| 1 | /* objalloc.h -- routines to allocate memory for objects |
| 2 | Copyright (C) 1997-2017 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 */ |