| 1 | /* objalloc.h -- routines to allocate memory for objects
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| 2 | Copyright (C) 1997-2021 Free Software Foundation, Inc.
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| 3 | Written by Ian Lance Taylor, Cygnus Solutions.
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| 4 |
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| 5 | This program is free software; you can redistribute it and/or modify it
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| 6 | under the terms of the GNU General Public License as published by the
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| 7 | Free Software Foundation; either version 2, or (at your option) any
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| 8 | later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program; if not, write to the Free Software
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| 17 | Foundation, 51 Franklin Street - Fifth Floor,
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| 18 | Boston, MA 02110-1301, USA. */
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| 19 |
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| 20 | #ifndef OBJALLOC_H
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| 21 | #define OBJALLOC_H
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| 22 |
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| 23 | #include "ansidecl.h"
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| 24 |
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| 25 | /* These routines allocate space for an object. The assumption is
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| 26 | that the object will want to allocate space as it goes along, but
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| 27 | will never want to free any particular block. There is a function
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| 28 | to free a block, which also frees all more recently allocated
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| 29 | blocks. There is also a function to free all the allocated space.
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| 30 |
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| 31 | This is essentially a specialization of obstacks. The main
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| 32 | difference is that a block may not be allocated a bit at a time.
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| 33 | Another difference is that these routines are always built on top
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| 34 | of malloc, and always pass an malloc failure back to the caller,
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| 35 | unlike more recent versions of obstacks. */
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| 36 |
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| 37 | /* This is what an objalloc structure looks like. Callers should not
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| 38 | refer to these fields, nor should they allocate these structure
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| 39 | themselves. Instead, they should only create them via
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| 40 | objalloc_init, and only access them via the functions and macros
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| 41 | listed below. The structure is only defined here so that we can
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| 42 | access it via macros. */
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| 43 |
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| 44 | struct objalloc
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| 45 | {
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| 46 | char *current_ptr;
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| 47 | unsigned int current_space;
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| 48 | void *chunks;
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| 49 | };
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| 50 |
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| 51 | /* Work out the required alignment. */
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| 52 |
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| 53 | struct objalloc_align { char x; double d; };
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| 54 |
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| 55 | #if defined (__STDC__) && __STDC__
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| 56 | #ifndef offsetof
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| 57 | #include <stddef.h>
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| 58 | #endif
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| 59 | #endif
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| 60 | #ifndef offsetof
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| 61 | #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
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| 62 | #endif
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| 63 | #define OBJALLOC_ALIGN offsetof (struct objalloc_align, d)
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| 64 |
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| 65 | /* Create an objalloc structure. Returns NULL if malloc fails. */
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| 66 |
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| 67 | extern struct objalloc *objalloc_create (void);
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| 68 |
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| 69 | /* Allocate space from an objalloc structure. Returns NULL if malloc
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| 70 | fails. */
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| 71 |
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| 72 | extern void *_objalloc_alloc (struct objalloc *, unsigned long);
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| 73 |
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| 74 | /* The macro version of objalloc_alloc. We only define this if using
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| 75 | gcc, because otherwise we would have to evaluate the arguments
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| 76 | multiple times, or use a temporary field as obstack.h does. */
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| 77 |
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| 78 | #if defined (__GNUC__) && defined (__STDC__) && __STDC__
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| 79 |
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| 80 | /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
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| 81 | does not implement __extension__. But that compiler doesn't define
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| 82 | __GNUC_MINOR__. */
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| 83 | #if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
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| 84 | #define __extension__
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| 85 | #endif
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| 86 |
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| 87 | #define objalloc_alloc(o, l) \
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| 88 | __extension__ \
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| 89 | ({ struct objalloc *__o = (o); \
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| 90 | unsigned long __len = (l); \
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| 91 | if (__len == 0) \
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| 92 | __len = 1; \
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| 93 | __len = (__len + OBJALLOC_ALIGN - 1) &~ (OBJALLOC_ALIGN - 1); \
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| 94 | (__len != 0 && __len <= __o->current_space \
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| 95 | ? (__o->current_ptr += __len, \
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| 96 | __o->current_space -= __len, \
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| 97 | (void *) (__o->current_ptr - __len)) \
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| 98 | : _objalloc_alloc (__o, __len)); })
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| 99 |
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| 100 | #else /* ! __GNUC__ */
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| 101 |
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| 102 | #define objalloc_alloc(o, l) _objalloc_alloc ((o), (l))
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| 103 |
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| 104 | #endif /* ! __GNUC__ */
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| 105 |
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| 106 | /* Free an entire objalloc structure. */
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| 107 |
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| 108 | extern void objalloc_free (struct objalloc *);
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| 109 |
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| 110 | /* Free a block allocated by objalloc_alloc. This also frees all more
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| 111 | recently allocated blocks. */
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| 112 |
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| 113 | extern void objalloc_free_block (struct objalloc *, void *);
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| 114 |
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| 115 | #endif /* OBJALLOC_H */
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