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375 lines
11 KiB
C
375 lines
11 KiB
C
/* obstack.c - subroutines used implicitly by object stack macros
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Copyright (C) 1988 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#ifndef lint
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static char rcsid[] = "$Id$";
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#endif
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#include "obstack.h"
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#ifdef __STDC__
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#define POINTER void *
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#else
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#define POINTER char *
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#endif
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/* Determine default alignment. */
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struct fooalign {char x; double d;};
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#define DEFAULT_ALIGNMENT ((char *)&((struct fooalign *) 0)->d - (char *)0)
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/* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
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But in fact it might be less smart and round addresses to as much as
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DEFAULT_ROUNDING. So we prepare for it to do that. */
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union fooround {long x; double d;};
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#define DEFAULT_ROUNDING (sizeof (union fooround))
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/* When we copy a long block of data, this is the unit to do it with.
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On some machines, copying successive ints does not work;
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in such a case, redefine COPYING_UNIT to `long' (if that works)
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or `char' as a last resort. */
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#ifndef COPYING_UNIT
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#define COPYING_UNIT int
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#endif
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/* The non-GNU-C macros copy the obstack into this global variable
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to avoid multiple evaluation. */
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struct obstack *_obstack;
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/* Initialize an obstack H for use. Specify chunk size SIZE (0 means default).
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Objects start on multiples of ALIGNMENT (0 means use default).
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CHUNKFUN is the function to use to allocate chunks,
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and FREEFUN the function to free them. */
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void
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_obstack_begin (h, size, alignment, chunkfun, freefun)
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struct obstack *h;
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int size;
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int alignment;
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POINTER (*chunkfun) ();
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void (*freefun) ();
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{
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register struct _obstack_chunk* chunk; /* points to new chunk */
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if (alignment == 0)
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alignment = DEFAULT_ALIGNMENT;
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if (size == 0)
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/* Default size is what GNU malloc can fit in a 4096-byte block. */
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{
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/* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
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Use the values for range checking, because if range checking is off,
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the extra bytes won't be missed terribly, but if range checking is on
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and we used a larger request, a whole extra 4096 bytes would be
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allocated.
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These number are irrelevant to the new GNU malloc. I suspect it is
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less sensitive to the size of the request. */
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int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
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+ 4 + DEFAULT_ROUNDING - 1)
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& ~(DEFAULT_ROUNDING - 1));
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size = 4096 - extra;
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}
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h->chunkfun = (struct _obstack_chunk * (*)()) chunkfun;
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h->freefun = freefun;
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h->chunk_size = size;
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h->alignment_mask = alignment - 1;
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chunk = h->chunk = (*h->chunkfun) (h->chunk_size);
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h->next_free = h->object_base = chunk->contents;
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h->chunk_limit = chunk->limit
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= (char *) chunk + h->chunk_size;
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chunk->prev = 0;
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/* The initial chunk now contains no empty object. */
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h->maybe_empty_object = 0;
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}
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/* Allocate a new current chunk for the obstack *H
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on the assumption that LENGTH bytes need to be added
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to the current object, or a new object of length LENGTH allocated.
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Copies any partial object from the end of the old chunk
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to the beginning of the new one. */
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void
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_obstack_newchunk (h, length)
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struct obstack *h;
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int length;
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{
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register struct _obstack_chunk* old_chunk = h->chunk;
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register struct _obstack_chunk* new_chunk;
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register long new_size;
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register int obj_size = h->next_free - h->object_base;
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register int i;
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int already;
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/* Compute size for new chunk. */
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new_size = (obj_size + length) + (obj_size >> 3) + 100;
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if (new_size < h->chunk_size)
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new_size = h->chunk_size;
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/* Allocate and initialize the new chunk. */
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new_chunk = h->chunk = (*h->chunkfun) (new_size);
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new_chunk->prev = old_chunk;
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new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
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/* Move the existing object to the new chunk.
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Word at a time is fast and is safe if the object
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is sufficiently aligned. */
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if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
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{
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for (i = obj_size / sizeof (COPYING_UNIT) - 1;
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i >= 0; i--)
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((COPYING_UNIT *)new_chunk->contents)[i]
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= ((COPYING_UNIT *)h->object_base)[i];
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/* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
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but that can cross a page boundary on a machine
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which does not do strict alignment for COPYING_UNITS. */
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already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
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}
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else
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already = 0;
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/* Copy remaining bytes one by one. */
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for (i = already; i < obj_size; i++)
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new_chunk->contents[i] = h->object_base[i];
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/* If the object just copied was the only data in OLD_CHUNK,
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free that chunk and remove it from the chain.
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But not if that chunk might contain an empty object. */
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if (h->object_base == old_chunk->contents && ! h->maybe_empty_object)
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{
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new_chunk->prev = old_chunk->prev;
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(*h->freefun) (old_chunk);
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}
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h->object_base = new_chunk->contents;
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h->next_free = h->object_base + obj_size;
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/* The new chunk certainly contains no empty object yet. */
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h->maybe_empty_object = 0;
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}
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/* Return nonzero if object OBJ has been allocated from obstack H.
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This is here for debugging.
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If you use it in a program, you are probably losing. */
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int
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_obstack_allocated_p (h, obj)
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struct obstack *h;
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POINTER obj;
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{
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register struct _obstack_chunk* lp; /* below addr of any objects in this chunk */
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register struct _obstack_chunk* plp; /* point to previous chunk if any */
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lp = (h)->chunk;
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/* We use >= rather than > since the object cannot be exactly at
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the beginning of the chunk but might be an empty object exactly
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at the end of an adjacent chunk. */
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while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
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{
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plp = lp->prev;
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lp = plp;
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}
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return lp != 0;
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}
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/* Free objects in obstack H, including OBJ and everything allocate
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more recently than OBJ. If OBJ is zero, free everything in H. */
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#undef obstack_free
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/* This function has two names with identical definitions.
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This is the first one, called from non-ANSI code. */
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void
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_obstack_free (h, obj)
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struct obstack *h;
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POINTER obj;
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{
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register struct _obstack_chunk* lp; /* below addr of any objects in this chunk */
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register struct _obstack_chunk* plp; /* point to previous chunk if any */
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lp = h->chunk;
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/* We use >= because there cannot be an object at the beginning of a chunk.
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But there can be an empty object at that address
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at the end of another chunk. */
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while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
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{
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plp = lp->prev;
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(*h->freefun) (lp);
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lp = plp;
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/* If we switch chunks, we can't tell whether the new current
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chunk contains an empty object, so assume that it may. */
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h->maybe_empty_object = 1;
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}
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if (lp)
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{
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h->object_base = h->next_free = (char *)(obj);
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h->chunk_limit = lp->limit;
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h->chunk = lp;
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}
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else if (obj != 0)
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/* obj is not in any of the chunks! */
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abort ();
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}
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/* This function is used from ANSI code. */
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void
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obstack_free (h, obj)
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struct obstack *h;
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POINTER obj;
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{
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register struct _obstack_chunk* lp; /* below addr of any objects in this chunk */
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register struct _obstack_chunk* plp; /* point to previous chunk if any */
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lp = h->chunk;
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/* We use >= because there cannot be an object at the beginning of a chunk.
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But there can be an empty object at that address
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at the end of another chunk. */
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while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
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{
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plp = lp->prev;
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(*h->freefun) (lp);
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lp = plp;
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/* If we switch chunks, we can't tell whether the new current
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chunk contains an empty object, so assume that it may. */
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h->maybe_empty_object = 1;
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}
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if (lp)
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{
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h->object_base = h->next_free = (char *)(obj);
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h->chunk_limit = lp->limit;
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h->chunk = lp;
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}
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else if (obj != 0)
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/* obj is not in any of the chunks! */
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abort ();
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}
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#if 0
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/* These are now turned off because the applications do not use it
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and it uses bcopy via obstack_grow, which causes trouble on sysV. */
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/* Now define the functional versions of the obstack macros.
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Define them to simply use the corresponding macros to do the job. */
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#ifdef __STDC__
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/* These function definitions do not work with non-ANSI preprocessors;
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they won't pass through the macro names in parentheses. */
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/* The function names appear in parentheses in order to prevent
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the macro-definitions of the names from being expanded there. */
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POINTER (obstack_base) (obstack)
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struct obstack *obstack;
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{
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return obstack_base (obstack);
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}
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POINTER (obstack_next_free) (obstack)
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struct obstack *obstack;
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{
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return obstack_next_free (obstack);
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}
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int (obstack_object_size) (obstack)
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struct obstack *obstack;
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{
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return obstack_object_size (obstack);
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}
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int (obstack_room) (obstack)
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struct obstack *obstack;
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{
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return obstack_room (obstack);
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}
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void (obstack_grow) (obstack, pointer, length)
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struct obstack *obstack;
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POINTER pointer;
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int length;
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{
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obstack_grow (obstack, pointer, length);
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}
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void (obstack_grow0) (obstack, pointer, length)
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struct obstack *obstack;
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POINTER pointer;
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int length;
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{
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obstack_grow0 (obstack, pointer, length);
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}
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void (obstack_1grow) (obstack, character)
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struct obstack *obstack;
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int character;
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{
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obstack_1grow (obstack, character);
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}
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void (obstack_blank) (obstack, length)
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struct obstack *obstack;
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int length;
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{
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obstack_blank (obstack, length);
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}
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void (obstack_1grow_fast) (obstack, character)
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struct obstack *obstack;
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int character;
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{
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obstack_1grow_fast (obstack, character);
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}
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void (obstack_blank_fast) (obstack, length)
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struct obstack *obstack;
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int length;
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{
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obstack_blank_fast (obstack, length);
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}
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POINTER (obstack_finish) (obstack)
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struct obstack *obstack;
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{
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return obstack_finish (obstack);
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}
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POINTER (obstack_alloc) (obstack, length)
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struct obstack *obstack;
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int length;
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{
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return obstack_alloc (obstack, length);
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}
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POINTER (obstack_copy) (obstack, pointer, length)
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struct obstack *obstack;
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POINTER pointer;
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int length;
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{
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return obstack_copy (obstack, pointer, length);
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}
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POINTER (obstack_copy0) (obstack, pointer, length)
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struct obstack *obstack;
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POINTER pointer;
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int length;
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{
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return obstack_copy0 (obstack, pointer, length);
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}
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#endif /* __STDC__ */
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#endif /* 0 */
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