Lua lmem.h (5.3.5)

** $Id: lmem.h,v 2017/04/19 17:20:42 roberto Exp $
** Interface to Memory Manager
** See Copyright Notice in lua.h

#ifndef lmem_h
#define lmem_h

#include <stddef.h>

#include "llimits.h"
#include "lua.h"

** This macro reallocs a vector 'b' from 'on' to 'n' elements, where
** each element has size 'e'. In case of arithmetic overflow of the
** product 'n'*'e', it raises an error (calling 'luaM_toobig'). Because
** 'e' is always constant, it avoids the runtime division MAX_SIZET/(e).
** (The macro is somewhat complex to avoid warnings:  The 'sizeof'
** comparison avoids a runtime comparison when overflow cannot occur.
** The compiler should be able to optimize the real test by itself, but
** when it does it, it may give a warning about "comparison is always
** false due to limited range of data type"; the +1 tricks the compiler,
** avoiding this warning but also this optimization.)
#define luaM_reallocv(L,b,on,n,e) \
  (((sizeof(n) >= sizeof(size_t) && cast(size_t, (n)) + 1 > MAX_SIZET/(e)) \
      ? luaM_toobig(L) : cast_void(0)) , \
   luaM_realloc_(L, (b), (on)*(e), (n)*(e)))

** Arrays of chars do not need any test
#define luaM_reallocvchar(L,b,on,n)  \
    cast(char *, luaM_realloc_(L, (b), (on)*sizeof(char), (n)*sizeof(char)))

#define luaM_freemem(L, b, s)   luaM_realloc_(L, (b), (s), 0)
#define luaM_free(L, b)         luaM_realloc_(L, (b), sizeof(*(b)), 0)
#define luaM_freearray(L, b, n)   luaM_realloc_(L, (b), (n)*sizeof(*(b)), 0)

#define luaM_malloc(L,s)        luaM_realloc_(L, NULL, 0, (s))
#define luaM_new(L,t)           cast(t *, luaM_malloc(L, sizeof(t)))
#define luaM_newvector(L,n,t) \
                cast(t *, luaM_reallocv(L, NULL, 0, n, sizeof(t)))

#define luaM_newobject(L,tag,s) luaM_realloc_(L, NULL, tag, (s))

#define luaM_growvector(L,v,nelems,size,t,limit,e) \
          if ((nelems)+1 > (size)) \
            ((v)=cast(t *, luaM_growaux_(L,v,&(size),sizeof(t),limit,e)))

#define luaM_reallocvector(L, v,oldn,n,t) \
   ((v)=cast(t *, luaM_reallocv(L, v, oldn, n, sizeof(t))))

LUAI_FUNC l_noret luaM_toobig (lua_State *L);

/* not to be called directly */
LUAI_FUNC void *luaM_realloc_ (lua_State *L, void *block, size_t oldsize,
                                                          size_t size);
LUAI_FUNC void *luaM_growaux_ (lua_State *L, void *block, int *size,
                               size_t size_elem, int limit,
                               const char *what);