commit 88564c3aec8122ce20bd257e01d4ab32c9663051
parent 3abe3da9fb9baf24e4e9e1cfb0212cce00d70fee
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 1 Jul 2009 13:16:44 -0300
Standard library for bitwise operations
Diffstat:
A | lbitlib.c | | | 123 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 123 insertions(+), 0 deletions(-)
diff --git a/lbitlib.c b/lbitlib.c
@@ -0,0 +1,123 @@
+/*
+** $Id: $
+** Standard library for bitwise operations
+** See Copyright Notice in lua.h
+*/
+
+#include "lua.h"
+
+#include "lauxlib.h"
+#include "lualib.h"
+
+
+/* number of bits considered when shifting/rotating (must be a power of 2) */
+#define NBITS 32
+
+
+typedef LUA_INT32 b_int;
+typedef unsigned LUA_INT32 b_uint;
+
+
+static b_uint getuintarg (lua_State *L, int arg) {
+ b_uint r;
+ lua_Number x = lua_tonumber(L, arg);
+ if (x == 0) luaL_checktype(L, arg, LUA_TNUMBER);
+ lua_number2uint(r, x);
+ return r;
+}
+
+
+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 r;
+}
+
+
+static int b_and (lua_State *L) {
+ b_uint r = andaux(L);
+ lua_pushnumber(L, lua_uint2number(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_pushnumber(L, lua_uint2number(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_pushnumber(L, lua_uint2number(r));
+ return 1;
+}
+
+
+static int b_not (lua_State *L) {
+ b_uint r = ~getuintarg(L, 1);
+ lua_pushnumber(L, lua_uint2number(r));
+ return 1;
+}
+
+
+static int b_shift (lua_State *L) {
+ b_uint r = getuintarg(L, 1);
+ lua_Integer i = luaL_checkinteger(L, 2);
+ if (i < 0) { /* shift right? */
+ i = -i;
+ if (i >= NBITS) r = 0;
+ else r >>= i;
+ }
+ else { /* shift left */
+ if (i >= NBITS) r = 0;
+ else r <<= i;
+ }
+ lua_pushnumber(L, lua_uint2number(r));
+ return 1;
+}
+
+
+static int b_rotate (lua_State *L) {
+ b_uint r = getuintarg(L, 1);
+ lua_Integer i = luaL_checkinteger(L, 2);
+ i &= (NBITS - 1); /* i = i % NBITS */
+ r = (r << i) | (r >> (NBITS - i));
+ lua_pushnumber(L, lua_uint2number(r));
+ return 1;
+}
+
+
+static const luaL_Reg bitlib[] = {
+ {"band", b_and},
+ {"btest", b_test},
+ {"bor", b_or},
+ {"bxor", b_xor},
+ {"bnot", b_not},
+ {"bshift", b_shift},
+ {"brotate", b_rotate},
+ {NULL, NULL}
+};
+
+
+
+LUALIB_API int luaopen_bit (lua_State *L) {
+ luaL_register(L, LUA_BITLIBNAME, bitlib);
+ return 1;
+}