src/lua/lmem.c

   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