1 /* 2 ** $Id: lmem.c,v 1.70.1.1 2007/12/27 13:02:25 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 MINSIZEARRAY 4 44 45 46 void *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 66 void *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 */ 76 void *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 87