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bitlib renamed to 'bit32' + new function for arithmetic shift

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This commit is contained in:
Roberto Ierusalimschy
2010-10-25 12:32:36 -02:00
parent d72ec210c7
commit 9e8e60dd5f
3 changed files with 26 additions and 11 deletions
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27
lbitlib.c
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@@ -1,5 +1,5 @@
/*
** $Id: lbitlib.c,v 1.5 2010/07/02 11:38:13 roberto Exp roberto $
** $Id: lbitlib.c,v 1.6 2010/07/02 12:01:53 roberto Exp roberto $
** Standard library for bitwise operations
** See Copyright Notice in lua.h
*/
@@ -81,8 +81,7 @@ static int b_not (lua_State *L) {
}
static int b_shift (lua_State *L, int i) {
b_uint r = getuintarg(L, 1);
static int b_shift (lua_State *L, b_uint r, int i) {
if (i < 0) { /* shift right? */
i = -i;
if (i >= NBITS) r = 0;
@@ -98,12 +97,27 @@ static int b_shift (lua_State *L, int i) {
static int b_lshift (lua_State *L) {
return b_shift(L, luaL_checkint(L, 2));
return b_shift(L, getuintarg(L, 1), luaL_checkint(L, 2));
}
static int b_rshift (lua_State *L) {
return b_shift(L, -luaL_checkint(L, 2));
return b_shift(L, getuintarg(L, 1), -luaL_checkint(L, 2));
}
static int b_arshift (lua_State *L) {
b_uint r = getuintarg(L, 1);
int i = luaL_checkint(L, 2);
if (i < 0 || !(r & 0x80000000))
return b_shift(L, r, -i);
else { /* arithmetic shift for 'negative' number */
if (i >= NBITS) r = 0xffffffff;
else
r = (r >> i) | ~(~(b_uint)0 >> i); /* add signal bit */
lua_pushnumber(L, lua_uint2number(r));
return 1;
}
}
@@ -133,6 +147,7 @@ static const luaL_Reg bitlib[] = {
{"bxor", b_xor},
{"bnot", b_not},
{"lshift", b_lshift},
{"arshift", b_arshift},
{"rshift", b_rshift},
{"rol", b_rol},
{"ror", b_ror},
@@ -141,7 +156,7 @@ static const luaL_Reg bitlib[] = {
LUAMOD_API int luaopen_bit (lua_State *L) {
LUAMOD_API int luaopen_bit32 (lua_State *L) {
luaL_newlib(L, bitlib);
return 1;
}