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comparison include/objalloc.h @ 0:a06113de4d67

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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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1 /* objalloc.h -- routines to allocate memory for objects
2 Copyright 1997, 2001 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Cygnus Solutions.
4
5 This program is free software; you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published by the
7 Free Software Foundation; either version 2, or (at your option) any
8 later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, 51 Franklin Street - Fifth Floor,
18 Boston, MA 02110-1301, USA. */
19
20 #ifndef OBJALLOC_H
21 #define OBJALLOC_H
22
23 #include "ansidecl.h"
24
25 /* These routines allocate space for an object. The assumption is
26 that the object will want to allocate space as it goes along, but
27 will never want to free any particular block. There is a function
28 to free a block, which also frees all more recently allocated
29 blocks. There is also a function to free all the allocated space.
30
31 This is essentially a specialization of obstacks. The main
32 difference is that a block may not be allocated a bit at a time.
33 Another difference is that these routines are always built on top
34 of malloc, and always pass an malloc failure back to the caller,
35 unlike more recent versions of obstacks. */
36
37 /* This is what an objalloc structure looks like. Callers should not
38 refer to these fields, nor should they allocate these structure
39 themselves. Instead, they should only create them via
40 objalloc_init, and only access them via the functions and macros
41 listed below. The structure is only defined here so that we can
42 access it via macros. */
43
44 struct objalloc
45 {
46 char *current_ptr;
47 unsigned int current_space;
48 void *chunks;
49 };
50
51 /* Work out the required alignment. */
52
53 struct objalloc_align { char x; double d; };
54
55 #if defined (__STDC__) && __STDC__
56 #ifndef offsetof
57 #include <stddef.h>
58 #endif
59 #endif
60 #ifndef offsetof
61 #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
62 #endif
63 #define OBJALLOC_ALIGN offsetof (struct objalloc_align, d)
64
65 /* Create an objalloc structure. Returns NULL if malloc fails. */
66
67 extern struct objalloc *objalloc_create (void);
68
69 /* Allocate space from an objalloc structure. Returns NULL if malloc
70 fails. */
71
72 extern void *_objalloc_alloc (struct objalloc *, unsigned long);
73
74 /* The macro version of objalloc_alloc. We only define this if using
75 gcc, because otherwise we would have to evaluate the arguments
76 multiple times, or use a temporary field as obstack.h does. */
77
78 #if defined (__GNUC__) && defined (__STDC__) && __STDC__
79
80 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
81 does not implement __extension__. But that compiler doesn't define
82 __GNUC_MINOR__. */
83 #if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
84 #define __extension__
85 #endif
86
87 #define objalloc_alloc(o, l) \
88 __extension__ \
89 ({ struct objalloc *__o = (o); \
90 unsigned long __len = (l); \
91 if (__len == 0) \
92 __len = 1; \
93 __len = (__len + OBJALLOC_ALIGN - 1) &~ (OBJALLOC_ALIGN - 1); \
94 (__len <= __o->current_space \
95 ? (__o->current_ptr += __len, \
96 __o->current_space -= __len, \
97 (void *) (__o->current_ptr - __len)) \
98 : _objalloc_alloc (__o, __len)); })
99
100 #else /* ! __GNUC__ */
101
102 #define objalloc_alloc(o, l) _objalloc_alloc ((o), (l))
103
104 #endif /* ! __GNUC__ */
105
106 /* Free an entire objalloc structure. */
107
108 extern void objalloc_free (struct objalloc *);
109
110 /* Free a block allocated by objalloc_alloc. This also frees all more
111 recently allocated blocks. */
112
113 extern void objalloc_free_block (struct objalloc *, void *);
114
115 #endif /* OBJALLOC_H */