/* Bitwise operations library */ /* (c) Reuben Thomas 2000-2008 */ /* bitlib is copyright Reuben Thomas 2000-2008, and is released under the MIT license, like Lua (see http://www.lua.org/copyright.html; it's basically the same as the BSD license). There is no warranty. */ #include "config.h" #include "lua.h" #include "lauxlib.h" #include /* FIXME: Assume lua_Integer is ptrdiff_t */ #define LUA_INTEGER_MAX INTPTR_MAX #define LUA_INTEGER_MIN INTPTR_MIN /* FIXME: Assume size_t is an unsigned lua_Integer */ typedef size_t lua_UInteger; #define LUA_UINTEGER_MAX UINT_MAX /* Bit type size and limits */ #define BIT_BITS (CHAR_BIT * sizeof(lua_Integer)) /* This code may give warnings if BITLIB_FLOAT_* are too big to fit in long, but that doesn't matter since in that case they won't be used. */ #define BIT_MAX (LUA_INTEGER_MAX) #define BIT_MIN (LUA_INTEGER_MIN) #define BIT_UMAX (LUA_UINTEGER_MAX) /* Define TOBIT to get a bit value */ #ifdef BUILTIN_CAST #define #define TOBIT(L, n, res) \ ((void)(res), luaL_checkinteger((L), (n))) #else #define TOBIT(L, n, res) \ ((lua_Integer)(((res) = luaL_checknumber(L, (n)) % BIT_UMAX), \ (res) > BIT_MAX ? ((res) -= BIT_UMAX, (res) -= 1) : \ ((res) < BIT_MIN ? ((res) += BIT_UMAX, (res) += 1) : (res)))) #endif #define BIT_TRUNCATE(i) \ ((i) & BIT_UMAX) /* Operations The macros MONADIC and VARIADIC only deal with bitwise operations. LOGICAL_SHIFT truncates its left-hand operand before shifting so that any extra bits at the most-significant end are not shifted into the result. ARITHMETIC_SHIFT does not truncate its left-hand operand, so that the sign bits are not removed and right shift work properly. */ #define MONADIC(name, op) \ static int bit_ ## name(lua_State *L) { \ lua_Number f; \ lua_pushinteger(L, BIT_TRUNCATE(op TOBIT(L, 1, f))); \ return 1; \ } #define VARIADIC(name, op) \ static int bit_ ## name(lua_State *L) { \ lua_Number f; \ int n = lua_gettop(L), i; \ lua_Integer w = TOBIT(L, 1, f); \ for (i = 2; i <= n; i++) \ w op TOBIT(L, i, f); \ lua_pushinteger(L, BIT_TRUNCATE(w)); \ return 1; \ } #define LOGICAL_SHIFT(name, op) \ static int bit_ ## name(lua_State *L) { \ lua_Number f; \ lua_pushinteger(L, BIT_TRUNCATE(BIT_TRUNCATE((lua_UInteger)TOBIT(L, 1, f)) op \ (unsigned)luaL_checknumber(L, 2))); \ return 1; \ } #define ARITHMETIC_SHIFT(name, op) \ static int bit_ ## name(lua_State *L) { \ lua_Number f; \ lua_pushinteger(L, BIT_TRUNCATE((lua_Integer)TOBIT(L, 1, f) op \ (unsigned)luaL_checknumber(L, 2))); \ return 1; \ } MONADIC(bnot, ~) VARIADIC(band, &=) VARIADIC(bor, |=) VARIADIC(bxor, ^=) ARITHMETIC_SHIFT(lshift, <<) LOGICAL_SHIFT(rshift, >>) ARITHMETIC_SHIFT(arshift, >>) static const struct luaL_reg bitlib[] = { {"bnot", bit_bnot}, {"band", bit_band}, {"bor", bit_bor}, {"bxor", bit_bxor}, {"lshift", bit_lshift}, {"rshift", bit_rshift}, {"arshift", bit_arshift}, {NULL, NULL} }; LUALIB_API int luaopen_bit (lua_State *L) { luaL_register(L, "bit", bitlib); lua_pushnumber(L, BIT_BITS); lua_setfield(L, -2, "bits"); return 1; } 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250