1 /* subsegs.c - subsegments -
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[] = "$Id$"; */
23 * Segments & sub-segments.
31 frchainS* frchain_root,
32 * frchain_now, /* Commented in "subsegs.h". */
36 char * const /* in: segT out: char* */
45 "ASSEMBLER-INTERNAL-LOGIC-ERROR!",
49 "transfert vector preload",
50 "transfert vector postload",
53 }; /* Used by error reporters, dumpers etc. */
59 /* Check table(s) seg_name[], seg_N_TYPE[] is in correct order */
60 know( SEG_ABSOLUTE == 0 );
61 know( SEG_TEXT == 1 );
62 know( SEG_DATA == 2 );
64 know( SEG_UNKNOWN == 4 );
65 know( SEG_ABSENT == 5 );
66 know( SEG_PASS1 == 6 );
67 know( SEG_GOOF == 7 );
69 know( SEG_DIFFERENCE == 9 );
70 know( SEG_DEBUG == 10 );
71 know( SEG_NTV == 11 );
72 know( SEG_PTV == 12 );
73 know( SEG_REGISTER == 13 );
74 know( SEG_MAXIMUM_ORDINAL == SEG_REGISTER );
75 know( segment_name (SEG_MAXIMUM_ORDINAL + 1) [0] == 0 );
77 obstack_begin( &frags, 5000);
79 frchain_now = NULL; /* Warn new_subseg() that we are booting. */
80 /* Fake up 1st frag. */
81 /* It won't be used=> is ok if obstack... */
82 /* pads the end of it for alignment. */
83 frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
84 /* obstack_1blank( &frags, SIZEOF_STRUCT_FRAG, & frag_now ); */
85 /* This 1st frag will not be in any frchain. */
86 /* We simply give subseg_new somewhere to scribble. */
87 now_subseg = 42; /* Lie for 1st call to subseg_new. */
88 subseg_new (SEG_DATA, 0); /* .data 0 */
89 data0_frchainP = frchain_now;
95 * Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
96 * subsegment. If we are already in the correct subsegment, change nothing.
97 * This is used eg as a worker for subseg_new [which does make a new frag_now]
98 * and for changing segments after we have read the source. We construct eg
99 * fixSs even after the source file is read, so we do have to keep the
100 * segment context correct.
103 subseg_change (seg, subseg)
111 seg_fix_rootP = & data_fix_root;
112 seg_fix_tailP = & data_fix_tail;
116 know (seg == SEG_TEXT);
117 seg_fix_rootP = & text_fix_root;
118 seg_fix_tailP = & text_fix_tail;
125 * If you attempt to change to the current subsegment, nothing happens.
127 * In: segT, subsegT code for new subsegment.
128 * frag_now -> incomplete frag for current subsegment.
129 * If frag_now==NULL, then there is no old, incomplete frag, so
130 * the old frag is not closed off.
132 * Out: now_subseg, now_seg updated.
133 * Frchain_now points to the (possibly new) struct frchain for this
135 * Frchain_root updated if needed.
139 subseg_new (seg, subseg) /* begin assembly for a new sub-segment */
140 register segT seg; /* SEG_DATA or SEG_TEXT */
141 register subsegT subseg;
143 long tmp; /* JF for obstack alignment hacking */
145 know( seg == SEG_DATA || seg == SEG_TEXT );
147 if (seg != now_seg || subseg != now_subseg)
148 { /* we just changed sub-segments */
149 register frchainS * frcP; /* crawl frchain chain */
150 register frchainS** lastPP; /* address of last pointer */
151 frchainS * newP; /* address of new frchain */
152 register fragS * former_last_fragP;
153 register fragS * new_fragP;
155 if (frag_now) /* If not bootstrapping. */
157 frag_now -> fr_fix = obstack_next_free(& frags) - frag_now -> fr_literal;
158 frag_wane(frag_now); /* Close off any frag in old subseg. */
161 * It would be nice to keep an obstack for each subsegment, if we swap
162 * subsegments a lot. Hence we would have much fewer frag_wanes().
166 obstack_finish( &frags);
168 * If we don't do the above, the next object we put on obstack frags
169 * will appear to start at the fr_literal of the current frag.
170 * Also, above ensures that the next object will begin on a
171 * address that is aligned correctly for the engine that runs
175 subseg_change (seg, (int)subseg);
177 * Attempt to find or make a frchain for that sub seg.
178 * Crawl along chain of frchainSs, begins @ frchain_root.
179 * If we need to make a frchainS, link it into correct
180 * position of chain rooted in frchain_root.
182 for (frcP = * (lastPP = & frchain_root);
184 && (int)(frcP -> frch_seg) <= (int)seg;
185 frcP = * ( lastPP = & frcP -> frch_next)
188 if ( (int)(frcP -> frch_seg) == (int)seg
189 && frcP -> frch_subseg >= subseg)
195 * frcP: Address of the 1st frchainS in correct segment with
196 * frch_subseg >= subseg.
197 * We want to either use this frchainS, or we want
198 * to insert a new frchainS just before it.
200 * If frcP==NULL, then we are at the end of the chain
201 * of frchainS-s. A NULL frcP means we fell off the end
202 * of the chain looking for a
203 * frch_subseg >= subseg, so we
204 * must make a new frchainS.
206 * If we ever maintain a pointer to
207 * the last frchainS in the chain, we change that pointer
208 * ONLY when frcP==NULL.
210 * lastPP: Address of the pointer with value frcP;
212 * May point to frchain_root.
216 || ( (int)(frcP -> frch_seg) > (int)seg
217 || frcP->frch_subseg > subseg)) /* Kinky logic only works with 2 segments. */
220 * This should be the only code that creates a frchainS.
222 newP=(frchainS *)obstack_alloc(&frags,sizeof(frchainS));
223 /* obstack_1blank( &frags, sizeof(frchainS), &newP); */
224 /* This begines on a good boundary */
225 /* because a obstack_done() preceeded it. */
226 /* It implies an obstack_done(), so we */
227 /* expect the next object allocated to */
228 /* begin on a correct boundary. */
230 newP -> frch_next = frcP; /* perhaps NULL */
231 (frcP = newP) -> frch_subseg = subseg;
232 newP -> frch_seg = seg;
233 newP -> frch_last = NULL;
236 * Here with frcP ->ing to the frchainS for subseg.
240 * Make a fresh frag for the subsegment.
242 /* We expect this to happen on a correct */
243 /* boundary since it was proceeded by a */
244 /* obstack_done(). */
245 tmp=obstack_alignment_mask(&frags); /* JF disable alignment */
246 obstack_alignment_mask(&frags)=0;
247 frag_now=(fragS *)obstack_alloc(&frags,SIZEOF_STRUCT_FRAG);
248 obstack_alignment_mask(&frags)=tmp;
249 /* know( frags . obstack_c_next_free == frag_now -> fr_literal ); */
250 /* But we want any more chars to come */
251 /* immediately after the structure we just made. */
252 new_fragP = frag_now;
253 new_fragP -> fr_next = NULL;
255 * Append new frag to current frchain.
257 former_last_fragP = frcP -> frch_last;
258 if (former_last_fragP)
260 know( former_last_fragP -> fr_next == NULL );
261 know( frchain_now -> frch_root );
262 former_last_fragP -> fr_next = new_fragP;
266 frcP -> frch_root = new_fragP;
268 frcP -> frch_last = new_fragP;
269 } /* if (changing subsegments) */