/*

** $Id: lmem.c,v 1.70.1.1 2007/12/27 13:02:25 roberto Exp $

** Interface to Memory Manager

** See Copyright Notice in lua.h

*/

#include <stddef.h>

#define lmem_c

#define LUA_CORE

#include "lua.h"

#include "ldebug.h"

#include "ldo.h"

#include "lmem.h"

#include "lobject.h"

#include "lstate.h"

/*

** About the realloc function:

** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);

** (`osize' is the old size, `nsize' is the new size)

**

** Lua ensures that (ptr == NULL) iff (osize == 0).

**

** * frealloc(ud, NULL, 0, x) creates a new block of size `x'

**

** * frealloc(ud, p, x, 0) frees the block `p'

** (in this specific case, frealloc must return NULL).

** particularly, frealloc(ud, NULL, 0, 0) does nothing

** (which is equivalent to free(NULL) in ANSI C)

**

** frealloc returns NULL if it cannot create or reallocate the area

** (any reallocation to an equal or smaller size cannot fail!)

*/

#define MINSIZEARRAY    4

void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,

                     int limit, const char *errormsg) {

  void *newblock;

  int newsize;

  if (*size >= limit/2) {  /* cannot double it? */

    if (*size >= limit)  /* cannot grow even a little? */

      luaG_runerror(L, errormsg);

    newsize = limit;  /* still have at least one free place */

  }

  else {

    newsize = (*size)*2;

    if (newsize < MINSIZEARRAY)

      newsize = MINSIZEARRAY;  /* minimum size */

  }

  newblock = luaM_reallocv(L, block, *size, newsize, size_elems);

  *size = newsize;  /* update only when everything else is OK */

  return newblock;

}

void *luaM_toobig (lua_State *L) {

  luaG_runerror(L, "memory allocation error: block too big");

  return NULL;  /* to avoid warnings */

}

/*

** generic allocation routine.

*/

void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {

  global_State *g = G(L);

  lua_assert((osize == 0) == (block == NULL));

  block = (*g->frealloc)(g->ud, block, osize, nsize);

  if (block == NULL && nsize > 0)

    luaD_throw(L, LUA_ERRMEM);

  lua_assert((nsize == 0) == (block == NULL));

  g->totalbytes = (g->totalbytes - osize) + nsize;

  return block;

}