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lmem.h (3435B)


      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' 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_int((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)  \
     61 	cast(t*, luaM_malloc_(L, cast_sizet(n)*sizeof(t), 0))
     62 #define luaM_newvectorchecked(L,n,t) \
     63   (luaM_checksize(L,n,sizeof(t)), luaM_newvector(L,n,t))
     64 
     65 #define luaM_newobject(L,tag,s)	luaM_malloc_(L, (s), tag)
     66 
     67 #define luaM_newblock(L, size)	luaM_newvector(L, size, char)
     68 
     69 #define luaM_growvector(L,v,nelems,size,t,limit,e) \
     70 	((v)=cast(t *, luaM_growaux_(L,v,nelems,&(size),sizeof(t), \
     71                          luaM_limitN(limit,t),e)))
     72 
     73 #define luaM_reallocvector(L, v,oldn,n,t) \
     74    (cast(t *, luaM_realloc_(L, v, cast_sizet(oldn) * sizeof(t), \
     75                                   cast_sizet(n) * sizeof(t))))
     76 
     77 #define luaM_shrinkvector(L,v,size,fs,t) \
     78    ((v)=cast(t *, luaM_shrinkvector_(L, v, &(size), fs, sizeof(t))))
     79 
     80 LUAI_FUNC l_noret luaM_toobig (lua_State *L);
     81 
     82 /* not to be called directly */
     83 LUAI_FUNC void *luaM_realloc_ (lua_State *L, void *block, size_t oldsize,
     84                                                           size_t size);
     85 LUAI_FUNC void *luaM_saferealloc_ (lua_State *L, void *block, size_t oldsize,
     86                                                               size_t size);
     87 LUAI_FUNC void luaM_free_ (lua_State *L, void *block, size_t osize);
     88 LUAI_FUNC void *luaM_growaux_ (lua_State *L, void *block, int nelems,
     89                                int *size, unsigned size_elem, int limit,
     90                                const char *what);
     91 LUAI_FUNC void *luaM_shrinkvector_ (lua_State *L, void *block, int *nelem,
     92                                     int final_n, unsigned size_elem);
     93 LUAI_FUNC void *luaM_malloc_ (lua_State *L, size_t size, int tag);
     94 
     95 #endif
     96