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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 5205 | clevermous | 1 | /* |
| 2 | ** $Id: lbitlib.c,v 1.16 2011/06/20 16:35:23 roberto Exp $ |
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| 3 | ** Standard library for bitwise operations |
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| 4 | ** See Copyright Notice in lua.h |
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| 5 | */ |
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| 6 | |||
| 7 | #define lbitlib_c |
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| 8 | #define LUA_LIB |
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| 9 | |||
| 10 | #include "lua.h" |
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| 11 | |||
| 12 | #include "lauxlib.h" |
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| 13 | #include "lualib.h" |
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| 14 | |||
| 15 | |||
| 16 | /* number of bits to consider in a number */ |
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| 17 | #if !defined(LUA_NBITS) |
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| 18 | #define LUA_NBITS 32 |
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| 19 | #endif |
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| 20 | |||
| 21 | |||
| 22 | #define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1)) |
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| 23 | |||
| 24 | /* macro to trim extra bits */ |
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| 25 | #define trim(x) ((x) & ALLONES) |
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| 26 | |||
| 27 | |||
| 28 | /* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */ |
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| 29 | #define mask(n) (~((ALLONES << 1) << ((n) - 1))) |
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| 30 | |||
| 31 | |||
| 32 | typedef lua_Unsigned b_uint; |
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| 33 | |||
| 34 | |||
| 35 | |||
| 36 | static b_uint andaux (lua_State *L) { |
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| 37 | int i, n = lua_gettop(L); |
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| 38 | b_uint r = ~(b_uint)0; |
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| 39 | for (i = 1; i <= n; i++) |
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| 40 | r &= luaL_checkunsigned(L, i); |
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| 41 | return trim(r); |
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| 42 | } |
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| 43 | |||
| 44 | |||
| 45 | static int b_and (lua_State *L) { |
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| 46 | b_uint r = andaux(L); |
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| 47 | lua_pushunsigned(L, r); |
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| 48 | return 1; |
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| 49 | } |
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| 50 | |||
| 51 | |||
| 52 | static int b_test (lua_State *L) { |
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| 53 | b_uint r = andaux(L); |
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| 54 | lua_pushboolean(L, r != 0); |
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| 55 | return 1; |
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| 56 | } |
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| 57 | |||
| 58 | |||
| 59 | static int b_or (lua_State *L) { |
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| 60 | int i, n = lua_gettop(L); |
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| 61 | b_uint r = 0; |
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| 62 | for (i = 1; i <= n; i++) |
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| 63 | r |= luaL_checkunsigned(L, i); |
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| 64 | lua_pushunsigned(L, trim(r)); |
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| 65 | return 1; |
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| 66 | } |
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| 67 | |||
| 68 | |||
| 69 | static int b_xor (lua_State *L) { |
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| 70 | int i, n = lua_gettop(L); |
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| 71 | b_uint r = 0; |
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| 72 | for (i = 1; i <= n; i++) |
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| 73 | r ^= luaL_checkunsigned(L, i); |
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| 74 | lua_pushunsigned(L, trim(r)); |
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| 75 | return 1; |
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| 76 | } |
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| 77 | |||
| 78 | |||
| 79 | static int b_not (lua_State *L) { |
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| 80 | b_uint r = ~luaL_checkunsigned(L, 1); |
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| 81 | lua_pushunsigned(L, trim(r)); |
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| 82 | return 1; |
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| 83 | } |
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| 84 | |||
| 85 | |||
| 86 | static int b_shift (lua_State *L, b_uint r, int i) { |
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| 87 | if (i < 0) { /* shift right? */ |
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| 88 | i = -i; |
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| 89 | r = trim(r); |
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| 90 | if (i >= LUA_NBITS) r = 0; |
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| 91 | else r >>= i; |
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| 92 | } |
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| 93 | else { /* shift left */ |
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| 94 | if (i >= LUA_NBITS) r = 0; |
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| 95 | else r <<= i; |
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| 96 | r = trim(r); |
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| 97 | } |
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| 98 | lua_pushunsigned(L, r); |
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| 99 | return 1; |
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| 100 | } |
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| 101 | |||
| 102 | |||
| 103 | static int b_lshift (lua_State *L) { |
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| 104 | return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2)); |
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| 105 | } |
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| 106 | |||
| 107 | |||
| 108 | static int b_rshift (lua_State *L) { |
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| 109 | return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2)); |
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| 110 | } |
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| 111 | |||
| 112 | |||
| 113 | static int b_arshift (lua_State *L) { |
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| 114 | b_uint r = luaL_checkunsigned(L, 1); |
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| 115 | int i = luaL_checkint(L, 2); |
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| 116 | if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1)))) |
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| 117 | return b_shift(L, r, -i); |
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| 118 | else { /* arithmetic shift for 'negative' number */ |
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| 119 | if (i >= LUA_NBITS) r = ALLONES; |
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| 120 | else |
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| 121 | r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */ |
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| 122 | lua_pushunsigned(L, r); |
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| 123 | return 1; |
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| 124 | } |
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| 125 | } |
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| 126 | |||
| 127 | |||
| 128 | static int b_rot (lua_State *L, int i) { |
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| 129 | b_uint r = luaL_checkunsigned(L, 1); |
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| 130 | i &= (LUA_NBITS - 1); /* i = i % NBITS */ |
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| 131 | r = trim(r); |
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| 132 | r = (r << i) | (r >> (LUA_NBITS - i)); |
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| 133 | lua_pushunsigned(L, trim(r)); |
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| 134 | return 1; |
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| 135 | } |
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| 136 | |||
| 137 | |||
| 138 | static int b_lrot (lua_State *L) { |
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| 139 | return b_rot(L, luaL_checkint(L, 2)); |
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| 140 | } |
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| 141 | |||
| 142 | |||
| 143 | static int b_rrot (lua_State *L) { |
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| 144 | return b_rot(L, -luaL_checkint(L, 2)); |
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| 145 | } |
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| 146 | |||
| 147 | |||
| 148 | /* |
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| 149 | ** get field and width arguments for field-manipulation functions, |
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| 150 | ** checking whether they are valid |
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| 151 | */ |
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| 152 | static int fieldargs (lua_State *L, int farg, int *width) { |
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| 153 | int f = luaL_checkint(L, farg); |
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| 154 | int w = luaL_optint(L, farg + 1, 1); |
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| 155 | luaL_argcheck(L, 0 <= f, farg, "field cannot be negative"); |
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| 156 | luaL_argcheck(L, 0 < w, farg + 1, "width must be positive"); |
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| 157 | if (f + w > LUA_NBITS) |
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| 158 | luaL_error(L, "trying to access non-existent bits"); |
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| 159 | *width = w; |
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| 160 | return f; |
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| 161 | } |
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| 162 | |||
| 163 | |||
| 164 | static int b_extract (lua_State *L) { |
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| 165 | int w; |
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| 166 | b_uint r = luaL_checkunsigned(L, 1); |
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| 167 | int f = fieldargs(L, 2, &w); |
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| 168 | r = (r >> f) & mask(w); |
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| 169 | lua_pushunsigned(L, r); |
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| 170 | return 1; |
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| 171 | } |
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| 172 | |||
| 173 | |||
| 174 | static int b_replace (lua_State *L) { |
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| 175 | int w; |
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| 176 | b_uint r = luaL_checkunsigned(L, 1); |
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| 177 | b_uint v = luaL_checkunsigned(L, 2); |
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| 178 | int f = fieldargs(L, 3, &w); |
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| 179 | int m = mask(w); |
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| 180 | v &= m; /* erase bits outside given width */ |
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| 181 | r = (r & ~(m << f)) | (v << f); |
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| 182 | lua_pushunsigned(L, r); |
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| 183 | return 1; |
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| 184 | } |
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| 185 | |||
| 186 | |||
| 187 | static const luaL_Reg bitlib[] = { |
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| 188 | {"arshift", b_arshift}, |
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| 189 | {"band", b_and}, |
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| 190 | {"bnot", b_not}, |
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| 191 | {"bor", b_or}, |
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| 192 | {"bxor", b_xor}, |
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| 193 | {"btest", b_test}, |
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| 194 | {"extract", b_extract}, |
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| 195 | {"lrotate", b_lrot}, |
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| 196 | {"lshift", b_lshift}, |
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| 197 | {"replace", b_replace}, |
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| 198 | {"rrotate", b_rrot}, |
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| 199 | {"rshift", b_rshift}, |
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| 200 | {NULL, NULL} |
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| 201 | }; |
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| 202 | |||
| 203 | |||
| 204 | |||
| 205 | LUAMOD_API int luaopen_bit32 (lua_State *L) { |
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| 206 | luaL_newlib(L, bitlib); |
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| 207 | return 1; |
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| 208 | } |
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| 209 |