2003-07-14 Christian Groessler <chris@groessler.org>
[deliverable/binutils-gdb.git] / gas / frags.c
CommitLineData
252b5132 1/* frags.c - manage frags -
f7e42eb4
NC
2 Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000
252b5132
RH
4 Free Software Foundation, Inc.
5
6 This file is part of GAS, the GNU Assembler.
7
8 GAS is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
11 any later version.
12
13 GAS is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with GAS; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
21 02111-1307, USA. */
22
23#include "as.h"
24#include "subsegs.h"
25#include "obstack.h"
26
27extern fragS zero_address_frag;
28extern fragS bss_address_frag;
29\f
30/* Initialization for frag routines. */
29f8404c 31
252b5132
RH
32void
33frag_init ()
34{
35 zero_address_frag.fr_type = rs_fill;
36 bss_address_frag.fr_type = rs_fill;
37}
38\f
39/* Allocate a frag on the specified obstack.
40 Call this routine from everywhere else, so that all the weird alignment
41 hackery can be done in just one place. */
29f8404c 42
252b5132
RH
43fragS *
44frag_alloc (ob)
45 struct obstack *ob;
46{
47 fragS *ptr;
48 int oalign;
49
50 (void) obstack_alloc (ob, 0);
51 oalign = obstack_alignment_mask (ob);
52 obstack_alignment_mask (ob) = 0;
53 ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG);
54 obstack_alignment_mask (ob) = oalign;
55 memset (ptr, 0, SIZEOF_STRUCT_FRAG);
56 return ptr;
57}
58\f
29f8404c
KH
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. */
63
64void
252b5132
RH
65frag_grow (nchars)
66 unsigned int nchars;
67{
68 if (obstack_room (&frchain_now->frch_obstack) < nchars)
69 {
70 unsigned int n;
71 long oldc;
72
73 frag_wane (frag_now);
74 frag_new (0);
75 oldc = frchain_now->frch_obstack.chunk_size;
76 frchain_now->frch_obstack.chunk_size = 2 * nchars + SIZEOF_STRUCT_FRAG;
3f9b03b5
AM
77 if (frchain_now->frch_obstack.chunk_size > 0)
78 while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars
79 && (unsigned long) frchain_now->frch_obstack.chunk_size > nchars)
80 {
81 frag_wane (frag_now);
82 frag_new (0);
83 }
252b5132
RH
84 frchain_now->frch_obstack.chunk_size = oldc;
85 }
86 if (obstack_room (&frchain_now->frch_obstack) < nchars)
0e389e77 87 as_fatal (_("can't extend frag %u chars"), nchars);
252b5132
RH
88}
89\f
29f8404c
KH
90/* Call this to close off a completed frag, and start up a new (empty)
91 frag, in the same subsegment as the old frag.
92 [frchain_now remains the same but frag_now is updated.]
93 Because this calculates the correct value of fr_fix by
94 looking at the obstack 'frags', it needs to know how many
95 characters at the end of the old frag belong to the maximal
96 variable part; The rest must belong to fr_fix.
97 It doesn't actually set up the old frag's fr_var. You may have
98 set fr_var == 1, but allocated 10 chars to the end of the frag;
99 In this case you pass old_frags_var_max_size == 10.
100 In fact, you may use fr_var for something totally unrelated to the
101 size of the variable part of the frag; None of the generic frag
102 handling code makes use of fr_var.
103
104 Make a new frag, initialising some components. Link new frag at end
105 of frchain_now. */
106
107void
252b5132
RH
108frag_new (old_frags_var_max_size)
109 /* Number of chars (already allocated on obstack frags) in
29f8404c 110 variable_length part of frag. */
252b5132
RH
111 int old_frags_var_max_size;
112{
113 fragS *former_last_fragP;
114 frchainS *frchP;
115
116 assert (frchain_now->frch_last == frag_now);
117
118 /* Fix up old frag's fr_fix. */
bea9907b 119 frag_now->fr_fix = frag_now_fix_octets () - old_frags_var_max_size;
252b5132
RH
120 /* Make sure its type is valid. */
121 assert (frag_now->fr_type != 0);
122
123 /* This will align the obstack so the next struct we allocate on it
29f8404c 124 will begin at a correct boundary. */
252b5132
RH
125 obstack_finish (&frchain_now->frch_obstack);
126 frchP = frchain_now;
127 know (frchP);
128 former_last_fragP = frchP->frch_last;
129 assert (former_last_fragP != 0);
130 assert (former_last_fragP == frag_now);
131 frag_now = frag_alloc (&frchP->frch_obstack);
132
133 as_where (&frag_now->fr_file, &frag_now->fr_line);
134
135 /* Generally, frag_now->points to an address rounded up to next
136 alignment. However, characters will add to obstack frags
137 IMMEDIATELY after the struct frag, even if they are not starting
29f8404c 138 at an alignment address. */
252b5132
RH
139 former_last_fragP->fr_next = frag_now;
140 frchP->frch_last = frag_now;
141
142#ifndef NO_LISTING
143 {
144 extern struct list_info_struct *listing_tail;
145 frag_now->line = listing_tail;
146 }
147#endif
148
149 assert (frchain_now->frch_last == frag_now);
150
151 frag_now->fr_next = NULL;
29f8404c 152}
252b5132 153\f
29f8404c
KH
154/* Start a new frag unless we have n more chars of room in the current frag.
155 Close off the old frag with a .fill 0.
156
157 Return the address of the 1st char to write into. Advance
158 frag_now_growth past the new chars. */
252b5132
RH
159
160char *
161frag_more (nchars)
162 int nchars;
163{
164 register char *retval;
165
166 if (now_seg == absolute_section)
167 {
168 as_bad (_("attempt to allocate data in absolute section"));
169 subseg_set (text_section, 0);
170 }
171
172 if (mri_common_symbol != NULL)
173 {
174 as_bad (_("attempt to allocate data in common section"));
175 mri_common_symbol = NULL;
176 }
177
178 frag_grow (nchars);
179 retval = obstack_next_free (&frchain_now->frch_obstack);
180 obstack_blank_fast (&frchain_now->frch_obstack, nchars);
181 return (retval);
29f8404c 182}
252b5132 183\f
29f8404c
KH
184/* Start a new frag unless we have max_chars more chars of room in the
185 current frag. Close off the old frag with a .fill 0.
186
187 Set up a machine_dependent relaxable frag, then start a new frag.
188 Return the address of the 1st char of the var part of the old frag
189 to write into. */
252b5132
RH
190
191char *
192frag_var (type, max_chars, var, subtype, symbol, offset, opcode)
193 relax_stateT type;
194 int max_chars;
195 int var;
196 relax_substateT subtype;
197 symbolS *symbol;
198 offsetT offset;
199 char *opcode;
200{
201 register char *retval;
202
203 frag_grow (max_chars);
204 retval = obstack_next_free (&frchain_now->frch_obstack);
205 obstack_blank_fast (&frchain_now->frch_obstack, max_chars);
206 frag_now->fr_var = var;
207 frag_now->fr_type = type;
208 frag_now->fr_subtype = subtype;
209 frag_now->fr_symbol = symbol;
210 frag_now->fr_offset = offset;
211 frag_now->fr_opcode = opcode;
212#ifdef USING_CGEN
213 frag_now->fr_cgen.insn = 0;
214 frag_now->fr_cgen.opindex = 0;
215 frag_now->fr_cgen.opinfo = 0;
216#endif
217#ifdef TC_FRAG_INIT
218 TC_FRAG_INIT (frag_now);
219#endif
220 as_where (&frag_now->fr_file, &frag_now->fr_line);
221 frag_new (max_chars);
222 return (retval);
223}
224\f
29f8404c
KH
225/* OVE: This variant of frag_var assumes that space for the tail has been
226 allocated by caller.
227 No call to frag_grow is done. */
252b5132
RH
228
229char *
230frag_variant (type, max_chars, var, subtype, symbol, offset, opcode)
231 relax_stateT type;
232 int max_chars;
233 int var;
234 relax_substateT subtype;
235 symbolS *symbol;
236 offsetT offset;
237 char *opcode;
238{
239 register char *retval;
240
241 retval = obstack_next_free (&frchain_now->frch_obstack);
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#ifdef USING_CGEN
249 frag_now->fr_cgen.insn = 0;
250 frag_now->fr_cgen.opindex = 0;
251 frag_now->fr_cgen.opinfo = 0;
252#endif
253#ifdef TC_FRAG_INIT
254 TC_FRAG_INIT (frag_now);
255#endif
256 as_where (&frag_now->fr_file, &frag_now->fr_line);
257 frag_new (max_chars);
258 return (retval);
29f8404c 259}
252b5132 260\f
29f8404c
KH
261/* Reduce the variable end of a frag to a harmless state. */
262
263void
252b5132
RH
264frag_wane (fragP)
265 register fragS *fragP;
266{
267 fragP->fr_type = rs_fill;
268 fragP->fr_offset = 0;
269 fragP->fr_var = 0;
270}
271\f
272/* Make an alignment frag. The size of this frag will be adjusted to
273 force the next frag to have the appropriate alignment. ALIGNMENT
274 is the power of two to which to align. FILL_CHARACTER is the
275 character to use to fill in any bytes which are skipped. MAX is
276 the maximum number of characters to skip when doing the alignment,
277 or 0 if there is no maximum. */
278
29f8404c 279void
252b5132
RH
280frag_align (alignment, fill_character, max)
281 int alignment;
282 int fill_character;
283 int max;
284{
285 if (now_seg == absolute_section)
286 {
287 addressT new_off;
65e68b04 288 addressT mask;
252b5132 289
29f8404c
KH
290 mask = (~(addressT) 0) << alignment;
291 new_off = (abs_section_offset + ~mask) & mask;
252b5132
RH
292 if (max == 0 || new_off - abs_section_offset <= (addressT) max)
293 abs_section_offset = new_off;
294 }
295 else
296 {
297 char *p;
298
299 p = frag_var (rs_align, 1, 1, (relax_substateT) max,
300 (symbolS *) 0, (offsetT) alignment, (char *) 0);
301 *p = fill_character;
302 }
303}
304
305/* Make an alignment frag like frag_align, but fill with a repeating
306 pattern rather than a single byte. ALIGNMENT is the power of two
307 to which to align. FILL_PATTERN is the fill pattern to repeat in
308 the bytes which are skipped. N_FILL is the number of bytes in
309 FILL_PATTERN. MAX is the maximum number of characters to skip when
310 doing the alignment, or 0 if there is no maximum. */
311
29f8404c 312void
252b5132
RH
313frag_align_pattern (alignment, fill_pattern, n_fill, max)
314 int alignment;
315 const char *fill_pattern;
316 int n_fill;
317 int max;
318{
319 char *p;
320
321 p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max,
322 (symbolS *) 0, (offsetT) alignment, (char *) 0);
323 memcpy (p, fill_pattern, n_fill);
324}
325
0a9ef439
RH
326/* The NOP_OPCODE is for the alignment fill value. Fill it with a nop
327 instruction so that the disassembler does not choke on it. */
328#ifndef NOP_OPCODE
329#define NOP_OPCODE 0x00
330#endif
331
332/* Use this to restrict the amount of memory allocated for representing
333 the alignment code. Needs to be large enough to hold any fixed sized
334 prologue plus the replicating portion. */
335#ifndef MAX_MEM_FOR_RS_ALIGN_CODE
336 /* Assume that if HANDLE_ALIGN is not defined then no special action
337 is required to code fill, which means that we get just repeat the
338 one NOP_OPCODE byte. */
339# ifndef HANDLE_ALIGN
340# define MAX_MEM_FOR_RS_ALIGN_CODE 1
341# else
342# define MAX_MEM_FOR_RS_ALIGN_CODE ((1 << alignment) - 1)
343# endif
344#endif
345
346void
347frag_align_code (alignment, max)
348 int alignment;
349 int max;
350{
351 char *p;
352
353 p = frag_var (rs_align_code, MAX_MEM_FOR_RS_ALIGN_CODE, 1,
354 (relax_substateT) max, (symbolS *) 0,
355 (offsetT) alignment, (char *) 0);
356 *p = NOP_OPCODE;
357}
358
252b5132 359addressT
bea9907b 360frag_now_fix_octets ()
252b5132
RH
361{
362 if (now_seg == absolute_section)
363 return abs_section_offset;
bea9907b 364
29f8404c
KH
365 return ((char *) obstack_next_free (&frchain_now->frch_obstack)
366 - frag_now->fr_literal);
bea9907b
TW
367}
368
369addressT
370frag_now_fix ()
371{
29f8404c 372 return frag_now_fix_octets () / OCTETS_PER_BYTE;
252b5132
RH
373}
374
375void
376frag_append_1_char (datum)
377 int datum;
378{
379 if (obstack_room (&frchain_now->frch_obstack) <= 1)
380 {
381 frag_wane (frag_now);
382 frag_new (0);
383 }
384 obstack_1grow (&frchain_now->frch_obstack, datum);
385}
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