1 /* frags.c - manage frags -
2 Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 2000
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. */
34 zero_address_frag
.fr_type
= rs_fill
;
35 bss_address_frag
.fr_type
= rs_fill
;
38 /* Allocate a frag on the specified obstack.
39 Call this routine from everywhere else, so that all the weird alignment
40 hackery can be done in just one place. */
49 (void) obstack_alloc (ob
, 0);
50 oalign
= obstack_alignment_mask (ob
);
51 obstack_alignment_mask (ob
) = 0;
52 ptr
= (fragS
*) obstack_alloc (ob
, SIZEOF_STRUCT_FRAG
);
53 obstack_alignment_mask (ob
) = oalign
;
54 memset (ptr
, 0, SIZEOF_STRUCT_FRAG
);
58 /* Try to augment current frag by nchars chars.
59 If there is no room, close of the current frag with a ".fill 0"
60 and begin a new frag. Unless the new frag has nchars chars available
61 do not return. Do not set up any fields of *now_frag. */
67 if (obstack_room (&frchain_now
->frch_obstack
) < nchars
)
74 oldc
= frchain_now
->frch_obstack
.chunk_size
;
75 frchain_now
->frch_obstack
.chunk_size
= 2 * nchars
+ SIZEOF_STRUCT_FRAG
;
76 if (frchain_now
->frch_obstack
.chunk_size
> 0)
77 while ((n
= obstack_room (&frchain_now
->frch_obstack
)) < nchars
78 && (unsigned long) frchain_now
->frch_obstack
.chunk_size
> nchars
)
83 frchain_now
->frch_obstack
.chunk_size
= oldc
;
85 if (obstack_room (&frchain_now
->frch_obstack
) < nchars
)
86 as_fatal (_("Can't extend frag %d. chars"), nchars
);
89 /* Call this to close off a completed frag, and start up a new (empty)
90 frag, in the same subsegment as the old frag.
91 [frchain_now remains the same but frag_now is updated.]
92 Because this calculates the correct value of fr_fix by
93 looking at the obstack 'frags', it needs to know how many
94 characters at the end of the old frag belong to the maximal
95 variable part; The rest must belong to fr_fix.
96 It doesn't actually set up the old frag's fr_var. You may have
97 set fr_var == 1, but allocated 10 chars to the end of the frag;
98 In this case you pass old_frags_var_max_size == 10.
99 In fact, you may use fr_var for something totally unrelated to the
100 size of the variable part of the frag; None of the generic frag
101 handling code makes use of fr_var.
103 Make a new frag, initialising some components. Link new frag at end
107 frag_new (old_frags_var_max_size
)
108 /* Number of chars (already allocated on obstack frags) in
109 variable_length part of frag. */
110 int old_frags_var_max_size
;
112 fragS
*former_last_fragP
;
115 assert (frchain_now
->frch_last
== frag_now
);
117 /* Fix up old frag's fr_fix. */
118 frag_now
->fr_fix
= frag_now_fix_octets () - old_frags_var_max_size
;
119 /* Make sure its type is valid. */
120 assert (frag_now
->fr_type
!= 0);
122 /* This will align the obstack so the next struct we allocate on it
123 will begin at a correct boundary. */
124 obstack_finish (&frchain_now
->frch_obstack
);
127 former_last_fragP
= frchP
->frch_last
;
128 assert (former_last_fragP
!= 0);
129 assert (former_last_fragP
== frag_now
);
130 frag_now
= frag_alloc (&frchP
->frch_obstack
);
132 as_where (&frag_now
->fr_file
, &frag_now
->fr_line
);
134 /* Generally, frag_now->points to an address rounded up to next
135 alignment. However, characters will add to obstack frags
136 IMMEDIATELY after the struct frag, even if they are not starting
137 at an alignment address. */
138 former_last_fragP
->fr_next
= frag_now
;
139 frchP
->frch_last
= frag_now
;
143 extern struct list_info_struct
*listing_tail
;
144 frag_now
->line
= listing_tail
;
148 assert (frchain_now
->frch_last
== frag_now
);
150 frag_now
->fr_next
= NULL
;
153 /* Start a new frag unless we have n more chars of room in the current frag.
154 Close off the old frag with a .fill 0.
156 Return the address of the 1st char to write into. Advance
157 frag_now_growth past the new chars. */
163 register char *retval
;
165 if (now_seg
== absolute_section
)
167 as_bad (_("attempt to allocate data in absolute section"));
168 subseg_set (text_section
, 0);
171 if (mri_common_symbol
!= NULL
)
173 as_bad (_("attempt to allocate data in common section"));
174 mri_common_symbol
= NULL
;
178 retval
= obstack_next_free (&frchain_now
->frch_obstack
);
179 obstack_blank_fast (&frchain_now
->frch_obstack
, nchars
);
183 /* Start a new frag unless we have max_chars more chars of room in the
184 current frag. Close off the old frag with a .fill 0.
186 Set up a machine_dependent relaxable frag, then start a new frag.
187 Return the address of the 1st char of the var part of the old frag
191 frag_var (type
, max_chars
, var
, subtype
, symbol
, offset
, opcode
)
195 relax_substateT subtype
;
200 register char *retval
;
202 frag_grow (max_chars
);
203 retval
= obstack_next_free (&frchain_now
->frch_obstack
);
204 obstack_blank_fast (&frchain_now
->frch_obstack
, max_chars
);
205 frag_now
->fr_var
= var
;
206 frag_now
->fr_type
= type
;
207 frag_now
->fr_subtype
= subtype
;
208 frag_now
->fr_symbol
= symbol
;
209 frag_now
->fr_offset
= offset
;
210 frag_now
->fr_opcode
= opcode
;
212 frag_now
->fr_cgen
.insn
= 0;
213 frag_now
->fr_cgen
.opindex
= 0;
214 frag_now
->fr_cgen
.opinfo
= 0;
217 TC_FRAG_INIT (frag_now
);
219 as_where (&frag_now
->fr_file
, &frag_now
->fr_line
);
220 frag_new (max_chars
);
224 /* OVE: This variant of frag_var assumes that space for the tail has been
226 No call to frag_grow is done. */
229 frag_variant (type
, max_chars
, var
, subtype
, symbol
, offset
, opcode
)
233 relax_substateT subtype
;
238 register char *retval
;
240 retval
= obstack_next_free (&frchain_now
->frch_obstack
);
241 frag_now
->fr_var
= var
;
242 frag_now
->fr_type
= type
;
243 frag_now
->fr_subtype
= subtype
;
244 frag_now
->fr_symbol
= symbol
;
245 frag_now
->fr_offset
= offset
;
246 frag_now
->fr_opcode
= opcode
;
248 frag_now
->fr_cgen
.insn
= 0;
249 frag_now
->fr_cgen
.opindex
= 0;
250 frag_now
->fr_cgen
.opinfo
= 0;
253 TC_FRAG_INIT (frag_now
);
255 as_where (&frag_now
->fr_file
, &frag_now
->fr_line
);
256 frag_new (max_chars
);
260 /* Reduce the variable end of a frag to a harmless state. */
264 register fragS
*fragP
;
266 fragP
->fr_type
= rs_fill
;
267 fragP
->fr_offset
= 0;
271 /* Make an alignment frag. The size of this frag will be adjusted to
272 force the next frag to have the appropriate alignment. ALIGNMENT
273 is the power of two to which to align. FILL_CHARACTER is the
274 character to use to fill in any bytes which are skipped. MAX is
275 the maximum number of characters to skip when doing the alignment,
276 or 0 if there is no maximum. */
279 frag_align (alignment
, fill_character
, max
)
284 if (now_seg
== absolute_section
)
289 mask
= (~(addressT
) 0) << alignment
;
290 new_off
= (abs_section_offset
+ ~mask
) & mask
;
291 if (max
== 0 || new_off
- abs_section_offset
<= (addressT
) max
)
292 abs_section_offset
= new_off
;
298 p
= frag_var (rs_align
, 1, 1, (relax_substateT
) max
,
299 (symbolS
*) 0, (offsetT
) alignment
, (char *) 0);
304 /* Make an alignment frag like frag_align, but fill with a repeating
305 pattern rather than a single byte. ALIGNMENT is the power of two
306 to which to align. FILL_PATTERN is the fill pattern to repeat in
307 the bytes which are skipped. N_FILL is the number of bytes in
308 FILL_PATTERN. MAX is the maximum number of characters to skip when
309 doing the alignment, or 0 if there is no maximum. */
312 frag_align_pattern (alignment
, fill_pattern
, n_fill
, max
)
314 const char *fill_pattern
;
320 p
= frag_var (rs_align
, n_fill
, n_fill
, (relax_substateT
) max
,
321 (symbolS
*) 0, (offsetT
) alignment
, (char *) 0);
322 memcpy (p
, fill_pattern
, n_fill
);
326 frag_now_fix_octets ()
328 if (now_seg
== absolute_section
)
329 return abs_section_offset
;
331 return ((char *) obstack_next_free (&frchain_now
->frch_obstack
)
332 - frag_now
->fr_literal
);
338 return frag_now_fix_octets () / OCTETS_PER_BYTE
;
342 frag_append_1_char (datum
)
345 if (obstack_room (&frchain_now
->frch_obstack
) <= 1)
347 frag_wane (frag_now
);
350 obstack_1grow (&frchain_now
->frch_obstack
, datum
);
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