debugger/opcodes/obstack.h

   1 /* obstack.h - object stack macros
   2    Copyright (C) 1988, 89, 90, 91, 92, 93, 94 Free Software Foundation, Inc.
   3
   4 This program is free software; you can redistribute it and/or modify it
   5 under the terms of the GNU Library General Public License as published by the
   6 Free Software Foundation; either version 2, or (at your option) any
   7 later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Summary:
  19
  20 All the apparent functions defined here are macros. The idea
  21 is that you would use these pre-tested macros to solve a
  22 very specific set of problems, and they would run fast.
  23 Caution: no side-effects in arguments please!! They may be
  24 evaluated MANY times!!
  25
  26 These macros operate a stack of objects.  Each object starts life
  27 small, and may grow to maturity.  (Consider building a word syllable
  28 by syllable.)  An object can move while it is growing.  Once it has
  29 been "finished" it never changes address again.  So the "top of the
  30 stack" is typically an immature growing object, while the rest of the
  31 stack is of mature, fixed size and fixed address objects.
  32
  33 These routines grab large chunks of memory, using a function you
  34 supply, called `obstack_chunk_alloc'.  On occasion, they free chunks,
  35 by calling `obstack_chunk_free'.  You must define them and declare
  36 them before using any obstack macros.
  37
  38 Each independent stack is represented by a `struct obstack'.
  39 Each of the obstack macros expects a pointer to such a structure
  40 as the first argument.
  41
  42 One motivation for this package is the problem of growing char strings
  43 in symbol tables.  Unless you are "fascist pig with a read-only mind"
  44 --Gosper's immortal quote from HAKMEM item 154, out of context--you
  45 would not like to put any arbitrary upper limit on the length of your
  46 symbols.
  47
  48 In practice this often means you will build many short symbols and a
  49 few long symbols.  At the time you are reading a symbol you don't know
  50 how long it is.  One traditional method is to read a symbol into a
  51 buffer, realloc()ating the buffer every time you try to read a symbol
  52 that is longer than the buffer.  This is beaut, but you still will
  53 want to copy the symbol from the buffer to a more permanent
  54 symbol-table entry say about half the time.
  55
  56 With obstacks, you can work differently.  Use one obstack for all symbol
  57 names.  As you read a symbol, grow the name in the obstack gradually.
  58 When the name is complete, finalize it.  Then, if the symbol exists already,
  59 free the newly read name.
  60
  61 The way we do this is to take a large chunk, allocating memory from
  62 low addresses.  When you want to build a symbol in the chunk you just
  63 add chars above the current "high water mark" in the chunk.  When you
  64 have finished adding chars, because you got to the end of the symbol,
  65 you know how long the chars are, and you can create a new object.
  66 Mostly the chars will not burst over the highest address of the chunk,
  67 because you would typically expect a chunk to be (say) 100 times as
  68 long as an average object.
  69
  70 In case that isn't clear, when we have enough chars to make up
  71 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
  72 so we just point to it where it lies.  No moving of chars is
  73 needed and this is the second win: potentially long strings need
  74 never be explicitly shuffled. Once an object is formed, it does not
  75 change its address during its lifetime.
  76
  77 When the chars burst over a chunk boundary, we allocate a larger
  78 chunk, and then copy the partly formed object from the end of the old
  79 chunk to the beginning of the new larger chunk.  We then carry on
  80 accreting characters to the end of the object as we normally would.
  81
  82 A special macro is provided to add a single char at a time to a
  83 growing object.  This allows the use of register variables, which
  84 break the ordinary 'growth' macro.
  85
  86 Summary:
  87         We allocate large chunks.
  88         We carve out one object at a time from the current chunk.
  89         Once carved, an object never moves.
  90         We are free to append data of any size to the currently
  91           growing object.
  92         Exactly one object is growing in an obstack at any one time.
  93         You can run one obstack per control block.
  94         You may have as many control blocks as you dare.
  95         Because of the way we do it, you can `unwind' an obstack
  96           back to a previous state. (You may remove objects much
  97           as you would with a stack.)
  98 */
  99
 100
 101 /* Don't do the contents of this file more than once.  */
 102
 103 #ifndef __OBSTACK_H__
 104 #define __OBSTACK_H__
 105 \f
 106 /* We use subtraction of (char *)0 instead of casting to int
 107    because on word-addressable machines a simple cast to int
 108    may ignore the byte-within-word field of the pointer.  */
 109
 110 #ifndef __PTR_TO_INT
 111 #define __PTR_TO_INT(P) ((P) - (char *)0)
 112 #endif
 113
 114 #ifndef __INT_TO_PTR
 115 #define __INT_TO_PTR(P) ((P) + (char *)0)
 116 #endif
 117
 118 /* We need the type of the resulting object.  In ANSI C it is ptrdiff_t
 119    but in traditional C it is usually long.  If we are in ANSI C and
 120    don't already have ptrdiff_t get it.  */
 121
 122 #if defined (__STDC__) && ! defined (offsetof)
 123 #if defined (__GNUC__) && defined (IN_GCC)
 124 /* On Next machine, the system's stddef.h screws up if included
 125    after we have defined just ptrdiff_t, so include all of stddef.h.
 126    Otherwise, define just ptrdiff_t, which is all we need.  */
 127 #ifndef __NeXT__
 128 #define __need_ptrdiff_t
 129 #endif
 130 #endif
 131
 132 #include <stddef.h>
 133 #endif
 134
 135 #ifdef __STDC__
 136 #define PTR_INT_TYPE ptrdiff_t
 137 #else
 138 #define PTR_INT_TYPE long
 139 #endif
 140
 141 struct _obstack_chunk           /* Lives at front of each chunk. */
 142 {
 143   char  *limit;                 /* 1 past end of this chunk */
 144   struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
 145   char  contents[4];            /* objects begin here */
 146 };
 147
 148 struct obstack          /* control current object in current chunk */
 149 {
 150   long  chunk_size;             /* preferred size to allocate chunks in */
 151   struct _obstack_chunk* chunk; /* address of current struct obstack_chunk */
 152   char  *object_base;           /* address of object we are building */
 153   char  *next_free;             /* where to add next char to current object */
 154   char  *chunk_limit;           /* address of char after current chunk */
 155   PTR_INT_TYPE temp;            /* Temporary for some macros.  */
 156   int   alignment_mask;         /* Mask of alignment for each object. */
 157   struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk.  */
 158   void (*freefun) ();           /* User's function to free a chunk.  */
 159   char *extra_arg;              /* first arg for chunk alloc/dealloc funcs */
 160   unsigned use_extra_arg:1;     /* chunk alloc/dealloc funcs take extra arg */
 161   unsigned maybe_empty_object:1;/* There is a possibility that the current
 162                                    chunk contains a zero-length object.  This
 163                                    prevents freeing the chunk if we allocate
 164                                    a bigger chunk to replace it. */
 165   unsigned alloc_failed:1;      /* chunk alloc func returned 0 */
 166 };
 167
 168 /* Declare the external functions we use; they are in obstack.c.  */
 169
 170 #ifdef __STDC__
 171 extern void _obstack_newchunk (struct obstack *, int);
 172 extern void _obstack_free (struct obstack *, void *);
 173 extern int _obstack_begin (struct obstack *, int, int,
 174                             void *(*) (), void (*) ());
 175 extern int _obstack_begin_1 (struct obstack *, int, int,
 176                               void *(*) (), void (*) (), void *);
 177 #else
 178 extern void _obstack_newchunk ();
 179 extern void _obstack_free ();
 180 extern int _obstack_begin ();
 181 extern int _obstack_begin_1 ();
 182 #endif
 183 \f
 184 #ifdef __STDC__
 185
 186 /* Do the function-declarations after the structs
 187    but before defining the macros.  */
 188
 189 void obstack_init (struct obstack *obstack);
 190
 191 void * obstack_alloc (struct obstack *obstack, int size);
 192
 193 void * obstack_copy (struct obstack *obstack, void *address, int size);
 194 void * obstack_copy0 (struct obstack *obstack, void *address, int size);
 195
 196 void obstack_free (struct obstack *obstack, void *block);
 197
 198 void obstack_blank (struct obstack *obstack, int size);
 199
 200 void obstack_grow (struct obstack *obstack, void *data, int size);
 201 void obstack_grow0 (struct obstack *obstack, void *data, int size);
 202
 203 void obstack_1grow (struct obstack *obstack, int data_char);
 204 void obstack_ptr_grow (struct obstack *obstack, void *data);
 205 void obstack_int_grow (struct obstack *obstack, int data);
 206
 207 void * obstack_finish (struct obstack *obstack);
 208
 209 int obstack_object_size (struct obstack *obstack);
 210
 211 int obstack_room (struct obstack *obstack);
 212 void obstack_1grow_fast (struct obstack *obstack, int data_char);
 213 void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
 214 void obstack_int_grow_fast (struct obstack *obstack, int data);
 215 void obstack_blank_fast (struct obstack *obstack, int size);
 216
 217 void * obstack_base (struct obstack *obstack);
 218 void * obstack_next_free (struct obstack *obstack);
 219 int obstack_alignment_mask (struct obstack *obstack);
 220 int obstack_chunk_size (struct obstack *obstack);
 221
 222 #endif /* __STDC__ */
 223
 224 /* Non-ANSI C cannot really support alternative functions for these macros,
 225    so we do not declare them.  */
 226 \f
 227 /* Pointer to beginning of object being allocated or to be allocated next.
 228    Note that this might not be the final address of the object
 229    because a new chunk might be needed to hold the final size.  */
 230
 231 #define obstack_base(h) ((h)->alloc_failed ? 0 : (h)->object_base)
 232
 233 /* Size for allocating ordinary chunks.  */
 234
 235 #define obstack_chunk_size(h) ((h)->chunk_size)
 236
 237 /* Pointer to next byte not yet allocated in current chunk.  */
 238
 239 #define obstack_next_free(h)    ((h)->alloc_failed ? 0 : (h)->next_free)
 240
 241 /* Mask specifying low bits that should be clear in address of an object.  */
 242
 243 #define obstack_alignment_mask(h) ((h)->alignment_mask)
 244
 245 #define obstack_init(h) \
 246   _obstack_begin ((h), 0, 0, \
 247                   (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
 248
 249 #define obstack_begin(h, size) \
 250   _obstack_begin ((h), (size), 0, \
 251                   (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
 252
 253 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
 254   _obstack_begin ((h), (size), (alignment), \
 255                     (void *(*) ()) (chunkfun), (void (*) ()) (freefun))
 256
 257 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
 258   _obstack_begin_1 ((h), (size), (alignment), \
 259                     (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
 260
 261 #define obstack_chunkfun(h, newchunkfun) \
 262   ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
 263
 264 #define obstack_freefun(h, newfreefun) \
 265   ((h) -> freefun = (void (*)()) (newfreefun))
 266
 267 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
 268
 269 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
 270 \f
 271 #if defined (__GNUC__) && defined (__STDC__)
 272 #if __GNUC__ < 2
 273 #define __extension__
 274 #endif
 275
 276 /* For GNU C, if not -traditional,
 277    we can define these macros to compute all args only once
 278    without using a global variable.
 279    Also, we can avoid using the `temp' slot, to make faster code.  */
 280
 281 #define obstack_object_size(OBSTACK)                                    \
 282   __extension__                                                         \
 283   ({ struct obstack *__o = (OBSTACK);                                   \
 284      __o->alloc_failed ? 0 :                                            \
 285      (unsigned) (__o->next_free - __o->object_base); })
 286
 287 #define obstack_room(OBSTACK)                                           \
 288   __extension__                                                         \
 289   ({ struct obstack *__o = (OBSTACK);                                   \
 290      (unsigned) (__o->chunk_limit - __o->next_free); })
 291
 292 #define obstack_grow(OBSTACK,where,length)                              \
 293 __extension__                                                           \
 294 ({ struct obstack *__o = (OBSTACK);                                     \
 295    int __len = (length);                                                \
 296    if (__o->next_free + __len > __o->chunk_limit)                       \
 297      _obstack_newchunk (__o, __len);                                    \
 298    if (!__o->alloc_failed)                                              \
 299      {                                                                  \
 300         bcopy (where, __o->next_free, __len);                           \
 301         __o->next_free += __len;                                        \
 302      }                                                                  \
 303    (void) 0; })
 304
 305 #define obstack_grow0(OBSTACK,where,length)                             \
 306 __extension__                                                           \
 307 ({ struct obstack *__o = (OBSTACK);                                     \
 308    int __len = (length);                                                \
 309    if (__o->next_free + __len + 1 > __o->chunk_limit)                   \
 310      _obstack_newchunk (__o, __len + 1);                                \
 311    if (!__o->alloc_failed)                                              \
 312      {                                                                  \
 313        bcopy (where, __o->next_free, __len);                            \
 314        __o->next_free += __len;                                         \
 315        *(__o->next_free)++ = 0;                                         \
 316      }                                                                  \
 317    (void) 0; })
 318
 319 #define obstack_1grow(OBSTACK,datum)                                    \
 320 __extension__                                                           \
 321 ({ struct obstack *__o = (OBSTACK);                                     \
 322    if (__o->next_free + 1 > __o->chunk_limit)                           \
 323      _obstack_newchunk (__o, 1);                                        \
 324    if (!__o->alloc_failed)                                              \
 325      *(__o->next_free)++ = (datum);                                     \
 326    (void) 0; })
 327
 328 /* These assume that the obstack alignment is good enough for pointers or ints,
 329    and that the data added so far to the current object
 330    shares that much alignment.  */
 331
 332 #define obstack_ptr_grow(OBSTACK,datum)                                 \
 333 __extension__                                                           \
 334 ({ struct obstack *__o = (OBSTACK);                                     \
 335    if (__o->next_free + sizeof (void *) > __o->chunk_limit)             \
 336      _obstack_newchunk (__o, sizeof (void *));                          \
 337    if (!__o->alloc_failed)                                              \
 338      *((void **)__o->next_free)++ = ((void *)datum);                    \
 339    (void) 0; })
 340
 341 #define obstack_int_grow(OBSTACK,datum)                                 \
 342 __extension__                                                           \
 343 ({ struct obstack *__o = (OBSTACK);                                     \
 344    if (__o->next_free + sizeof (int) > __o->chunk_limit)                \
 345      _obstack_newchunk (__o, sizeof (int));                             \
 346    if (!__o->alloc_failed)                                              \
 347      *((int *)__o->next_free)++ = ((int)datum);                         \
 348    (void) 0; })
 349
 350 #define obstack_ptr_grow_fast(h,aptr) (*((void **)(h)->next_free)++ = (void *)aptr)
 351 #define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
 352
 353 #define obstack_blank(OBSTACK,length)                                   \
 354 __extension__                                                           \
 355 ({ struct obstack *__o = (OBSTACK);                                     \
 356    int __len = (length);                                                \
 357    if (__o->chunk_limit - __o->next_free < __len)                       \
 358      _obstack_newchunk (__o, __len);                                    \
 359    if (!__o->alloc_failed)                                              \
 360      __o->next_free += __len;                                           \
 361    (void) 0; })
 362
 363 #define obstack_alloc(OBSTACK,length)                                   \
 364 __extension__                                                           \
 365 ({ struct obstack *__h = (OBSTACK);                                     \
 366    obstack_blank (__h, (length));                                       \
 367    obstack_finish (__h); })
 368
 369 #define obstack_copy(OBSTACK,where,length)                              \
 370 __extension__                                                           \
 371 ({ struct obstack *__h = (OBSTACK);                                     \
 372    obstack_grow (__h, (where), (length));                               \
 373    obstack_finish (__h); })
 374
 375 #define obstack_copy0(OBSTACK,where,length)                             \
 376 __extension__                                                           \
 377 ({ struct obstack *__h = (OBSTACK);                                     \
 378    obstack_grow0 (__h, (where), (length));                              \
 379    obstack_finish (__h); })
 380
 381 /* The local variable is named __o1 to avoid a name conflict
 382    when obstack_blank is called.  */
 383 #define obstack_finish(OBSTACK)                                         \
 384 __extension__                                                           \
 385 ({ struct obstack *__o1 = (OBSTACK);                                    \
 386    void *value;                                                         \
 387    if (__o1->alloc_failed)                                              \
 388      value = 0;                                                         \
 389    else                                                                 \
 390      {                                                                  \
 391        value = (void *) __o1->object_base;                              \
 392        if (__o1->next_free == value)                                    \
 393          __o1->maybe_empty_object = 1;                                  \
 394        __o1->next_free                                                  \
 395          = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
 396                          & ~ (__o1->alignment_mask));                   \
 397        if (__o1->next_free - (char *)__o1->chunk                        \
 398            > __o1->chunk_limit - (char *)__o1->chunk)                   \
 399          __o1->next_free = __o1->chunk_limit;                           \
 400        __o1->object_base = __o1->next_free;                             \
 401       }                                                                 \
 402    value; })
 403
 404 #define obstack_free(OBSTACK, OBJ)                                      \
 405 __extension__                                                           \
 406 ({ struct obstack *__o = (OBSTACK);                                     \
 407    void *__obj = (OBJ);                                                 \
 408    if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit)  \
 409      __o->next_free = __o->object_base = __obj;                         \
 410    else (obstack_free) (__o, __obj); })
 411 \f
 412 #else /* not __GNUC__ or not __STDC__ */
 413
 414 #define obstack_object_size(h) \
 415  (unsigned) ((h)->alloc_failed ? 0 : (h)->next_free - (h)->object_base)
 416
 417 #define obstack_room(h)         \
 418  (unsigned) ((h)->chunk_limit - (h)->next_free)
 419
 420 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
 421    so that we can avoid having void expressions
 422    in the arms of the conditional expression.
 423    Casting the third operand to void was tried before,
 424    but some compilers won't accept it.  */
 425
 426 #define obstack_grow(h,where,length)                                    \
 427 ( (h)->temp = (length),                                                 \
 428   (((h)->next_free + (h)->temp > (h)->chunk_limit)                      \
 429    ? (_obstack_newchunk ((h), (h)->temp), 0) : 0),                      \
 430   ((h)->alloc_failed ? 0 :                                              \
 431   (bcopy (where, (h)->next_free, (h)->temp),                            \
 432   (h)->next_free += (h)->temp)))
 433
 434 #define obstack_grow0(h,where,length)                                   \
 435 ( (h)->temp = (length),                                                 \
 436   (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit)                  \
 437    ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0),                  \
 438   ((h)->alloc_failed ? 0 :                                              \
 439   (bcopy (where, (h)->next_free, (h)->temp),                            \
 440   (h)->next_free += (h)->temp,                                          \
 441   *((h)->next_free)++ = 0)))
 442
 443 #define obstack_1grow(h,datum)                                          \
 444 ( (((h)->next_free + 1 > (h)->chunk_limit)                              \
 445    ? (_obstack_newchunk ((h), 1), 0) : 0),                              \
 446  ((h)->alloc_failed ? 0 :                                               \
 447   (*((h)->next_free)++ = (datum))))
 448
 449 #define obstack_ptr_grow(h,datum)                                       \
 450 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit)                \
 451    ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0),                \
 452   ((h)->alloc_failed ? 0 :                                              \
 453   (*((char **)(((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *)datum))))
 454
 455 #define obstack_int_grow(h,datum)                                       \
 456 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit)                   \
 457    ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0),                   \
 458   ((h)->alloc_failed ? 0 :                                              \
 459   (*((int *)(((h)->next_free+=sizeof(int))-sizeof(int))) = ((int)datum))))
 460
 461 #define obstack_ptr_grow_fast(h,aptr) (*((char **)(h)->next_free)++ = (char *)aptr)
 462 #define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
 463
 464 #define obstack_blank(h,length)                                         \
 465 ( (h)->temp = (length),                                                 \
 466   (((h)->chunk_limit - (h)->next_free < (h)->temp)                      \
 467    ? (_obstack_newchunk ((h), (h)->temp), 0) : 0),                      \
 468   ((h)->alloc_failed ? 0 :                                              \
 469   ((h)->next_free += (h)->temp)))
 470
 471 #define obstack_alloc(h,length)                                         \
 472  (obstack_blank ((h), (length)), obstack_finish ((h)))
 473
 474 #define obstack_copy(h,where,length)                                    \
 475  (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
 476
 477 #define obstack_copy0(h,where,length)                                   \
 478  (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
 479
 480 #define obstack_finish(h)                                               \
 481 ( (h)->alloc_failed ? 0 :                                               \
 482   (((h)->next_free == (h)->object_base                                  \
 483    ? (((h)->maybe_empty_object = 1), 0)                                 \
 484    : 0),                                                                \
 485   (h)->temp = __PTR_TO_INT ((h)->object_base),                          \
 486   (h)->next_free                                                        \
 487     = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
 488                     & ~ ((h)->alignment_mask)),                         \
 489   (((h)->next_free - (char *)(h)->chunk                                 \
 490     > (h)->chunk_limit - (char *)(h)->chunk)                            \
 491    ? ((h)->next_free = (h)->chunk_limit) : 0),                          \
 492   (h)->object_base = (h)->next_free,                                    \
 493   __INT_TO_PTR ((h)->temp)))
 494
 495 #ifdef __STDC__
 496 #define obstack_free(h,obj)                                             \
 497 ( (h)->temp = (char *)(obj) - (char *) (h)->chunk,                      \
 498   (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
 499    ? (int) ((h)->next_free = (h)->object_base                           \
 500             = (h)->temp + (char *) (h)->chunk)                          \
 501    : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
 502 #else
 503 #define obstack_free(h,obj)                                             \
 504 ( (h)->temp = (char *)(obj) - (char *) (h)->chunk,                      \
 505   (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
 506    ? (int) ((h)->next_free = (h)->object_base                           \
 507             = (h)->temp + (char *) (h)->chunk)                          \
 508    : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
 509 #endif
 510
 511 #endif /* not __GNUC__ or not __STDC__ */
 512
 513 #endif /* not __OBSTACK_H__ */