commit 1a92c2b354bd08031a744cb39125a8c5d04349c3
parent fe0d54d37edd3d28d42a01db013e04cc12e97f2f
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Fri, 17 Dec 2010 11:26:14 -0200
allows number of bits used by the library to be changed from outside
Diffstat:
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/lbitlib.c b/lbitlib.c
@@ -1,5 +1,5 @@
/*
-** $Id: lbitlib.c,v 1.13 2010/11/22 18:06:33 roberto Exp roberto $
+** $Id: lbitlib.c,v 1.14 2010/11/29 15:19:28 roberto Exp roberto $
** Standard library for bitwise operations
** See Copyright Notice in lua.h
*/
@@ -14,15 +14,18 @@
/* number of bits to consider in a number */
-#define NBITS 32
+#if !defined(LUA_NBITS)
+#define LUA_NBITS 32
+#endif
-#define ALLONES (~(((~(lua_Unsigned)0) << (NBITS - 1)) << 1))
+
+#define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1))
/* macro to trim extra bits */
#define trim(x) ((x) & ALLONES)
-/* builds a number with 'n' ones (1 <= n <= NBITS) */
+/* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */
#define mask(n) (~((ALLONES << 1) << ((n) - 1)))
@@ -84,11 +87,11 @@ static int b_shift (lua_State *L, b_uint r, int i) {
if (i < 0) { /* shift right? */
i = -i;
r = trim(r);
- if (i >= NBITS) r = 0;
+ if (i >= LUA_NBITS) r = 0;
else r >>= i;
}
else { /* shift left */
- if (i >= NBITS) r = 0;
+ if (i >= LUA_NBITS) r = 0;
else r <<= i;
r = trim(r);
}
@@ -110,10 +113,10 @@ static int b_rshift (lua_State *L) {
static int b_arshift (lua_State *L) {
b_uint r = luaL_checkunsigned(L, 1);
int i = luaL_checkint(L, 2);
- if (i < 0 || !(r & ((b_uint)1 << (NBITS - 1))))
+ if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1))))
return b_shift(L, r, -i);
else { /* arithmetic shift for 'negative' number */
- if (i >= NBITS) r = ALLONES;
+ if (i >= LUA_NBITS) r = ALLONES;
else
r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */
lua_pushunsigned(L, r);
@@ -124,9 +127,9 @@ static int b_arshift (lua_State *L) {
static int b_rot (lua_State *L, int i) {
b_uint r = luaL_checkunsigned(L, 1);
- i &= (NBITS - 1); /* i = i % NBITS */
+ i &= (LUA_NBITS - 1); /* i = i % NBITS */
r = trim(r);
- r = (r << i) | (r >> (NBITS - i));
+ r = (r << i) | (r >> (LUA_NBITS - i));
lua_pushunsigned(L, trim(r));
return 1;
}
@@ -151,7 +154,7 @@ static int fieldargs (lua_State *L, int farg, int *width) {
int w = luaL_optint(L, farg + 1, 1);
luaL_argcheck(L, 0 <= f, farg, "field cannot be netative");
luaL_argcheck(L, 0 < w, farg + 1, "width must be positive");
- if (f + w > NBITS)
+ if (f + w > LUA_NBITS)
luaL_error(L, "trying to access non-existent bits");
*width = w;
return f;