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/*
** $Id: lbitlib.c,v 1.12 2010/11/22 16:39:20 roberto Exp roberto $
** Standard library for bitwise operations
** See Copyright Notice in lua.h
*/
#define lbitlib_c
#define LUA_LIB
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
/* number of bits to consider in a number */
#define NBITS 32
#define ALLONES (~(((~(lua_Unsigned)0) << (NBITS - 1)) << 1))
/* mask to trim extra bits */
#define trim(x) ((x) & ALLONES)
typedef lua_Unsigned b_uint;
#define getuintarg(L,arg) luaL_checkunsigned(L,arg)
static b_uint andaux (lua_State *L) {
int i, n = lua_gettop(L);
b_uint r = ~(b_uint)0;
for (i = 1; i <= n; i++)
r &= getuintarg(L, i);
return trim(r);
}
static int b_and (lua_State *L) {
b_uint r = andaux(L);
lua_pushunsigned(L, r);
return 1;
}
static int b_test (lua_State *L) {
b_uint r = andaux(L);
lua_pushboolean(L, r != 0);
return 1;
}
static int b_or (lua_State *L) {
int i, n = lua_gettop(L);
b_uint r = 0;
for (i = 1; i <= n; i++)
r |= getuintarg(L, i);
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_xor (lua_State *L) {
int i, n = lua_gettop(L);
b_uint r = 0;
for (i = 1; i <= n; i++)
r ^= getuintarg(L, i);
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_not (lua_State *L) {
b_uint r = ~getuintarg(L, 1);
lua_pushunsigned(L, trim(r));
return 1;
}
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;
else r >>= i;
}
else { /* shift left */
if (i >= NBITS) r = 0;
else r <<= i;
r = trim(r);
}
lua_pushunsigned(L, r);
return 1;
}
static int b_lshift (lua_State *L) {
return b_shift(L, getuintarg(L, 1), luaL_checkint(L, 2));
}
static int b_rshift (lua_State *L) {
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 & ((b_uint)1 << (NBITS - 1))))
return b_shift(L, r, -i);
else { /* arithmetic shift for 'negative' number */
if (i >= NBITS) r = ALLONES;
else
r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */
lua_pushunsigned(L, r);
return 1;
}
}
static int b_rot (lua_State *L, int i) {
b_uint r = getuintarg(L, 1);
i &= (NBITS - 1); /* i = i % NBITS */
r = trim(r);
r = (r << i) | (r >> (NBITS - i));
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_lrot (lua_State *L) {
return b_rot(L, luaL_checkint(L, 2));
}
static int b_rrot (lua_State *L) {
return b_rot(L, -luaL_checkint(L, 2));
}
static const luaL_Reg bitlib[] = {
{"arshift", b_arshift},
{"band", b_and},
{"bnot", b_not},
{"bor", b_or},
{"bxor", b_xor},
{"lrotate", b_lrot},
{"lshift", b_lshift},
{"rrotate", b_rrot},
{"rshift", b_rshift},
{"btest", b_test},
{NULL, NULL}
};
LUAMOD_API int luaopen_bit32 (lua_State *L) {
luaL_newlib(L, bitlib);
return 1;
}
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