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# lua/lmem.c

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    00001 /*
    00002 ** $Id: lmem.c,v 1.70 2005/12/26 13:35:47 roberto Exp $
    00003 ** Interface to Memory Manager
    00004 ** See Copyright Notice in lua.h
    00005 */
    00006
    00007
    00008 #include <stddef.h>
    00009
    00010 #define lmem_c
    00011 #define LUA_CORE
    00012
    00013 #include "lua.h"
    00014
    00015 #include "ldebug.h"
    00016 #include "ldo.h"
    00017 #include "lmem.h"
    00018 #include "lobject.h"
    00019 #include "lstate.h"
    00020
    00021
    00022
    00023 /*
    00024 ** About the realloc function:
    00025 ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
    00026 ** (`osize' is the old size, `nsize' is the new size)
    00027 **
    00028 ** Lua ensures that (ptr == NULL) iff (osize == 0).
    00029 **
    00030 ** * frealloc(ud, NULL, 0, x) creates a new block of size `x'
    00031 **
    00032 ** * frealloc(ud, p, x, 0) frees the block `p'
    00033 ** (in this specific case, frealloc must return NULL).
    00034 ** particularly, frealloc(ud, NULL, 0, 0) does nothing
    00035 ** (which is equivalent to free(NULL) in ANSI C)
    00036 **
    00037 ** frealloc returns NULL if it cannot create or reallocate the area
    00038 ** (any reallocation to an equal or smaller size cannot fail!)
    00039 */
    00040
    00041
    00042
    00043 #define MINSIZEARRAY    4
    00044
    00045
    00046 void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
    00047                      int limit, const char *errormsg) {
    00048   void *newblock;
    00049   int newsize;
    00050   if (*size >= limit/2) {  /* cannot double it? */
    00051     if (*size >= limit)  /* cannot grow even a little? */
    00052       luaG_runerror(L, errormsg);
    00053     newsize = limit;  /* still have at least one free place */
    00054   }
    00055   else {
    00056     newsize = (*size)*2;
    00057     if (newsize < MINSIZEARRAY)
    00058       newsize = MINSIZEARRAY;  /* minimum size */
    00059   }
    00060   newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
    00061   *size = newsize;  /* update only when everything else is OK */
    00062   return newblock;
    00063 }
    00064
    00065
    00066 void *luaM_toobig (lua_State *L) {
    00067   luaG_runerror(L, "memory allocation error: block too big");
    00068   return NULL;  /* to avoid warnings */
    00069 }
    00070
    00071
    00072
    00073 /*
    00074 ** generic allocation routine.
    00075 */
    00076 void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
    00077   global_State *g = G(L);
    00078   lua_assert((osize == 0) == (block == NULL));
    00079   block = (*g->frealloc)(g->ud, block, osize, nsize);
    00080   if (block == NULL && nsize > 0)
    00081     luaD_throw(L, LUA_ERRMEM);
    00082   lua_assert((nsize == 0) == (block == NULL));
    00083   g->totalbytes = (g->totalbytes - osize) + nsize;
    00084   return block;
    00085 }
    00086