zombiezen.com/go/lua@v0.0.0-20231013005828-290725fb9140/internal/lua54/lmem.h (about)

     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