1 /* frags.c - manage frags -
2 Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 97, 1998
3 Free Software Foundation, Inc.
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
26 extern fragS zero_address_frag
;
27 extern fragS bss_address_frag
;
29 /* Initialization for frag routines. */
33 zero_address_frag
.fr_type
= rs_fill
;
34 bss_address_frag
.fr_type
= rs_fill
;
37 /* Allocate a frag on the specified obstack.
38 Call this routine from everywhere else, so that all the weird alignment
39 hackery can be done in just one place. */
47 (void) obstack_alloc (ob
, 0);
48 oalign
= obstack_alignment_mask (ob
);
49 obstack_alignment_mask (ob
) = 0;
50 ptr
= (fragS
*) obstack_alloc (ob
, SIZEOF_STRUCT_FRAG
);
51 obstack_alignment_mask (ob
) = oalign
;
52 memset (ptr
, 0, SIZEOF_STRUCT_FRAG
);
59 * Try to augment current frag by nchars chars.
60 * If there is no room, close of the current frag with a ".fill 0"
61 * and begin a new frag. Unless the new frag has nchars chars available
62 * do not return. Do not set up any fields of *now_frag.
68 if (obstack_room (&frchain_now
->frch_obstack
) < nchars
)
75 oldc
= frchain_now
->frch_obstack
.chunk_size
;
76 frchain_now
->frch_obstack
.chunk_size
= 2 * nchars
+ SIZEOF_STRUCT_FRAG
;
77 while ((n
= obstack_room (&frchain_now
->frch_obstack
)) < nchars
)
82 frchain_now
->frch_obstack
.chunk_size
= oldc
;
84 if (obstack_room (&frchain_now
->frch_obstack
) < nchars
)
85 as_fatal (_("Can't extend frag %d. chars"), nchars
);
91 * Call this to close off a completed frag, and start up a new (empty)
92 * frag, in the same subsegment as the old frag.
93 * [frchain_now remains the same but frag_now is updated.]
94 * Because this calculates the correct value of fr_fix by
95 * looking at the obstack 'frags', it needs to know how many
96 * characters at the end of the old frag belong to (the maximal)
97 * fr_var: the rest must belong to fr_fix.
98 * It doesn't actually set up the old frag's fr_var: you may have
99 * set fr_var == 1, but allocated 10 chars to the end of the frag:
100 * in this case you pass old_frags_var_max_size == 10.
102 * Make a new frag, initialising some components. Link new frag at end
106 frag_new (old_frags_var_max_size
)
107 /* Number of chars (already allocated on obstack frags) in
108 variable_length part of frag. */
109 int old_frags_var_max_size
;
111 fragS
*former_last_fragP
;
114 assert (frchain_now
->frch_last
== frag_now
);
116 /* Fix up old frag's fr_fix. */
117 frag_now
->fr_fix
= frag_now_fix () - old_frags_var_max_size
;
118 /* Make sure its type is valid. */
119 assert (frag_now
->fr_type
!= 0);
121 /* This will align the obstack so the next struct we allocate on it
122 will begin at a correct boundary. */
123 obstack_finish (&frchain_now
->frch_obstack
);
126 former_last_fragP
= frchP
->frch_last
;
127 assert (former_last_fragP
!= 0);
128 assert (former_last_fragP
== frag_now
);
129 frag_now
= frag_alloc (&frchP
->frch_obstack
);
131 as_where (&frag_now
->fr_file
, &frag_now
->fr_line
);
133 /* Generally, frag_now->points to an address rounded up to next
134 alignment. However, characters will add to obstack frags
135 IMMEDIATELY after the struct frag, even if they are not starting
136 at an alignment address. */
137 former_last_fragP
->fr_next
= frag_now
;
138 frchP
->frch_last
= frag_now
;
142 extern struct list_info_struct
*listing_tail
;
143 frag_now
->line
= listing_tail
;
147 assert (frchain_now
->frch_last
== frag_now
);
149 frag_now
->fr_next
= NULL
;
155 * Start a new frag unless we have n more chars of room in the current frag.
156 * Close off the old frag with a .fill 0.
158 * Return the address of the 1st char to write into. Advance
159 * frag_now_growth past the new chars.
166 register char *retval
;
168 if (now_seg
== absolute_section
)
170 as_bad (_("attempt to allocate data in absolute section"));
171 subseg_set (text_section
, 0);
174 if (mri_common_symbol
!= NULL
)
176 as_bad (_("attempt to allocate data in common section"));
177 mri_common_symbol
= NULL
;
181 retval
= obstack_next_free (&frchain_now
->frch_obstack
);
182 obstack_blank_fast (&frchain_now
->frch_obstack
, nchars
);
189 * Start a new frag unless we have max_chars more chars of room in the current frag.
190 * Close off the old frag with a .fill 0.
192 * Set up a machine_dependent relaxable frag, then start a new frag.
193 * Return the address of the 1st char of the var part of the old frag
198 frag_var (type
, max_chars
, var
, subtype
, symbol
, offset
, opcode
)
202 relax_substateT subtype
;
207 register char *retval
;
209 frag_grow (max_chars
);
210 retval
= obstack_next_free (&frchain_now
->frch_obstack
);
211 obstack_blank_fast (&frchain_now
->frch_obstack
, max_chars
);
212 frag_now
->fr_var
= var
;
213 frag_now
->fr_type
= type
;
214 frag_now
->fr_subtype
= subtype
;
215 frag_now
->fr_symbol
= symbol
;
216 frag_now
->fr_offset
= offset
;
217 frag_now
->fr_opcode
= opcode
;
219 frag_now
->fr_cgen
.insn
= 0;
220 frag_now
->fr_cgen
.opindex
= 0;
221 frag_now
->fr_cgen
.opinfo
= 0;
224 TC_FRAG_INIT (frag_now
);
226 as_where (&frag_now
->fr_file
, &frag_now
->fr_line
);
227 frag_new (max_chars
);
234 * OVE: This variant of frag_var assumes that space for the tail has been
235 * allocated by caller.
236 * No call to frag_grow is done.
240 frag_variant (type
, max_chars
, var
, subtype
, symbol
, offset
, opcode
)
244 relax_substateT subtype
;
249 register char *retval
;
251 retval
= obstack_next_free (&frchain_now
->frch_obstack
);
252 frag_now
->fr_var
= var
;
253 frag_now
->fr_type
= type
;
254 frag_now
->fr_subtype
= subtype
;
255 frag_now
->fr_symbol
= symbol
;
256 frag_now
->fr_offset
= offset
;
257 frag_now
->fr_opcode
= opcode
;
259 frag_now
->fr_cgen
.insn
= 0;
260 frag_now
->fr_cgen
.opindex
= 0;
261 frag_now
->fr_cgen
.opinfo
= 0;
264 TC_FRAG_INIT (frag_now
);
266 as_where (&frag_now
->fr_file
, &frag_now
->fr_line
);
267 frag_new (max_chars
);
269 } /* frag_variant() */
274 * Reduce the variable end of a frag to a harmless state.
278 register fragS
*fragP
;
280 fragP
->fr_type
= rs_fill
;
281 fragP
->fr_offset
= 0;
285 /* Make an alignment frag. The size of this frag will be adjusted to
286 force the next frag to have the appropriate alignment. ALIGNMENT
287 is the power of two to which to align. FILL_CHARACTER is the
288 character to use to fill in any bytes which are skipped. MAX is
289 the maximum number of characters to skip when doing the alignment,
290 or 0 if there is no maximum. */
293 frag_align (alignment
, fill_character
, max
)
298 if (now_seg
== absolute_section
)
302 new_off
= ((abs_section_offset
+ alignment
- 1)
303 &~ ((1 << alignment
) - 1));
304 if (max
== 0 || new_off
- abs_section_offset
<= (addressT
) max
)
305 abs_section_offset
= new_off
;
311 p
= frag_var (rs_align
, 1, 1, (relax_substateT
) max
,
312 (symbolS
*) 0, (offsetT
) alignment
, (char *) 0);
317 /* Make an alignment frag like frag_align, but fill with a repeating
318 pattern rather than a single byte. ALIGNMENT is the power of two
319 to which to align. FILL_PATTERN is the fill pattern to repeat in
320 the bytes which are skipped. N_FILL is the number of bytes in
321 FILL_PATTERN. MAX is the maximum number of characters to skip when
322 doing the alignment, or 0 if there is no maximum. */
325 frag_align_pattern (alignment
, fill_pattern
, n_fill
, max
)
327 const char *fill_pattern
;
333 p
= frag_var (rs_align
, n_fill
, n_fill
, (relax_substateT
) max
,
334 (symbolS
*) 0, (offsetT
) alignment
, (char *) 0);
335 memcpy (p
, fill_pattern
, n_fill
);
341 if (now_seg
== absolute_section
)
342 return abs_section_offset
;
343 return (addressT
) ((char*) obstack_next_free (&frchain_now
->frch_obstack
)
344 - frag_now
->fr_literal
);
348 frag_append_1_char (datum
)
351 if (obstack_room (&frchain_now
->frch_obstack
) <= 1)
353 frag_wane (frag_now
);
356 obstack_1grow (&frchain_now
->frch_obstack
, datum
);
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