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) */
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