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Annotation of gcc/obstack.c, revision 1.1

1.1     ! root        1: /* obstack.c - subroutines used implicitly by object stack macros
        !             2:    Copyright (C) 1988 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 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 General Public License for more details.
        !            13: 
        !            14: You should have received a copy of the GNU 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: #include "obstack.h"
        !            19: 
        !            20: #ifdef __STDC__
        !            21: #define POINTER void *
        !            22: #else
        !            23: #define POINTER char *
        !            24: #endif
        !            25: 
        !            26: /* Determine default alignment.  */
        !            27: struct fooalign {char x; double d;};
        !            28: #define DEFAULT_ALIGNMENT ((char *)&((struct fooalign *) 0)->d - (char *)0)
        !            29: /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
        !            30:    But in fact it might be less smart and round addresses to as much as
        !            31:    DEFAULT_ROUNDING.  So we prepare for it to do that.  */
        !            32: union fooround {long x; double d;};
        !            33: #define DEFAULT_ROUNDING (sizeof (union fooround))
        !            34: 
        !            35: /* When we copy a long block of data, this is the unit to do it with.
        !            36:    On some machines, copying successive ints does not work;
        !            37:    in such a case, redefine COPYING_UNIT to `long' (if that works)
        !            38:    or `char' as a last resort.  */
        !            39: #ifndef COPYING_UNIT
        !            40: #define COPYING_UNIT int
        !            41: #endif
        !            42: 
        !            43: /* The non-GNU-C macros copy the obstack into this global variable
        !            44:    to avoid multiple evaluation.  */
        !            45: 
        !            46: struct obstack *_obstack;
        !            47: 
        !            48: /* Initialize an obstack H for use.  Specify chunk size SIZE (0 means default).
        !            49:    Objects start on multiples of ALIGNMENT (0 means use default).
        !            50:    CHUNKFUN is the function to use to allocate chunks,
        !            51:    and FREEFUN the function to free them.  */
        !            52: 
        !            53: void
        !            54: _obstack_begin (h, size, alignment, chunkfun, freefun)
        !            55:      struct obstack *h;
        !            56:      int size;
        !            57:      int alignment;
        !            58:      POINTER (*chunkfun) ();
        !            59:      void (*freefun) ();
        !            60: {
        !            61:   register struct _obstack_chunk* chunk; /* points to new chunk */
        !            62: 
        !            63:   if (alignment == 0)
        !            64:     alignment = DEFAULT_ALIGNMENT;
        !            65:   if (size == 0)
        !            66:     /* Default size is what GNU malloc can fit in a 4096-byte block.  */
        !            67:     {
        !            68:       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
        !            69:         Use the values for range checking, because if range checking is off,
        !            70:         the extra bytes won't be missed terribly, but if range checking is on
        !            71:         and we used a larger request, a whole extra 4096 bytes would be
        !            72:         allocated.
        !            73: 
        !            74:         These number are irrelevant to the new GNU malloc.  I suspect it is
        !            75:         less sensitive to the size of the request.  */
        !            76:       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
        !            77:                    + 4 + DEFAULT_ROUNDING - 1)
        !            78:                   & ~(DEFAULT_ROUNDING - 1));
        !            79:       size = 4096 - extra;
        !            80:     }
        !            81: 
        !            82:   h->chunkfun = (struct _obstack_chunk * (*)()) chunkfun;
        !            83:   h->freefun = freefun;
        !            84:   h->chunk_size = size;
        !            85:   h->alignment_mask = alignment - 1;
        !            86: 
        !            87:   chunk        = h->chunk = (*h->chunkfun) (h->chunk_size);
        !            88:   h->next_free = h->object_base = chunk->contents;
        !            89:   h->chunk_limit = chunk->limit
        !            90:     = (char *) chunk + h->chunk_size;
        !            91:   chunk->prev = 0;
        !            92:   /* The initial chunk now contains no empty object.  */
        !            93:   h->maybe_empty_object = 0;
        !            94: }
        !            95: 
        !            96: /* Allocate a new current chunk for the obstack *H
        !            97:    on the assumption that LENGTH bytes need to be added
        !            98:    to the current object, or a new object of length LENGTH allocated.
        !            99:    Copies any partial object from the end of the old chunk
        !           100:    to the beginning of the new one.  */
        !           101: 
        !           102: void
        !           103: _obstack_newchunk (h, length)
        !           104:      struct obstack *h;
        !           105:      int length;
        !           106: {
        !           107:   register struct _obstack_chunk*      old_chunk = h->chunk;
        !           108:   register struct _obstack_chunk*      new_chunk;
        !           109:   register long        new_size;
        !           110:   register int obj_size = h->next_free - h->object_base;
        !           111:   register int i;
        !           112:   int already;
        !           113: 
        !           114:   /* Compute size for new chunk.  */
        !           115:   new_size = (obj_size + length) + (obj_size >> 3) + 100;
        !           116:   if (new_size < h->chunk_size)
        !           117:     new_size = h->chunk_size;
        !           118: 
        !           119:   /* Allocate and initialize the new chunk.  */
        !           120:   new_chunk = h->chunk = (*h->chunkfun) (new_size);
        !           121:   new_chunk->prev = old_chunk;
        !           122:   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
        !           123: 
        !           124:   /* Move the existing object to the new chunk.
        !           125:      Word at a time is fast and is safe if the object
        !           126:      is sufficiently aligned.  */
        !           127:   if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
        !           128:     {
        !           129:       for (i = obj_size / sizeof (COPYING_UNIT) - 1;
        !           130:           i >= 0; i--)
        !           131:        ((COPYING_UNIT *)new_chunk->contents)[i]
        !           132:          = ((COPYING_UNIT *)h->object_base)[i];
        !           133:       /* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
        !           134:         but that can cross a page boundary on a machine
        !           135:         which does not do strict alignment for COPYING_UNITS.  */
        !           136:       already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
        !           137:     }
        !           138:   else
        !           139:     already = 0;
        !           140:   /* Copy remaining bytes one by one.  */
        !           141:   for (i = already; i < obj_size; i++)
        !           142:     new_chunk->contents[i] = h->object_base[i];
        !           143: 
        !           144:   /* If the object just copied was the only data in OLD_CHUNK,
        !           145:      free that chunk and remove it from the chain.
        !           146:      But not if that chunk might contain an empty object.  */
        !           147:   if (h->object_base == old_chunk->contents && ! h->maybe_empty_object)
        !           148:     {
        !           149:       new_chunk->prev = old_chunk->prev;
        !           150:       (*h->freefun) (old_chunk);
        !           151:     }
        !           152: 
        !           153:   h->object_base = new_chunk->contents;
        !           154:   h->next_free = h->object_base + obj_size;
        !           155:   /* The new chunk certainly contains no empty object yet.  */
        !           156:   h->maybe_empty_object = 0;
        !           157: }
        !           158: 
        !           159: /* Return nonzero if object OBJ has been allocated from obstack H.
        !           160:    This is here for debugging.
        !           161:    If you use it in a program, you are probably losing.  */
        !           162: 
        !           163: int
        !           164: _obstack_allocated_p (h, obj)
        !           165:      struct obstack *h;
        !           166:      POINTER obj;
        !           167: {
        !           168:   register struct _obstack_chunk*  lp; /* below addr of any objects in this chunk */
        !           169:   register struct _obstack_chunk*  plp;        /* point to previous chunk if any */
        !           170: 
        !           171:   lp = (h)->chunk;
        !           172:   /* We use >= rather than > since the object cannot be exactly at
        !           173:      the beginning of the chunk but might be an empty object exactly
        !           174:      at the end of an adjacent chunk. */
        !           175:   while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
        !           176:     {
        !           177:       plp = lp->prev;
        !           178:       lp = plp;
        !           179:     }
        !           180:   return lp != 0;
        !           181: }
        !           182: 
        !           183: /* Free objects in obstack H, including OBJ and everything allocate
        !           184:    more recently than OBJ.  If OBJ is zero, free everything in H.  */
        !           185: 
        !           186: #undef obstack_free
        !           187: 
        !           188: /* This function has two names with identical definitions.
        !           189:    This is the first one, called from non-ANSI code.  */
        !           190: 
        !           191: void
        !           192: _obstack_free (h, obj)
        !           193:      struct obstack *h;
        !           194:      POINTER obj;
        !           195: {
        !           196:   register struct _obstack_chunk*  lp; /* below addr of any objects in this chunk */
        !           197:   register struct _obstack_chunk*  plp;        /* point to previous chunk if any */
        !           198: 
        !           199:   lp = h->chunk;
        !           200:   /* We use >= because there cannot be an object at the beginning of a chunk.
        !           201:      But there can be an empty object at that address
        !           202:      at the end of another chunk.  */
        !           203:   while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
        !           204:     {
        !           205:       plp = lp->prev;
        !           206:       (*h->freefun) (lp);
        !           207:       lp = plp;
        !           208:       /* If we switch chunks, we can't tell whether the new current
        !           209:         chunk contains an empty object, so assume that it may.  */
        !           210:       h->maybe_empty_object = 1;
        !           211:     }
        !           212:   if (lp)
        !           213:     {
        !           214:       h->object_base = h->next_free = (char *)(obj);
        !           215:       h->chunk_limit = lp->limit;
        !           216:       h->chunk = lp;
        !           217:     }
        !           218:   else if (obj != 0)
        !           219:     /* obj is not in any of the chunks! */
        !           220:     abort ();
        !           221: }
        !           222: 
        !           223: /* This function is used from ANSI code.  */
        !           224: 
        !           225: void
        !           226: obstack_free (h, obj)
        !           227:      struct obstack *h;
        !           228:      POINTER obj;
        !           229: {
        !           230:   register struct _obstack_chunk*  lp; /* below addr of any objects in this chunk */
        !           231:   register struct _obstack_chunk*  plp;        /* point to previous chunk if any */
        !           232: 
        !           233:   lp = h->chunk;
        !           234:   /* We use >= because there cannot be an object at the beginning of a chunk.
        !           235:      But there can be an empty object at that address
        !           236:      at the end of another chunk.  */
        !           237:   while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
        !           238:     {
        !           239:       plp = lp->prev;
        !           240:       (*h->freefun) (lp);
        !           241:       lp = plp;
        !           242:       /* If we switch chunks, we can't tell whether the new current
        !           243:         chunk contains an empty object, so assume that it may.  */
        !           244:       h->maybe_empty_object = 1;
        !           245:     }
        !           246:   if (lp)
        !           247:     {
        !           248:       h->object_base = h->next_free = (char *)(obj);
        !           249:       h->chunk_limit = lp->limit;
        !           250:       h->chunk = lp;
        !           251:     }
        !           252:   else if (obj != 0)
        !           253:     /* obj is not in any of the chunks! */
        !           254:     abort ();
        !           255: }
        !           256: 
        !           257: #if 0
        !           258: /* These are now turned off because the applications do not use it
        !           259:    and it uses bcopy via obstack_grow, which causes trouble on sysV.  */
        !           260: 
        !           261: /* Now define the functional versions of the obstack macros.
        !           262:    Define them to simply use the corresponding macros to do the job.  */
        !           263: 
        !           264: #ifdef __STDC__
        !           265: /* These function definitions do not work with non-ANSI preprocessors;
        !           266:    they won't pass through the macro names in parentheses.  */
        !           267: 
        !           268: /* The function names appear in parentheses in order to prevent
        !           269:    the macro-definitions of the names from being expanded there.  */
        !           270: 
        !           271: POINTER (obstack_base) (obstack)
        !           272:      struct obstack *obstack;
        !           273: {
        !           274:   return obstack_base (obstack);
        !           275: }
        !           276: 
        !           277: POINTER (obstack_next_free) (obstack)
        !           278:      struct obstack *obstack;
        !           279: {
        !           280:   return obstack_next_free (obstack);
        !           281: }
        !           282: 
        !           283: int (obstack_object_size) (obstack)
        !           284:      struct obstack *obstack;
        !           285: {
        !           286:   return obstack_object_size (obstack);
        !           287: }
        !           288: 
        !           289: int (obstack_room) (obstack)
        !           290:      struct obstack *obstack;
        !           291: {
        !           292:   return obstack_room (obstack);
        !           293: }
        !           294: 
        !           295: void (obstack_grow) (obstack, pointer, length)
        !           296:      struct obstack *obstack;
        !           297:      POINTER pointer;
        !           298:      int length;
        !           299: {
        !           300:   obstack_grow (obstack, pointer, length);
        !           301: }
        !           302: 
        !           303: void (obstack_grow0) (obstack, pointer, length)
        !           304:      struct obstack *obstack;
        !           305:      POINTER pointer;
        !           306:      int length;
        !           307: {
        !           308:   obstack_grow0 (obstack, pointer, length);
        !           309: }
        !           310: 
        !           311: void (obstack_1grow) (obstack, character)
        !           312:      struct obstack *obstack;
        !           313:      int character;
        !           314: {
        !           315:   obstack_1grow (obstack, character);
        !           316: }
        !           317: 
        !           318: void (obstack_blank) (obstack, length)
        !           319:      struct obstack *obstack;
        !           320:      int length;
        !           321: {
        !           322:   obstack_blank (obstack, length);
        !           323: }
        !           324: 
        !           325: void (obstack_1grow_fast) (obstack, character)
        !           326:      struct obstack *obstack;
        !           327:      int character;
        !           328: {
        !           329:   obstack_1grow_fast (obstack, character);
        !           330: }
        !           331: 
        !           332: void (obstack_blank_fast) (obstack, length)
        !           333:      struct obstack *obstack;
        !           334:      int length;
        !           335: {
        !           336:   obstack_blank_fast (obstack, length);
        !           337: }
        !           338: 
        !           339: POINTER (obstack_finish) (obstack)
        !           340:      struct obstack *obstack;
        !           341: {
        !           342:   return obstack_finish (obstack);
        !           343: }
        !           344: 
        !           345: POINTER (obstack_alloc) (obstack, length)
        !           346:      struct obstack *obstack;
        !           347:      int length;
        !           348: {
        !           349:   return obstack_alloc (obstack, length);
        !           350: }
        !           351: 
        !           352: POINTER (obstack_copy) (obstack, pointer, length)
        !           353:      struct obstack *obstack;
        !           354:      POINTER pointer;
        !           355:      int length;
        !           356: {
        !           357:   return obstack_copy (obstack, pointer, length);
        !           358: }
        !           359: 
        !           360: POINTER (obstack_copy0) (obstack, pointer, length)
        !           361:      struct obstack *obstack;
        !           362:      POINTER pointer;
        !           363:      int length;
        !           364: {
        !           365:   return obstack_copy0 (obstack, pointer, length);
        !           366: }
        !           367: 
        !           368: #endif /* __STDC__ */
        !           369: 
        !           370: #endif /* 0 */

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