1 /* subsegs.c - subsegments -
2 Copyright (C) 1987, 1990, 1991, 1992 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 2, 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. */
21 * Segments & sub-segments.
25 static char rcsid[] = "$Id$";
34 segment_info_type segment_info[SEG_MAXIMUM_ORDINAL];
36 frchainS* frchain_root,
40 frchainS* frchain_root,
41 * frchain_now, /* Commented in "subsegs.h". */
45 char * const /* in: segT out: char* */
49 "e0","e1","e2","e3","e4","e5","e6","e7","e8","e9",
58 "ASSEMBLER-INTERNAL-LOGIC-ERROR!",
62 "transfert vector preload",
63 "transfert vector postload",
66 }; /* Used by error reporters, dumpers etc. */
72 /* Check table(s) seg_name[], seg_N_TYPE[] is in correct order */
75 know(SEG_ABSOLUTE == 0);
79 know(SEG_UNKNOWN == 4);
80 know(SEG_ABSENT == 5);
84 know(SEG_DIFFERENCE == 9);
85 know(SEG_DEBUG == 10);
88 know(SEG_REGISTER == 13);
89 know(SEG_MAXIMUM_ORDINAL == SEG_REGISTER );
90 /* know(segment_name(SEG_MAXIMUM_ORDINAL + 1)[0] == 0);*/
93 obstack_begin(&frags, 5000);
95 frchain_now = NULL; /* Warn new_subseg() that we are booting. */
96 /* Fake up 1st frag. */
97 /* It won't be used=> is ok if obstack... */
98 /* pads the end of it for alignment. */
99 frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
100 memset(frag_now, SIZEOF_STRUCT_FRAG, 0);
101 /* This 1st frag will not be in any frchain. */
102 /* We simply give subseg_new somewhere to scribble. */
103 now_subseg = 42; /* Lie for 1st call to subseg_new. */
107 for (i = SEG_E0; i < SEG_UNKNOWN; i++) {
109 segment_info[i].frchainP = frchain_now;
113 subseg_new(SEG_DATA, 0); /* .data 0 */
114 data0_frchainP = frchain_now;
122 * Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
123 * subsegment. If we are already in the correct subsegment, change nothing.
124 * This is used eg as a worker for subseg_new [which does make a new frag_now]
125 * and for changing segments after we have read the source. We construct eg
126 * fixSs even after the source file is read, so we do have to keep the
127 * segment context correct.
130 subseg_change (seg, subseg)
136 know(SEG_NORMAL(seg));
138 seg_fix_rootP = &segment_info[seg].fix_root;
139 seg_fix_tailP = &segment_info[seg].fix_tail;
143 seg_fix_rootP = &data_fix_root;
144 seg_fix_tailP = &data_fix_tail;
147 seg_fix_rootP = &text_fix_root;
148 seg_fix_tailP = &text_fix_tail;
151 seg_fix_rootP = &bss_fix_root;
152 seg_fix_tailP = &bss_fix_tail;
161 * If you attempt to change to the current subsegment, nothing happens.
163 * In: segT, subsegT code for new subsegment.
164 * frag_now -> incomplete frag for current subsegment.
165 * If frag_now == NULL, then there is no old, incomplete frag, so
166 * the old frag is not closed off.
168 * Out: now_subseg, now_seg updated.
169 * Frchain_now points to the (possibly new) struct frchain for this
171 * Frchain_root updated if needed.
175 subseg_new (seg, subseg) /* begin assembly for a new sub-segment */
176 register segT seg; /* SEG_DATA or SEG_TEXT */
177 register subsegT subseg;
179 long tmp; /* JF for obstack alignment hacking */
180 know(SEG_NORMAL(seg));
181 if (seg != now_seg || subseg != now_subseg)
182 { /* we just changed sub-segments */
183 register frchainS * frcP; /* crawl frchain chain */
184 register frchainS** lastPP; /* address of last pointer */
185 frchainS *newP; /* address of new frchain */
186 register fragS *former_last_fragP;
187 register fragS *new_fragP;
189 if (frag_now) /* If not bootstrapping. */
191 frag_now->fr_fix = obstack_next_free(& frags) - frag_now->fr_literal;
192 frag_wane(frag_now); /* Close off any frag in old subseg. */
195 * It would be nice to keep an obstack for each subsegment, if we swap
196 * subsegments a lot. Hence we would have much fewer frag_wanes().
200 obstack_finish( &frags);
202 * If we don't do the above, the next object we put on obstack frags
203 * will appear to start at the fr_literal of the current frag.
204 * Also, above ensures that the next object will begin on a
205 * address that is aligned correctly for the engine that runs
209 subseg_change (seg, (int)subseg);
211 * Attempt to find or make a frchain for that sub seg.
212 * Crawl along chain of frchainSs, begins @ frchain_root.
213 * If we need to make a frchainS, link it into correct
214 * position of chain rooted in frchain_root.
216 for (frcP = * (lastPP = & frchain_root);
218 && (int)(frcP->frch_seg) <= (int)seg;
219 frcP = * ( lastPP = & frcP->frch_next)
222 if ( (int)(frcP->frch_seg) == (int)seg
223 && frcP->frch_subseg >= subseg)
229 * frcP: Address of the 1st frchainS in correct segment with
230 * frch_subseg >= subseg.
231 * We want to either use this frchainS, or we want
232 * to insert a new frchainS just before it.
234 * If frcP == NULL, then we are at the end of the chain
235 * of frchainS-s. A NULL frcP means we fell off the end
236 * of the chain looking for a
237 * frch_subseg >= subseg, so we
238 * must make a new frchainS.
240 * If we ever maintain a pointer to
241 * the last frchainS in the chain, we change that pointer
242 * ONLY when frcP == NULL.
244 * lastPP: Address of the pointer with value frcP;
246 * May point to frchain_root.
250 || ( (int)(frcP->frch_seg) > (int)seg
251 || frcP->frch_subseg > subseg)) /* Kinky logic only works with 2 segments. */
254 * This should be the only code that creates a frchainS.
256 newP=(frchainS *)obstack_alloc(&frags,sizeof(frchainS));
257 memset(newP, sizeof(frchainS), 0);
258 /* This begines on a good boundary */
259 /* because a obstack_done() preceeded it. */
260 /* It implies an obstack_done(), so we */
261 /* expect the next object allocated to */
262 /* begin on a correct boundary. */
264 newP->frch_next = frcP; /* perhaps NULL */
265 (frcP = newP)->frch_subseg = subseg;
266 newP->frch_seg = seg;
267 newP->frch_last = NULL;
270 * Here with frcP->ing to the frchainS for subseg.
274 * Make a fresh frag for the subsegment.
276 /* We expect this to happen on a correct */
277 /* boundary since it was proceeded by a */
278 /* obstack_done(). */
279 tmp=obstack_alignment_mask(&frags); /* JF disable alignment */
280 obstack_alignment_mask(&frags)=0;
281 frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
282 obstack_alignment_mask(&frags)=tmp;
283 /* know(frags.obstack_c_next_free == frag_now->fr_literal); */
284 /* But we want any more chars to come */
285 /* immediately after the structure we just made. */
286 new_fragP = frag_now;
287 new_fragP->fr_next = NULL;
289 * Append new frag to current frchain.
291 former_last_fragP = frcP->frch_last;
292 if (former_last_fragP)
294 know( former_last_fragP->fr_next == NULL );
295 know( frchain_now->frch_root );
296 former_last_fragP->fr_next = new_fragP;
300 frcP->frch_root = new_fragP;
302 frcP->frch_last = new_fragP;
303 } /* if (changing subsegments) */
313 /* end of subsegs.c */