mirror of https://github.com/lua/lua
124 lines
2.2 KiB
C
124 lines
2.2 KiB
C
/*
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** $Id: $
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** Standard library for bitwise operations
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** See Copyright Notice in lua.h
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*/
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#include "lua.h"
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#include "lauxlib.h"
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#include "lualib.h"
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/* number of bits considered when shifting/rotating (must be a power of 2) */
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#define NBITS 32
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typedef LUA_INT32 b_int;
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typedef unsigned LUA_INT32 b_uint;
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static b_uint getuintarg (lua_State *L, int arg) {
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b_uint r;
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lua_Number x = lua_tonumber(L, arg);
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if (x == 0) luaL_checktype(L, arg, LUA_TNUMBER);
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lua_number2uint(r, x);
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return r;
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}
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static b_uint andaux (lua_State *L) {
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int i, n = lua_gettop(L);
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b_uint r = ~(b_uint)0;
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for (i = 1; i <= n; i++)
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r &= getuintarg(L, i);
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return r;
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}
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static int b_and (lua_State *L) {
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b_uint r = andaux(L);
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lua_pushnumber(L, lua_uint2number(r));
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return 1;
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}
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static int b_test (lua_State *L) {
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b_uint r = andaux(L);
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lua_pushboolean(L, r != 0);
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return 1;
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}
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static int b_or (lua_State *L) {
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int i, n = lua_gettop(L);
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b_uint r = 0;
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for (i = 1; i <= n; i++)
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r |= getuintarg(L, i);
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lua_pushnumber(L, lua_uint2number(r));
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return 1;
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}
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static int b_xor (lua_State *L) {
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int i, n = lua_gettop(L);
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b_uint r = 0;
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for (i = 1; i <= n; i++)
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r ^= getuintarg(L, i);
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lua_pushnumber(L, lua_uint2number(r));
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return 1;
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}
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static int b_not (lua_State *L) {
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b_uint r = ~getuintarg(L, 1);
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lua_pushnumber(L, lua_uint2number(r));
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return 1;
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}
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static int b_shift (lua_State *L) {
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b_uint r = getuintarg(L, 1);
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lua_Integer i = luaL_checkinteger(L, 2);
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if (i < 0) { /* shift right? */
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i = -i;
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if (i >= NBITS) r = 0;
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else r >>= i;
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}
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else { /* shift left */
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if (i >= NBITS) r = 0;
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else r <<= i;
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}
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lua_pushnumber(L, lua_uint2number(r));
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return 1;
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}
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static int b_rotate (lua_State *L) {
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b_uint r = getuintarg(L, 1);
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lua_Integer i = luaL_checkinteger(L, 2);
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i &= (NBITS - 1); /* i = i % NBITS */
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r = (r << i) | (r >> (NBITS - i));
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lua_pushnumber(L, lua_uint2number(r));
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return 1;
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}
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static const luaL_Reg bitlib[] = {
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{"band", b_and},
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{"btest", b_test},
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{"bor", b_or},
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{"bxor", b_xor},
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{"bnot", b_not},
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{"bshift", b_shift},
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{"brotate", b_rotate},
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{NULL, NULL}
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};
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LUALIB_API int luaopen_bit (lua_State *L) {
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luaL_register(L, LUA_BITLIBNAME, bitlib);
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return 1;
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}
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