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  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.  
  87.