1 /* frags.c - manage frags -
2 Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc.
4 This file is part of GAS, the GNU Assembler.
6 GAS is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 1, or (at your option)
11 GAS is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GAS; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
20 /* static const char rcsid[] = "$Id$"; */
26 struct obstack frags
; /* All, and only, frags live here. */
28 fragS zero_address_frag
= {
36 rs_fill
, /* fr_type */
38 0, /* fr_pcrel_adjust */
40 0 /* fr_literal [0] */
43 fragS bss_address_frag
= {
44 0, /* fr_address. Gets filled in to make up
52 rs_fill
, /* fr_type */
54 0, /* fr_pcrel_adjust */
56 0 /* fr_literal [0] */
63 * Try to augment current frag by nchars chars.
64 * If there is no room, close of the current frag with a ".fill 0"
65 * and begin a new frag. Unless the new frag has nchars chars available
66 * do not return. Do not set up any fields of *now_frag.
68 static void frag_grow(nchars
)
71 if (obstack_room (&frags
) < nchars
) {
78 oldc
=frags
.chunk_size
;
79 frags
.chunk_size
=2*nchars
;
80 while((n
=obstack_room(&frags
))<nchars
&& n
<oldn
) {
85 frags
.chunk_size
=oldc
;
87 if (obstack_room (&frags
) < nchars
)
88 as_fatal("Can't extend frag %d. chars", nchars
);
94 * Call this to close off a completed frag, and start up a new (empty)
95 * frag, in the same subsegment as the old frag.
96 * [frchain_now remains the same but frag_now is updated.]
97 * Because this calculates the correct value of fr_fix by
98 * looking at the obstack 'frags', it needs to know how many
99 * characters at the end of the old frag belong to (the maximal)
100 * fr_var: the rest must belong to fr_fix.
101 * It doesn't actually set up the old frag's fr_var: you may have
102 * set fr_var == 1, but allocated 10 chars to the end of the frag:
103 * in this case you pass old_frags_var_max_size == 10.
105 * Make a new frag, initialising some components. Link new frag at end
108 void frag_new(old_frags_var_max_size
)
109 int old_frags_var_max_size
; /* Number of chars (already allocated on
111 /* in variable_length part of frag. */
113 register fragS
* former_last_fragP
;
114 /* char *throw_away_pointer; JF unused */
115 register frchainS
* frchP
;
118 frag_now
->fr_fix
= (char *) (obstack_next_free (&frags
)) -
119 (frag_now
->fr_literal
) - old_frags_var_max_size
;
120 /* Fix up old frag's fr_fix. */
122 obstack_finish (&frags
);
123 /* This will align the obstack so the */
124 /* next struct we allocate on it will */
125 /* begin at a correct boundary. */
128 former_last_fragP
= frchP
->frch_last
;
129 know (former_last_fragP
);
130 know (former_last_fragP
== frag_now
);
131 obstack_blank (&frags
, SIZEOF_STRUCT_FRAG
);
132 /* We expect this will begin at a correct */
133 /* boundary for a struct. */
134 tmp
=obstack_alignment_mask(&frags
);
135 obstack_alignment_mask(&frags
)=0; /* Turn off alignment */
136 /* If we ever hit a machine
137 where strings must be
138 aligned, we Lose Big */
139 frag_now
=(fragS
*)obstack_finish(&frags
);
140 obstack_alignment_mask(&frags
)=tmp
; /* Restore alignment */
142 /* Just in case we don't get zero'd bytes */
143 bzero(frag_now
, SIZEOF_STRUCT_FRAG
);
145 /* obstack_unaligned_done (&frags, &frag_now); */
146 /* know (frags.obstack_c_next_free == frag_now->fr_literal); */
147 /* Generally, frag_now->points to an */
148 /* address rounded up to next alignment. */
149 /* However, characters will add to obstack */
150 /* frags IMMEDIATELY after the struct frag, */
151 /* even if they are not starting at an */
152 /* alignment address. */
153 former_last_fragP
->fr_next
= frag_now
;
154 frchP
->frch_last
= frag_now
;
155 frag_now
->fr_next
= NULL
;
161 * Start a new frag unless we have n more chars of room in the current frag.
162 * Close off the old frag with a .fill 0.
164 * Return the address of the 1st char to write into. Advance
165 * frag_now_growth past the new chars.
168 char *frag_more (nchars
)
171 register char *retval
;
174 retval
= obstack_next_free (&frags
);
175 obstack_blank_fast (&frags
, nchars
);
182 * Start a new frag unless we have max_chars more chars of room in the current frag.
183 * Close off the old frag with a .fill 0.
185 * Set up a machine_dependent relaxable frag, then start a new frag.
186 * Return the address of the 1st char of the var part of the old frag
190 char *frag_var(type
, max_chars
, var
, subtype
, symbol
, offset
, opcode
)
194 relax_substateT subtype
;
199 register char *retval
;
201 frag_grow (max_chars
);
202 retval
= obstack_next_free (&frags
);
203 obstack_blank_fast (&frags
, max_chars
);
204 frag_now
->fr_var
= var
;
205 frag_now
->fr_type
= type
;
206 frag_now
->fr_subtype
= subtype
;
207 frag_now
->fr_symbol
= symbol
;
208 frag_now
->fr_offset
= offset
;
209 frag_now
->fr_opcode
= opcode
;
210 /* default these to zero. */
211 frag_now
->fr_pcrel_adjust
= 0;
212 frag_now
->fr_bsr
= 0;
213 frag_new (max_chars
);
220 * OVE: This variant of frag_var assumes that space for the tail has been
221 * allocated by caller.
222 * No call to frag_grow is done.
223 * Two new arguments have been added.
226 char *frag_variant(type
, max_chars
, var
, subtype
, symbol
, offset
, opcode
, pcrel_adjust
,bsr
)
230 relax_substateT subtype
;
237 register char *retval
;
239 /* frag_grow (max_chars); */
240 retval
= obstack_next_free (&frags
);
241 /* obstack_blank_fast (&frags, max_chars); */ /* OVE: so far the only diff */
242 frag_now
->fr_var
= var
;
243 frag_now
->fr_type
= type
;
244 frag_now
->fr_subtype
= subtype
;
245 frag_now
->fr_symbol
= symbol
;
246 frag_now
->fr_offset
= offset
;
247 frag_now
->fr_opcode
= opcode
;
248 frag_now
->fr_pcrel_adjust
= pcrel_adjust
;
249 frag_now
->fr_bsr
= bsr
;
250 frag_new (max_chars
);
252 } /* frag_variant() */
257 * Reduce the variable end of a frag to a harmless state.
259 void frag_wane(fragP
)
260 register fragS
* fragP
;
262 fragP
->fr_type
= rs_fill
;
263 fragP
->fr_offset
= 0;
270 * Make a frag for ".align foo,bar". Call is "frag_align (foo,bar);".
271 * Foo & bar are absolute integers.
273 * Call to close off the current frag with a ".align", then start a new
274 * (so far empty) frag, in the same subsegment as the last frag.
277 void frag_align(alignment
, fill_character
)
281 *(frag_var (rs_align
, 1, 1, (relax_substateT
)0, (symbolS
*)0,
282 (long)alignment
, (char *)0)) = fill_character
;
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