xref: /openbsd-src/gnu/gcc/include/objalloc.h (revision 404b540a9034ac75a6199ad1a32d1bbc7a0d4210)
1*404b540aSrobert /* objalloc.h -- routines to allocate memory for objects
2*404b540aSrobert    Copyright 1997, 2001 Free Software Foundation, Inc.
3*404b540aSrobert    Written by Ian Lance Taylor, Cygnus Solutions.
4*404b540aSrobert 
5*404b540aSrobert This program is free software; you can redistribute it and/or modify it
6*404b540aSrobert under the terms of the GNU General Public License as published by the
7*404b540aSrobert Free Software Foundation; either version 2, or (at your option) any
8*404b540aSrobert later version.
9*404b540aSrobert 
10*404b540aSrobert This program is distributed in the hope that it will be useful,
11*404b540aSrobert but WITHOUT ANY WARRANTY; without even the implied warranty of
12*404b540aSrobert MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13*404b540aSrobert GNU General Public License for more details.
14*404b540aSrobert 
15*404b540aSrobert You should have received a copy of the GNU General Public License
16*404b540aSrobert along with this program; if not, write to the Free Software
17*404b540aSrobert Foundation, 51 Franklin Street - Fifth Floor,
18*404b540aSrobert Boston, MA 02110-1301, USA.  */
19*404b540aSrobert 
20*404b540aSrobert #ifndef OBJALLOC_H
21*404b540aSrobert #define OBJALLOC_H
22*404b540aSrobert 
23*404b540aSrobert #include "ansidecl.h"
24*404b540aSrobert 
25*404b540aSrobert /* These routines allocate space for an object.  The assumption is
26*404b540aSrobert    that the object will want to allocate space as it goes along, but
27*404b540aSrobert    will never want to free any particular block.  There is a function
28*404b540aSrobert    to free a block, which also frees all more recently allocated
29*404b540aSrobert    blocks.  There is also a function to free all the allocated space.
30*404b540aSrobert 
31*404b540aSrobert    This is essentially a specialization of obstacks.  The main
32*404b540aSrobert    difference is that a block may not be allocated a bit at a time.
33*404b540aSrobert    Another difference is that these routines are always built on top
34*404b540aSrobert    of malloc, and always pass an malloc failure back to the caller,
35*404b540aSrobert    unlike more recent versions of obstacks.  */
36*404b540aSrobert 
37*404b540aSrobert /* This is what an objalloc structure looks like.  Callers should not
38*404b540aSrobert    refer to these fields, nor should they allocate these structure
39*404b540aSrobert    themselves.  Instead, they should only create them via
40*404b540aSrobert    objalloc_init, and only access them via the functions and macros
41*404b540aSrobert    listed below.  The structure is only defined here so that we can
42*404b540aSrobert    access it via macros.  */
43*404b540aSrobert 
44*404b540aSrobert struct objalloc
45*404b540aSrobert {
46*404b540aSrobert   char *current_ptr;
47*404b540aSrobert   unsigned int current_space;
48*404b540aSrobert   void *chunks;
49*404b540aSrobert };
50*404b540aSrobert 
51*404b540aSrobert /* Work out the required alignment.  */
52*404b540aSrobert 
53*404b540aSrobert struct objalloc_align { char x; double d; };
54*404b540aSrobert 
55*404b540aSrobert #if defined (__STDC__) && __STDC__
56*404b540aSrobert #ifndef offsetof
57*404b540aSrobert #include <stddef.h>
58*404b540aSrobert #endif
59*404b540aSrobert #endif
60*404b540aSrobert #ifndef offsetof
61*404b540aSrobert #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
62*404b540aSrobert #endif
63*404b540aSrobert #define OBJALLOC_ALIGN offsetof (struct objalloc_align, d)
64*404b540aSrobert 
65*404b540aSrobert /* Create an objalloc structure.  Returns NULL if malloc fails.  */
66*404b540aSrobert 
67*404b540aSrobert extern struct objalloc *objalloc_create (void);
68*404b540aSrobert 
69*404b540aSrobert /* Allocate space from an objalloc structure.  Returns NULL if malloc
70*404b540aSrobert    fails.  */
71*404b540aSrobert 
72*404b540aSrobert extern void *_objalloc_alloc (struct objalloc *, unsigned long);
73*404b540aSrobert 
74*404b540aSrobert /* The macro version of objalloc_alloc.  We only define this if using
75*404b540aSrobert    gcc, because otherwise we would have to evaluate the arguments
76*404b540aSrobert    multiple times, or use a temporary field as obstack.h does.  */
77*404b540aSrobert 
78*404b540aSrobert #if defined (__GNUC__) && defined (__STDC__) && __STDC__
79*404b540aSrobert 
80*404b540aSrobert /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
81*404b540aSrobert    does not implement __extension__.  But that compiler doesn't define
82*404b540aSrobert    __GNUC_MINOR__.  */
83*404b540aSrobert #if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
84*404b540aSrobert #define __extension__
85*404b540aSrobert #endif
86*404b540aSrobert 
87*404b540aSrobert #define objalloc_alloc(o, l)						\
88*404b540aSrobert   __extension__								\
89*404b540aSrobert   ({ struct objalloc *__o = (o);					\
90*404b540aSrobert      unsigned long __len = (l);						\
91*404b540aSrobert      if (__len == 0)							\
92*404b540aSrobert        __len = 1;							\
93*404b540aSrobert      __len = (__len + OBJALLOC_ALIGN - 1) &~ (OBJALLOC_ALIGN - 1);	\
94*404b540aSrobert      (__len <= __o->current_space					\
95*404b540aSrobert       ? (__o->current_ptr += __len,					\
96*404b540aSrobert 	 __o->current_space -= __len,					\
97*404b540aSrobert 	 (void *) (__o->current_ptr - __len))				\
98*404b540aSrobert       : _objalloc_alloc (__o, __len)); })
99*404b540aSrobert 
100*404b540aSrobert #else /* ! __GNUC__ */
101*404b540aSrobert 
102*404b540aSrobert #define objalloc_alloc(o, l) _objalloc_alloc ((o), (l))
103*404b540aSrobert 
104*404b540aSrobert #endif /* ! __GNUC__ */
105*404b540aSrobert 
106*404b540aSrobert /* Free an entire objalloc structure.  */
107*404b540aSrobert 
108*404b540aSrobert extern void objalloc_free (struct objalloc *);
109*404b540aSrobert 
110*404b540aSrobert /* Free a block allocated by objalloc_alloc.  This also frees all more
111*404b540aSrobert    recently allocated blocks.  */
112*404b540aSrobert 
113*404b540aSrobert extern void objalloc_free_block (struct objalloc *, void *);
114*404b540aSrobert 
115*404b540aSrobert #endif /* OBJALLOC_H */
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