diff options
Diffstat (limited to 'lua/lmem.h')
| -rw-r--r-- | lua/lmem.h | 30 |
1 files changed, 21 insertions, 9 deletions
@@ -1,5 +1,5 @@ /* -** $Id: lmem.h,v 1.40.1.1 2013/04/12 18:48:47 roberto Exp $ +** $Id: lmem.h,v 1.43 2014/12/19 17:26:14 roberto Exp $ ** Interface to Memory Manager ** See Copyright Notice in lua.h */ @@ -15,20 +15,32 @@ /* -** This macro avoids the runtime division MAX_SIZET/(e), as 'e' is -** always constant. -** The macro is somewhat complex to avoid warnings: -** +1 avoids warnings of "comparison has constant result"; -** cast to 'void' avoids warnings of "value unused". +** 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) \ - (cast(void, \ - (cast(size_t, (n)+1) > MAX_SIZET/(e)) ? (luaM_toobig(L), 0) : 0), \ + (((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_reallocv(L, (b), n, 0, 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))) |