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Root/lua/lmem.cc

1/*
2** $Id: lmem.c,v 1.70 2005/12/26 13:35:47 roberto Exp $
3** Interface to Memory Manager
4** See Copyright Notice in lua.h
5*/
6
7
8#include <stddef.h>
9
10#define lmem_c
11#define LUA_CORE
12
13#include "lua.h"
14
15#include "ldebug.h"
16#include "ldo.h"
17#include "lmem.h"
18#include "lobject.h"
19#include "lstate.h"
20
21
22
23/*
24** About the realloc function:
25** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
26** (`osize' is the old size, `nsize' is the new size)
27**
28** Lua ensures that (ptr == NULL) iff (osize == 0).
29**
30** * frealloc(ud, NULL, 0, x) creates a new block of size `x'
31**
32** * frealloc(ud, p, x, 0) frees the block `p'
33** (in this specific case, frealloc must return NULL).
34** particularly, frealloc(ud, NULL, 0, 0) does nothing
35** (which is equivalent to free(NULL) in ANSI C)
36**
37** frealloc returns NULL if it cannot create or reallocate the area
38** (any reallocation to an equal or smaller size cannot fail!)
39*/
40
41
42
43#define MINSIZEARRAY4
44
45
46void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
47 int limit, const char *errormsg) {
48 void *newblock;
49 int newsize;
50 if (*size >= limit/2) { /* cannot double it? */
51 if (*size >= limit) /* cannot grow even a little? */
52 luaG_runerror(L, errormsg);
53 newsize = limit; /* still have at least one free place */
54 }
55 else {
56 newsize = (*size)*2;
57 if (newsize < MINSIZEARRAY)
58 newsize = MINSIZEARRAY; /* minimum size */
59 }
60 newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
61 *size = newsize; /* update only when everything else is OK */
62 return newblock;
63}
64
65
66void *luaM_toobig (lua_State *L) {
67 luaG_runerror(L, "memory allocation error: block too big");
68 return NULL; /* to avoid warnings */
69}
70
71
72
73/*
74** generic allocation routine.
75*/
76void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
77 global_State *g = G(L);
78 lua_assert((osize == 0) == (block == NULL));
79 block = (*g->frealloc)(g->ud, block, osize, nsize);
80 if (block == NULL && nsize > 0)
81 luaD_throw(L, LUA_ERRMEM);
82 lua_assert((nsize == 0) == (block == NULL));
83 g->totalbytes = (g->totalbytes - osize) + nsize;
84 return block;
85}
86

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