external/mit/lua/dist/src/lmem.c

   1 /*      $NetBSD: lmem.c,v 1.1.1.2 2012/03/15 00:08:07 alnsn Exp $       */
   2
   3 /*
   4 ** $Id: lmem.c,v 1.1.1.2 2012/03/15 00:08:07 alnsn Exp $
   5 ** Interface to Memory Manager
   6 ** See Copyright Notice in lua.h
   7 */
   8
   9
  10 #include <stddef.h>
  11
  12 #define lmem_c
  13 #define LUA_CORE
  14
  15 #include "lua.h"
  16
  17 #include "ldebug.h"
  18 #include "ldo.h"
  19 #include "lmem.h"
  20 #include "lobject.h"
  21 #include "lstate.h"
  22
  23
  24
  25 /*
  26 ** About the realloc function:
  27 ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
  28 ** (`osize' is the old size, `nsize' is the new size)
  29 **
  30 ** Lua ensures that (ptr == NULL) iff (osize == 0).
  31 **
  32 ** * frealloc(ud, NULL, 0, x) creates a new block of size `x'
  33 **
  34 ** * frealloc(ud, p, x, 0) frees the block `p'
  35 ** (in this specific case, frealloc must return NULL).
  36 ** particularly, frealloc(ud, NULL, 0, 0) does nothing
  37 ** (which is equivalent to free(NULL) in ANSI C)
  38 **
  39 ** frealloc returns NULL if it cannot create or reallocate the area
  40 ** (any reallocation to an equal or smaller size cannot fail!)
  41 */
  42
  43
  44
  45 #define MINSIZEARRAY    4
  46
  47
  48 void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
  49                      int limit, const char *errormsg) {
  50   void *newblock;
  51   int newsize;
  52   if (*size >= limit/2) {  /* cannot double it? */
  53     if (*size >= limit)  /* cannot grow even a little? */
  54       luaG_runerror(L, errormsg);
  55     newsize = limit;  /* still have at least one free place */
  56   }
  57   else {
  58     newsize = (*size)*2;
  59     if (newsize < MINSIZEARRAY)
  60       newsize = MINSIZEARRAY;  /* minimum size */
  61   }
  62   newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
  63   *size = newsize;  /* update only when everything else is OK */
  64   return newblock;
  65 }
  66
  67
  68 void *luaM_toobig (lua_State *L) {
  69   luaG_runerror(L, "memory allocation error: block too big");
  70   return NULL;  /* to avoid warnings */
  71 }
  72
  73
  74
  75 /*
  76 ** generic allocation routine.
  77 */
  78 void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
  79   global_State *g = G(L);
  80   lua_assert((osize == 0) == (block == NULL));
  81   block = (*g->frealloc)(g->ud, block, osize, nsize);
  82   if (block == NULL && nsize > 0)
  83     luaD_throw(L, LUA_ERRMEM);
  84   lua_assert((nsize == 0) == (block == NULL));
  85   g->totalbytes = (g->totalbytes - osize) + nsize;
  86   return block;
  87 }
  88