116 lines
3.9 KiB
C
116 lines
3.9 KiB
C
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/* objalloc.h -- routines to allocate memory for objects
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Copyright 1997 Free Software Foundation, Inc.
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Written by Ian Lance Taylor, Cygnus Solutions.
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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 OBJALLOC_H
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#define OBJALLOC_H
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#include "ansidecl.h"
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/* These routines allocate space for an object. The assumption is
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that the object will want to allocate space as it goes along, but
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will never want to free any particular block. There is a function
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to free a block, which also frees all more recently allocated
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blocks. There is also a function to free all the allocated space.
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This is essentially a specialization of obstacks. The main
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difference is that a block may not be allocated a bit at a time.
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Another difference is that these routines are always built on top
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of malloc, and always pass an malloc failure back to the caller,
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unlike more recent versions of obstacks. */
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/* This is what an objalloc structure looks like. Callers should not
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refer to these fields, nor should they allocate these structure
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themselves. Instead, they should only create them via
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objalloc_init, and only access them via the functions and macros
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listed below. The structure is only defined here so that we can
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access it via macros. */
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struct objalloc
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{
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char *current_ptr;
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unsigned int current_space;
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PTR chunks;
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};
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/* Work out the required alignment. */
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struct objalloc_align { char x; double d; };
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#if defined (__STDC__) && __STDC__
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#ifndef offsetof
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#include <stddef.h>
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#endif
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#define OBJALLOC_ALIGN \
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((ptrdiff_t) ((char *) &((struct objalloc_align *) 0)->d - (char *) 0))
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#else
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#define OBJALLOC_ALIGN \
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((long) ((char *) &((struct objalloc_align *) 0)->d - (char *) 0))
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#endif
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/* Create an objalloc structure. Returns NULL if malloc fails. */
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extern struct objalloc *objalloc_create PARAMS ((void));
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/* Allocate space from an objalloc structure. Returns NULL if malloc
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fails. */
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extern PTR _objalloc_alloc PARAMS ((struct objalloc *, unsigned long));
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/* The macro version of objalloc_alloc. We only define this if using
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gcc, because otherwise we would have to evaluate the arguments
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multiple times, or use a temporary field as obstack.h does. */
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#if defined (__GNUC__) && defined (__STDC__) && __STDC__
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/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
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does not implement __extension__. But that compiler doesn't define
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__GNUC_MINOR__. */
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#if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
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#define __extension__
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#endif
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#define objalloc_alloc(o, l) \
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__extension__ \
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({ struct objalloc *__o = (o); \
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unsigned long __len = (l); \
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if (__len == 0) \
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__len = 1; \
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__len = (__len + OBJALLOC_ALIGN - 1) &~ (OBJALLOC_ALIGN - 1); \
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(__len <= __o->current_space \
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? (__o->current_ptr += __len, \
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__o->current_space -= __len, \
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(PTR) (__o->current_ptr - __len)) \
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: _objalloc_alloc (__o, __len)); })
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#else /* ! __GNUC__ */
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#define objalloc_alloc(o, l) _objalloc_alloc ((o), (l))
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#endif /* ! __GNUC__ */
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/* Free an entire objalloc structure. */
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extern void objalloc_free PARAMS ((struct objalloc *));
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/* Free a block allocated by objalloc_alloc. This also frees all more
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recently allocated blocks. */
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extern void objalloc_free_block PARAMS ((struct objalloc *, PTR));
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#endif /* OBJALLOC_H */
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