APPEND_1_CHAR(datum) \
{ \
if (obstack_room( &frags ) <= 1) {\
frag_wane (frag_now); \
frag_new (0); \
} \
obstack_1grow( &frags, datum ); \
}
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