Lua 5.1.4: lmem.c

L0001    /*
L0002    ** $Id: lmem.c,v 1.70.1.1 2007/12/27 13:02:25 roberto Exp $
L0003    ** Interface to Memory Manager
L0004    ** See Copyright Notice in lua.h
L0005    */
L0006    
L0007    
L0008    #include <stddef.h>
L0009    
L0010    #define lmem_c
L0011    #define LUA_CORE
L0012    
L0013    #include "lua.h"
L0014    
L0015    #include "ldebug.h"
L0016    #include "ldo.h"
L0017    #include "lmem.h"
L0018    #include "lobject.h"
L0019    #include "lstate.h"
L0020    
L0021    
L0022    
L0023    /*
L0024    ** About the realloc function:
L0025    ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
L0026    ** (`osize' is the old size, `nsize' is the new size)
L0027    **
L0028    ** Lua ensures that (ptr == NULL) iff (osize == 0).
L0029    **
L0030    ** * frealloc(ud, NULL, 0, x) creates a new block of size `x'
L0031    **
L0032    ** * frealloc(ud, p, x, 0) frees the block `p'
L0033    ** (in this specific case, frealloc must return NULL).
L0034    ** particularly, frealloc(ud, NULL, 0, 0) does nothing
L0035    ** (which is equivalent to free(NULL) in ANSI C)
L0036    **
L0037    ** frealloc returns NULL if it cannot create or reallocate the area
L0038    ** (any reallocation to an equal or smaller size cannot fail!)
L0039    */
L0040    
L0041    
L0042    
L0043    #define MINSIZEARRAY	4
L0044    
L0045    
L0046    void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
L0047                         int limit, const char *errormsg) {
L0048      void *newblock;
L0049      int newsize;
L0050      if (*size >= limit/2) {  /* cannot double it? */
L0051        if (*size >= limit)  /* cannot grow even a little? */
L0052          luaG_runerror(L, errormsg);
L0053        newsize = limit;  /* still have at least one free place */
L0054      }
L0055      else {
L0056        newsize = (*size)*2;
L0057        if (newsize < MINSIZEARRAY)
L0058          newsize = MINSIZEARRAY;  /* minimum size */
L0059      }
L0060      newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
L0061      *size = newsize;  /* update only when everything else is OK */
L0062      return newblock;
L0063    }
L0064    
L0065    
L0066    void *luaM_toobig (lua_State *L) {
L0067      luaG_runerror(L, "memory allocation error: block too big");
L0068      return NULL;  /* to avoid warnings */
L0069    }
L0070    
L0071    
L0072    
L0073    /*
L0074    ** generic allocation routine.
L0075    */
L0076    void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
L0077      global_State *g = G(L);
L0078      lua_assert((osize == 0) == (block == NULL));
L0079      block = (*g->frealloc)(g->ud, block, osize, nsize);
L0080      if (block == NULL && nsize > 0)
L0081        luaD_throw(L, LUA_ERRMEM);
L0082      lua_assert((nsize == 0) == (block == NULL));
L0083      g->totalbytes = (g->totalbytes - osize) + nsize;
L0084      return block;
L0085    }
L0086