Xenomai  3.0.8
obstack.h
1 /* obstack.h - object stack macros
2  Copyright (C) 1988-1994,1996-1999,2003,2004,2005
3  Free Software Foundation, Inc.
4  This file is part of the GNU C Library.
5 
6  The GNU C Library is free software; you can redistribute it and/or
7  modify it under the terms of the GNU Lesser General Public
8  License as published by the Free Software Foundation; either
9  version 2.1 of the License, or (at your option) any later version.
10 
11  The GNU C Library 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 GNU
14  Lesser General Public License for more details.
15 
16  You should have received a copy of the GNU Lesser General Public
17  License along with the GNU C Library; if not, write to the Free
18  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
19  Boston, MA 02110-1301, USA. */
20 
21 /* Summary:
22 
23 All the apparent functions defined here are macros. The idea
24 is that you would use these pre-tested macros to solve a
25 very specific set of problems, and they would run fast.
26 Caution: no side-effects in arguments please!! They may be
27 evaluated MANY times!!
28 
29 These macros operate a stack of objects. Each object starts life
30 small, and may grow to maturity. (Consider building a word syllable
31 by syllable.) An object can move while it is growing. Once it has
32 been "finished" it never changes address again. So the "top of the
33 stack" is typically an immature growing object, while the rest of the
34 stack is of mature, fixed size and fixed address objects.
35 
36 These routines grab large chunks of memory, using a function you
37 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
38 by calling `obstack_chunk_free'. You must define them and declare
39 them before using any obstack macros.
40 
41 Each independent stack is represented by a `struct obstack'.
42 Each of the obstack macros expects a pointer to such a structure
43 as the first argument.
44 
45 One motivation for this package is the problem of growing char strings
46 in symbol tables. Unless you are "fascist pig with a read-only mind"
47 --Gosper's immortal quote from HAKMEM item 154, out of context--you
48 would not like to put any arbitrary upper limit on the length of your
49 symbols.
50 
51 In practice this often means you will build many short symbols and a
52 few long symbols. At the time you are reading a symbol you don't know
53 how long it is. One traditional method is to read a symbol into a
54 buffer, realloc()ating the buffer every time you try to read a symbol
55 that is longer than the buffer. This is beaut, but you still will
56 want to copy the symbol from the buffer to a more permanent
57 symbol-table entry say about half the time.
58 
59 With obstacks, you can work differently. Use one obstack for all symbol
60 names. As you read a symbol, grow the name in the obstack gradually.
61 When the name is complete, finalize it. Then, if the symbol exists already,
62 free the newly read name.
63 
64 The way we do this is to take a large chunk, allocating memory from
65 low addresses. When you want to build a symbol in the chunk you just
66 add chars above the current "high water mark" in the chunk. When you
67 have finished adding chars, because you got to the end of the symbol,
68 you know how long the chars are, and you can create a new object.
69 Mostly the chars will not burst over the highest address of the chunk,
70 because you would typically expect a chunk to be (say) 100 times as
71 long as an average object.
72 
73 In case that isn't clear, when we have enough chars to make up
74 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
75 so we just point to it where it lies. No moving of chars is
76 needed and this is the second win: potentially long strings need
77 never be explicitly shuffled. Once an object is formed, it does not
78 change its address during its lifetime.
79 
80 When the chars burst over a chunk boundary, we allocate a larger
81 chunk, and then copy the partly formed object from the end of the old
82 chunk to the beginning of the new larger chunk. We then carry on
83 accreting characters to the end of the object as we normally would.
84 
85 A special macro is provided to add a single char at a time to a
86 growing object. This allows the use of register variables, which
87 break the ordinary 'growth' macro.
88 
89 Summary:
90  We allocate large chunks.
91  We carve out one object at a time from the current chunk.
92  Once carved, an object never moves.
93  We are free to append data of any size to the currently
94  growing object.
95  Exactly one object is growing in an obstack at any one time.
96  You can run one obstack per control block.
97  You may have as many control blocks as you dare.
98  Because of the way we do it, you can `unwind' an obstack
99  back to a previous state. (You may remove objects much
100  as you would with a stack.)
101 */
102 
103 
104 /* Don't do the contents of this file more than once. */
105 
106 #ifndef _BOILERPLATE_OBSTACK_H
107 #define _BOILERPLATE_OBSTACK_H 1
108 
109 #ifdef HAVE_OBSTACK_H
110 #include_next <obstack.h>
111 #else
112 
113 #ifdef __cplusplus
114 extern "C" {
115 #endif
116 
117 /* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is
118  defined, as with GNU C, use that; that way we don't pollute the
119  namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h>
120  and use ptrdiff_t. */
121 
122 #ifdef __PTRDIFF_TYPE__
123 # define PTR_INT_TYPE __PTRDIFF_TYPE__
124 #else
125 # include <stddef.h>
126 # define PTR_INT_TYPE ptrdiff_t
127 #endif
128 
129 /* If B is the base of an object addressed by P, return the result of
130  aligning P to the next multiple of A + 1. B and P must be of type
131  char *. A + 1 must be a power of 2. */
132 
133 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
134 
135 /* Similiar to _BPTR_ALIGN (B, P, A), except optimize the common case
136  where pointers can be converted to integers, aligned as integers,
137  and converted back again. If PTR_INT_TYPE is narrower than a
138  pointer (e.g., the AS/400), play it safe and compute the alignment
139  relative to B. Otherwise, use the faster strategy of computing the
140  alignment relative to 0. */
141 
142 #define __PTR_ALIGN(B, P, A) \
143  __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \
144  P, A)
145 
146 #include <string.h>
147 
148 struct _obstack_chunk /* Lives at front of each chunk. */
149 {
150  char *limit; /* 1 past end of this chunk */
151  struct _obstack_chunk *prev; /* address of prior chunk or NULL */
152  char contents[4]; /* objects begin here */
153 };
154 
155 struct obstack /* control current object in current chunk */
156 {
157  long chunk_size; /* preferred size to allocate chunks in */
158  struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
159  char *object_base; /* address of object we are building */
160  char *next_free; /* where to add next char to current object */
161  char *chunk_limit; /* address of char after current chunk */
162  union
163  {
164  PTR_INT_TYPE tempint;
165  void *tempptr;
166  } temp; /* Temporary for some macros. */
167  int alignment_mask; /* Mask of alignment for each object. */
168  /* These prototypes vary based on `use_extra_arg', and we use
169  casts to the prototypeless function type in all assignments,
170  but having prototypes here quiets -Wstrict-prototypes. */
171  struct _obstack_chunk *(*chunkfun) (void *, long);
172  void (*freefun) (void *, struct _obstack_chunk *);
173  void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
174  unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
175  unsigned maybe_empty_object:1;/* There is a possibility that the current
176  chunk contains a zero-length object. This
177  prevents freeing the chunk if we allocate
178  a bigger chunk to replace it. */
179  unsigned alloc_failed:1; /* No longer used, as we now call the failed
180  handler on error, but retained for binary
181  compatibility. */
182 };
183 
184 /* Declare the external functions we use; they are in obstack.c. */
185 
186 extern void _obstack_newchunk (struct obstack *, int);
187 extern int _obstack_begin (struct obstack *, int, int,
188  void *(*) (long), void (*) (void *));
189 extern int _obstack_begin_1 (struct obstack *, int, int,
190  void *(*) (void *, long),
191  void (*) (void *, void *), void *);
192 extern int _obstack_memory_used (struct obstack *);
193 
194 void obstack_free (struct obstack *obstack, void *block);
195 
196 
197 /* Error handler called when `obstack_chunk_alloc' failed to allocate
198  more memory. This can be set to a user defined function which
199  should either abort gracefully or use longjump - but shouldn't
200  return. The default action is to print a message and abort. */
201 extern void (*obstack_alloc_failed_handler) (void);
202 
203 /* Exit value used when `print_and_abort' is used. */
204 extern int obstack_exit_failure;
205 
206 /* Pointer to beginning of object being allocated or to be allocated next.
207  Note that this might not be the final address of the object
208  because a new chunk might be needed to hold the final size. */
209 
210 #define obstack_base(h) ((void *) (h)->object_base)
211 
212 /* Size for allocating ordinary chunks. */
213 
214 #define obstack_chunk_size(h) ((h)->chunk_size)
215 
216 /* Pointer to next byte not yet allocated in current chunk. */
217 
218 #define obstack_next_free(h) ((h)->next_free)
219 
220 /* Mask specifying low bits that should be clear in address of an object. */
221 
222 #define obstack_alignment_mask(h) ((h)->alignment_mask)
223 
224 /* To prevent prototype warnings provide complete argument list. */
225 #define obstack_init(h) \
226  _obstack_begin ((h), 0, 0, \
227  (void *(*) (long)) obstack_chunk_alloc, \
228  (void (*) (void *)) obstack_chunk_free)
229 
230 #define obstack_begin(h, size) \
231  _obstack_begin ((h), (size), 0, \
232  (void *(*) (long)) obstack_chunk_alloc, \
233  (void (*) (void *)) obstack_chunk_free)
234 
235 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
236  _obstack_begin ((h), (size), (alignment), \
237  (void *(*) (long)) (chunkfun), \
238  (void (*) (void *)) (freefun))
239 
240 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
241  _obstack_begin_1 ((h), (size), (alignment), \
242  (void *(*) (void *, long)) (chunkfun), \
243  (void (*) (void *, void *)) (freefun), (arg))
244 
245 #define obstack_chunkfun(h, newchunkfun) \
246  ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
247 
248 #define obstack_freefun(h, newfreefun) \
249  ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
250 
251 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar))
252 
253 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
254 
255 #define obstack_memory_used(h) _obstack_memory_used (h)
256 
257 #if defined __GNUC__ && defined __STDC__ && __STDC__
258 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
259  does not implement __extension__. But that compiler doesn't define
260  __GNUC_MINOR__. */
261 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
262 # define __extension__
263 # endif
264 
265 /* For GNU C, if not -traditional,
266  we can define these macros to compute all args only once
267  without using a global variable.
268  Also, we can avoid using the `temp' slot, to make faster code. */
269 
270 # define obstack_object_size(OBSTACK) \
271  __extension__ \
272  ({ struct obstack const *__o = (OBSTACK); \
273  (unsigned) (__o->next_free - __o->object_base); })
274 
275 # define obstack_room(OBSTACK) \
276  __extension__ \
277  ({ struct obstack const *__o = (OBSTACK); \
278  (unsigned) (__o->chunk_limit - __o->next_free); })
279 
280 # define obstack_make_room(OBSTACK,length) \
281 __extension__ \
282 ({ struct obstack *__o = (OBSTACK); \
283  int __len = (length); \
284  if (__o->chunk_limit - __o->next_free < __len) \
285  _obstack_newchunk (__o, __len); \
286  (void) 0; })
287 
288 # define obstack_empty_p(OBSTACK) \
289  __extension__ \
290  ({ struct obstack const *__o = (OBSTACK); \
291  (__o->chunk->prev == 0 \
292  && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \
293  __o->chunk->contents, \
294  __o->alignment_mask)); })
295 
296 # define obstack_grow(OBSTACK,where,length) \
297 __extension__ \
298 ({ struct obstack *__o = (OBSTACK); \
299  int __len = (length); \
300  if (__o->next_free + __len > __o->chunk_limit) \
301  _obstack_newchunk (__o, __len); \
302  memcpy (__o->next_free, where, __len); \
303  __o->next_free += __len; \
304  (void) 0; })
305 
306 # define obstack_grow0(OBSTACK,where,length) \
307 __extension__ \
308 ({ struct obstack *__o = (OBSTACK); \
309  int __len = (length); \
310  if (__o->next_free + __len + 1 > __o->chunk_limit) \
311  _obstack_newchunk (__o, __len + 1); \
312  memcpy (__o->next_free, where, __len); \
313  __o->next_free += __len; \
314  *(__o->next_free)++ = 0; \
315  (void) 0; })
316 
317 # define obstack_1grow(OBSTACK,datum) \
318 __extension__ \
319 ({ struct obstack *__o = (OBSTACK); \
320  if (__o->next_free + 1 > __o->chunk_limit) \
321  _obstack_newchunk (__o, 1); \
322  obstack_1grow_fast (__o, datum); \
323  (void) 0; })
324 
325 /* These assume that the obstack alignment is good enough for pointers
326  or ints, and that the data added so far to the current object
327  shares that much alignment. */
328 
329 # define obstack_ptr_grow(OBSTACK,datum) \
330 __extension__ \
331 ({ struct obstack *__o = (OBSTACK); \
332  if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
333  _obstack_newchunk (__o, sizeof (void *)); \
334  obstack_ptr_grow_fast (__o, datum); }) \
335 
336 # define obstack_int_grow(OBSTACK,datum) \
337 __extension__ \
338 ({ struct obstack *__o = (OBSTACK); \
339  if (__o->next_free + sizeof (int) > __o->chunk_limit) \
340  _obstack_newchunk (__o, sizeof (int)); \
341  obstack_int_grow_fast (__o, datum); })
342 
343 # define obstack_ptr_grow_fast(OBSTACK,aptr) \
344 __extension__ \
345 ({ struct obstack *__o1 = (OBSTACK); \
346  *(const void **) __o1->next_free = (aptr); \
347  __o1->next_free += sizeof (const void *); \
348  (void) 0; })
349 
350 # define obstack_int_grow_fast(OBSTACK,aint) \
351 __extension__ \
352 ({ struct obstack *__o1 = (OBSTACK); \
353  *(int *) __o1->next_free = (aint); \
354  __o1->next_free += sizeof (int); \
355  (void) 0; })
356 
357 # define obstack_blank(OBSTACK,length) \
358 __extension__ \
359 ({ struct obstack *__o = (OBSTACK); \
360  int __len = (length); \
361  if (__o->chunk_limit - __o->next_free < __len) \
362  _obstack_newchunk (__o, __len); \
363  obstack_blank_fast (__o, __len); \
364  (void) 0; })
365 
366 # define obstack_alloc(OBSTACK,length) \
367 __extension__ \
368 ({ struct obstack *__h = (OBSTACK); \
369  obstack_blank (__h, (length)); \
370  obstack_finish (__h); })
371 
372 # define obstack_copy(OBSTACK,where,length) \
373 __extension__ \
374 ({ struct obstack *__h = (OBSTACK); \
375  obstack_grow (__h, (where), (length)); \
376  obstack_finish (__h); })
377 
378 # define obstack_copy0(OBSTACK,where,length) \
379 __extension__ \
380 ({ struct obstack *__h = (OBSTACK); \
381  obstack_grow0 (__h, (where), (length)); \
382  obstack_finish (__h); })
383 
384 /* The local variable is named __o1 to avoid a name conflict
385  when obstack_blank is called. */
386 # define obstack_finish(OBSTACK) \
387 __extension__ \
388 ({ struct obstack *__o1 = (OBSTACK); \
389  void *__value = (void *) __o1->object_base; \
390  if (__o1->next_free == __value) \
391  __o1->maybe_empty_object = 1; \
392  __o1->next_free \
393  = __PTR_ALIGN (__o1->object_base, __o1->next_free, \
394  __o1->alignment_mask); \
395  if (__o1->next_free - (char *)__o1->chunk \
396  > __o1->chunk_limit - (char *)__o1->chunk) \
397  __o1->next_free = __o1->chunk_limit; \
398  __o1->object_base = __o1->next_free; \
399  __value; })
400 
401 # define obstack_free(OBSTACK, OBJ) \
402 __extension__ \
403 ({ struct obstack *__o = (OBSTACK); \
404  void *__obj = (OBJ); \
405  if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
406  __o->next_free = __o->object_base = (char *)__obj; \
407  else (obstack_free) (__o, __obj); })
408 
409 #else /* not __GNUC__ or not __STDC__ */
410 
411 # define obstack_object_size(h) \
412  (unsigned) ((h)->next_free - (h)->object_base)
413 
414 # define obstack_room(h) \
415  (unsigned) ((h)->chunk_limit - (h)->next_free)
416 
417 # define obstack_empty_p(h) \
418  ((h)->chunk->prev == 0 \
419  && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \
420  (h)->chunk->contents, \
421  (h)->alignment_mask))
422 
423 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
424  so that we can avoid having void expressions
425  in the arms of the conditional expression.
426  Casting the third operand to void was tried before,
427  but some compilers won't accept it. */
428 
429 # define obstack_make_room(h,length) \
430 ( (h)->temp.tempint = (length), \
431  (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
432  ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0))
433 
434 # define obstack_grow(h,where,length) \
435 ( (h)->temp.tempint = (length), \
436  (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
437  ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
438  memcpy ((h)->next_free, where, (h)->temp.tempint), \
439  (h)->next_free += (h)->temp.tempint)
440 
441 # define obstack_grow0(h,where,length) \
442 ( (h)->temp.tempint = (length), \
443  (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \
444  ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \
445  memcpy ((h)->next_free, where, (h)->temp.tempint), \
446  (h)->next_free += (h)->temp.tempint, \
447  *((h)->next_free)++ = 0)
448 
449 # define obstack_1grow(h,datum) \
450 ( (((h)->next_free + 1 > (h)->chunk_limit) \
451  ? (_obstack_newchunk ((h), 1), 0) : 0), \
452  obstack_1grow_fast (h, datum))
453 
454 # define obstack_ptr_grow(h,datum) \
455 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
456  ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
457  obstack_ptr_grow_fast (h, datum))
458 
459 # define obstack_int_grow(h,datum) \
460 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
461  ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
462  obstack_int_grow_fast (h, datum))
463 
464 # define obstack_ptr_grow_fast(h,aptr) \
465  (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr))
466 
467 # define obstack_int_grow_fast(h,aint) \
468  (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint))
469 
470 # define obstack_blank(h,length) \
471 ( (h)->temp.tempint = (length), \
472  (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \
473  ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
474  obstack_blank_fast (h, (h)->temp.tempint))
475 
476 # define obstack_alloc(h,length) \
477  (obstack_blank ((h), (length)), obstack_finish ((h)))
478 
479 # define obstack_copy(h,where,length) \
480  (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
481 
482 # define obstack_copy0(h,where,length) \
483  (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
484 
485 # define obstack_finish(h) \
486 ( ((h)->next_free == (h)->object_base \
487  ? (((h)->maybe_empty_object = 1), 0) \
488  : 0), \
489  (h)->temp.tempptr = (h)->object_base, \
490  (h)->next_free \
491  = __PTR_ALIGN ((h)->object_base, (h)->next_free, \
492  (h)->alignment_mask), \
493  (((h)->next_free - (char *) (h)->chunk \
494  > (h)->chunk_limit - (char *) (h)->chunk) \
495  ? ((h)->next_free = (h)->chunk_limit) : 0), \
496  (h)->object_base = (h)->next_free, \
497  (h)->temp.tempptr)
498 
499 # define obstack_free(h,obj) \
500 ( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \
501  ((((h)->temp.tempint > 0 \
502  && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \
503  ? (int) ((h)->next_free = (h)->object_base \
504  = (h)->temp.tempint + (char *) (h)->chunk) \
505  : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0)))
506 
507 #endif /* not __GNUC__ or not __STDC__ */
508 
509 #ifdef __cplusplus
510 } /* C++ */
511 #endif
512 
513 #endif /* !HAVE_OBSTACK_H */
514 
515 #endif /* _BOILERPLATE_OBSTACK_H */