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  1. /*
  2. ** $Id: lmem.h $
  3. ** Interface to Memory Manager
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7. #ifndef lmem_h
  8. #define lmem_h
  9.  
  10.  
  11. #include <stddef.h>
  12.  
  13. #include "llimits.h"
  14. #include "lua.h"
  15.  
  16.  
  17. #define luaM_error(L)   luaD_throw(L, LUA_ERRMEM)
  18.  
  19.  
  20. /*
  21. ** This macro tests whether it is safe to multiply 'n' by the size of
  22. ** type 't' without overflows. Because 'e' is always constant, it avoids
  23. ** the runtime division MAX_SIZET/(e).
  24. ** (The macro is somewhat complex to avoid warnings:  The 'sizeof'
  25. ** comparison avoids a runtime comparison when overflow cannot occur.
  26. ** The compiler should be able to optimize the real test by itself, but
  27. ** when it does it, it may give a warning about "comparison is always
  28. ** false due to limited range of data type"; the +1 tricks the compiler,
  29. ** avoiding this warning but also this optimization.)
  30. */
  31. #define luaM_testsize(n,e)  \
  32.         (sizeof(n) >= sizeof(size_t) && cast_sizet((n)) + 1 > MAX_SIZET/(e))
  33.  
  34. #define luaM_checksize(L,n,e)  \
  35.         (luaM_testsize(n,e) ? luaM_toobig(L) : cast_void(0))
  36.  
  37.  
  38. /*
  39. ** Computes the minimum between 'n' and 'MAX_SIZET/sizeof(t)', so that
  40. ** the result is not larger than 'n' and cannot overflow a 'size_t'
  41. ** when multiplied by the size of type 't'. (Assumes that 'n' is an
  42. ** 'int' or 'unsigned int' and that 'int' is not larger than 'size_t'.)
  43. */
  44. #define luaM_limitN(n,t)  \
  45.   ((cast_sizet(n) <= MAX_SIZET/sizeof(t)) ? (n) :  \
  46.      cast_uint((MAX_SIZET/sizeof(t))))
  47.  
  48.  
  49. /*
  50. ** Arrays of chars do not need any test
  51. */
  52. #define luaM_reallocvchar(L,b,on,n)  \
  53.   cast_charp(luaM_saferealloc_(L, (b), (on)*sizeof(char), (n)*sizeof(char)))
  54.  
  55. #define luaM_freemem(L, b, s)   luaM_free_(L, (b), (s))
  56. #define luaM_free(L, b)         luaM_free_(L, (b), sizeof(*(b)))
  57. #define luaM_freearray(L, b, n)   luaM_free_(L, (b), (n)*sizeof(*(b)))
  58.  
  59. #define luaM_new(L,t)           cast(t*, luaM_malloc_(L, sizeof(t), 0))
  60. #define luaM_newvector(L,n,t)   cast(t*, luaM_malloc_(L, (n)*sizeof(t), 0))
  61. #define luaM_newvectorchecked(L,n,t) \
  62.   (luaM_checksize(L,n,sizeof(t)), luaM_newvector(L,n,t))
  63.  
  64. #define luaM_newobject(L,tag,s) luaM_malloc_(L, (s), tag)
  65.  
  66. #define luaM_growvector(L,v,nelems,size,t,limit,e) \
  67.         ((v)=cast(t *, luaM_growaux_(L,v,nelems,&(size),sizeof(t), \
  68.                          luaM_limitN(limit,t),e)))
  69.  
  70. #define luaM_reallocvector(L, v,oldn,n,t) \
  71.    (cast(t *, luaM_realloc_(L, v, cast_sizet(oldn) * sizeof(t), \
  72.                                   cast_sizet(n) * sizeof(t))))
  73.  
  74. #define luaM_shrinkvector(L,v,size,fs,t) \
  75.    ((v)=cast(t *, luaM_shrinkvector_(L, v, &(size), fs, sizeof(t))))
  76.  
  77. LUAI_FUNC l_noret luaM_toobig (lua_State *L);
  78.  
  79. /* not to be called directly */
  80. LUAI_FUNC void *luaM_realloc_ (lua_State *L, void *block, size_t oldsize,
  81.                                                           size_t size);
  82. LUAI_FUNC void *luaM_saferealloc_ (lua_State *L, void *block, size_t oldsize,
  83.                                                               size_t size);
  84. LUAI_FUNC void luaM_free_ (lua_State *L, void *block, size_t osize);
  85. LUAI_FUNC void *luaM_growaux_ (lua_State *L, void *block, int nelems,
  86.                                int *size, int size_elem, int limit,
  87.                                const char *what);
  88. LUAI_FUNC void *luaM_shrinkvector_ (lua_State *L, void *block, int *nelem,
  89.                                     int final_n, int size_elem);
  90. LUAI_FUNC void *luaM_malloc_ (lua_State *L, size_t size, int tag);
  91.  
  92. #endif
  93.  
  94.