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)
76 oldc = frchain_now->frch_obstack.chunk_size;
77 frchain_now->frch_obstack.chunk_size = 2 * nchars;
78 while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars
85 frchain_now->frch_obstack.chunk_size = oldc;
87 if (obstack_room (&frchain_now->frch_obstack) < 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
109 frag_new (old_frags_var_max_size)
110 /* Number of chars (already allocated on obstack frags) in
111 variable_length part of frag. */
112 int old_frags_var_max_size;
114 fragS *former_last_fragP;
117 assert (frchain_now->frch_last == frag_now);
119 /* Fix up old frag's fr_fix. */
120 frag_now->fr_fix = frag_now_fix () - old_frags_var_max_size;
121 /* Make sure its type is valid. */
122 assert (frag_now->fr_type != 0);
124 /* This will align the obstack so the next struct we allocate on it
125 will begin at a correct boundary. */
126 obstack_finish (&frchain_now->frch_obstack);
129 former_last_fragP = frchP->frch_last;
130 assert (former_last_fragP != 0);
131 assert (former_last_fragP == frag_now);
132 frag_now = frag_alloc (&frchP->frch_obstack);
134 as_where (&frag_now->fr_file, &frag_now->fr_line);
136 /* Generally, frag_now->points to an address rounded up to next
137 alignment. However, characters will add to obstack frags
138 IMMEDIATELY after the struct frag, even if they are not starting
139 at an alignment address. */
140 former_last_fragP->fr_next = frag_now;
141 frchP->frch_last = frag_now;
145 extern struct list_info_struct *listing_tail;
146 frag_now->line = listing_tail;
150 assert (frchain_now->frch_last == frag_now);
152 frag_now->fr_next = NULL;
158 * Start a new frag unless we have n more chars of room in the current frag.
159 * Close off the old frag with a .fill 0.
161 * Return the address of the 1st char to write into. Advance
162 * frag_now_growth past the new chars.
169 register char *retval;
171 if (now_seg == absolute_section)
173 as_bad ("attempt to allocate data in absolute section");
174 subseg_set (text_section, 0);
177 if (mri_common_symbol != NULL)
179 as_bad ("attempt to allocate data in common section");
180 mri_common_symbol = NULL;
184 retval = obstack_next_free (&frchain_now->frch_obstack);
185 obstack_blank_fast (&frchain_now->frch_obstack, nchars);
192 * Start a new frag unless we have max_chars more chars of room in the current frag.
193 * Close off the old frag with a .fill 0.
195 * Set up a machine_dependent relaxable frag, then start a new frag.
196 * Return the address of the 1st char of the var part of the old frag
201 frag_var (type, max_chars, var, subtype, symbol, offset, opcode)
205 relax_substateT subtype;
210 register char *retval;
212 frag_grow (max_chars);
213 retval = obstack_next_free (&frchain_now->frch_obstack);
214 obstack_blank_fast (&frchain_now->frch_obstack, max_chars);
215 frag_now->fr_var = var;
216 frag_now->fr_type = type;
217 frag_now->fr_subtype = subtype;
218 frag_now->fr_symbol = symbol;
219 frag_now->fr_offset = offset;
220 frag_now->fr_opcode = opcode;
222 TC_FRAG_INIT (frag_now);
224 as_where (&frag_now->fr_file, &frag_now->fr_line);
225 frag_new (max_chars);
232 * OVE: This variant of frag_var assumes that space for the tail has been
233 * allocated by caller.
234 * No call to frag_grow is done.
238 frag_variant (type, max_chars, var, subtype, symbol, offset, opcode)
242 relax_substateT subtype;
247 register char *retval;
249 retval = obstack_next_free (&frchain_now->frch_obstack);
250 frag_now->fr_var = var;
251 frag_now->fr_type = type;
252 frag_now->fr_subtype = subtype;
253 frag_now->fr_symbol = symbol;
254 frag_now->fr_offset = offset;
255 frag_now->fr_opcode = opcode;
257 TC_FRAG_INIT (frag_now);
259 as_where (&frag_now->fr_file, &frag_now->fr_line);
260 frag_new (max_chars);
262 } /* frag_variant() */
267 * Reduce the variable end of a frag to a harmless state.
271 register fragS *fragP;
273 fragP->fr_type = rs_fill;
274 fragP->fr_offset = 0;
278 /* Make an alignment frag. The size of this frag will be adjusted to
279 force the next frag to have the appropriate alignment. ALIGNMENT
280 is the power of two to which to align. FILL_CHARACTER is the
281 character to use to fill in any bytes which are skipped. MAX is
282 the maximum number of characters to skip when doing the alignment,
283 or 0 if there is no maximum. */
286 frag_align (alignment, fill_character, max)
291 if (now_seg == absolute_section)
295 new_off = ((abs_section_offset + alignment - 1)
296 &~ ((1 << alignment) - 1));
297 if (max == 0 || new_off - abs_section_offset <= (addressT) max)
298 abs_section_offset = new_off;
304 p = frag_var (rs_align, 1, 1, (relax_substateT) max,
305 (symbolS *) 0, (offsetT) alignment, (char *) 0);
310 /* Make an alignment frag like frag_align, but fill with a repeating
311 pattern rather than a single byte. ALIGNMENT is the power of two
312 to which to align. FILL_PATTERN is the fill pattern to repeat in
313 the bytes which are skipped. N_FILL is the number of bytes in
314 FILL_PATTERN. MAX is the maximum number of characters to skip when
315 doing the alignment, or 0 if there is no maximum. */
318 frag_align_pattern (alignment, fill_pattern, n_fill, max)
320 const char *fill_pattern;
326 p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max,
327 (symbolS *) 0, (offsetT) alignment, (char *) 0);
328 memcpy (p, fill_pattern, n_fill);
334 if (now_seg == absolute_section)
335 return abs_section_offset;
336 return (addressT) ((char*) obstack_next_free (&frchain_now->frch_obstack)
337 - frag_now->fr_literal);
341 frag_append_1_char (datum)
344 if (obstack_room (&frchain_now->frch_obstack) <= 1)
346 frag_wane (frag_now);
349 obstack_1grow (&frchain_now->frch_obstack, datum);