/*
** $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;
}
