/* ** \$Id: lbitlib.c,v 1.18.1.2 2013/07/09 18:01:41 roberto Exp \$ ** 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 */ #if !defined(LUA_NBITS) #define LUA_NBITS 32 #endif #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 <= LUA_NBITS) */ #define mask(n) (~((ALLONES << 1) << ((n) - 1))) typedef lua_Unsigned b_uint; 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 &= luaL_checkunsigned(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 |= luaL_checkunsigned(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 ^= luaL_checkunsigned(L, i); lua_pushunsigned(L, trim(r)); return 1; } static int b_not (lua_State *L) { b_uint r = ~luaL_checkunsigned(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 >= LUA_NBITS) r = 0; else r >>= i; } else { /* shift left */ if (i >= LUA_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, luaL_checkunsigned(L, 1), luaL_checkint(L, 2)); } static int b_rshift (lua_State *L) { return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2)); } 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 << (LUA_NBITS - 1)))) return b_shift(L, r, -i); else { /* arithmetic shift for 'negative' number */ if (i >= LUA_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 = luaL_checkunsigned(L, 1); i &= (LUA_NBITS - 1); /* i = i % NBITS */ r = trim(r); if (i != 0) /* avoid undefined shift of LUA_NBITS when i == 0 */ r = (r << i) | (r >> (LUA_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)); } /* ** get field and width arguments for field-manipulation functions, ** checking whether they are valid. ** ('luaL_error' called without 'return' to avoid later warnings about ** 'width' being used uninitialized.) */ static int fieldargs (lua_State *L, int farg, int *width) { int f = luaL_checkint(L, farg); int w = luaL_optint(L, farg + 1, 1); luaL_argcheck(L, 0 <= f, farg, "field cannot be negative"); luaL_argcheck(L, 0 < w, farg + 1, "width must be positive"); if (f + w > LUA_NBITS) luaL_error(L, "trying to access non-existent bits"); *width = w; return f; } static int b_extract (lua_State *L) { int w; b_uint r = luaL_checkunsigned(L, 1); int f = fieldargs(L, 2, &w); r = (r >> f) & mask(w); lua_pushunsigned(L, r); return 1; } static int b_replace (lua_State *L) { int w; b_uint r = luaL_checkunsigned(L, 1); b_uint v = luaL_checkunsigned(L, 2); int f = fieldargs(L, 3, &w); int m = mask(w); v &= m; /* erase bits outside given width */ r = (r & ~(m << f)) | (v << f); lua_pushunsigned(L, r); return 1; } static const luaL_Reg bitlib[] = { {"arshift", b_arshift}, {"band", b_and}, {"bnot", b_not}, {"bor", b_or}, {"bxor", b_xor}, {"btest", b_test}, {"extract", b_extract}, {"lrotate", b_lrot}, {"lshift", b_lshift}, {"replace", b_replace}, {"rrotate", b_rrot}, {"rshift", b_rshift}, {NULL, NULL} }; LUAMOD_API int luaopen_bit32 (lua_State *L) { luaL_newlib(L, bitlib); return 1; }