1 /* objalloc.h -- routines to allocate memory for objects 2 Copyright 1997-2012 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 != 0 && __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 */ 116
