lib/bitop/bit.cpp

   1 /*
   2 ** Lua BitOp -- a bit operations library for Lua 5.1/5.2.
   3 ** http://bitop.luajit.org/
   4 **
   5 ** Copyright (C) 2008-2012 Mike Pall. All rights reserved.
   6 **
   7 ** Permission is hereby granted, free of charge, to any person obtaining
   8 ** a copy of this software and associated documentation files (the
   9 ** "Software"), to deal in the Software without restriction, including
  10 ** without limitation the rights to use, copy, modify, merge, publish,
  11 ** distribute, sublicense, and/or sell copies of the Software, and to
  12 ** permit persons to whom the Software is furnished to do so, subject to
  13 ** the following conditions:
  14 **
  15 ** The above copyright notice and this permission notice shall be
  16 ** included in all copies or substantial portions of the Software.
  17 **
  18 ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19 ** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20 ** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  21 ** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  22 ** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23 ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24 ** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25 **
  26 ** [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
  27 */
  28
  29 extern "C" {
  30 #include "bit.h"
  31 }
  32
  33 #define LUA_BITOP_VERSION       "1.0.2"
  34
  35 #define LUA_LIB
  36 extern "C" {
  37 #include "lauxlib.h"
  38 }
  39
  40 #if defined(_MSC_VER) && (_MSC_VER < 1700)
  41 /* Old MSVC is stuck in the last century and doesn't have C99's stdint.h. */
  42 typedef __int32 int32_t;
  43 typedef unsigned __int32 uint32_t;
  44 typedef unsigned __int64 uint64_t;
  45 #else
  46 #include <stdint.h>
  47 #endif
  48
  49 typedef int32_t SBits;
  50 typedef uint32_t UBits;
  51
  52 typedef union {
  53   lua_Number n;
  54 #ifdef LUA_NUMBER_DOUBLE
  55   uint64_t b;
  56 #else
  57   UBits b;
  58 #endif
  59 } BitNum;
  60
  61 /* Convert argument to bit type. */
  62 static UBits barg(lua_State *L, int idx)
  63 {
  64   BitNum bn;
  65   UBits b;
  66 #if LUA_VERSION_NUM < 502
  67   bn.n = lua_tonumber(L, idx);
  68 #else
  69   bn.n = luaL_checknumber(L, idx);
  70 #endif
  71 #if defined(LUA_NUMBER_DOUBLE)
  72   bn.n += 6755399441055744.0;  /* 2^52+2^51 */
  73 #ifdef SWAPPED_DOUBLE
  74   b = (UBits)(bn.b >> 32);
  75 #else
  76   b = (UBits)bn.b;
  77 #endif
  78 #elif defined(LUA_NUMBER_INT) || defined(LUA_NUMBER_LONG) || \
  79       defined(LUA_NUMBER_LONGLONG) || defined(LUA_NUMBER_LONG_LONG) || \
  80       defined(LUA_NUMBER_LLONG)
  81   if (sizeof(UBits) == sizeof(lua_Number))
  82     b = bn.b;
  83   else
  84     b = (UBits)(SBits)bn.n;
  85 #elif defined(LUA_NUMBER_FLOAT)
  86 #error "A 'float' lua_Number type is incompatible with this library"
  87 #else
  88 #error "Unknown number type, check LUA_NUMBER_* in luaconf.h"
  89 #endif
  90 #if LUA_VERSION_NUM < 502
  91   if (b == 0 && !lua_isnumber(L, idx)) {
  92     luaL_typerror(L, idx, "number");
  93   }
  94 #endif
  95   return b;
  96 }
  97
  98 /* Return bit type. */
  99 #define BRET(b)  lua_pushnumber(L, (lua_Number)(SBits)(b)); return 1;
 100
 101 static int bit_tobit(lua_State *L) { BRET(barg(L, 1)) }
 102 static int bit_bnot(lua_State *L) { BRET(~barg(L, 1)) }
 103
 104 #define BIT_OP(func, opr) \
 105   static int func(lua_State *L) { int i; UBits b = barg(L, 1); \
 106     for (i = lua_gettop(L); i > 1; i--) b opr barg(L, i); BRET(b) }
 107 BIT_OP(bit_band, &=)
 108 BIT_OP(bit_bor, |=)
 109 BIT_OP(bit_bxor, ^=)
 110
 111 #define bshl(b, n)  (b << n)
 112 #define bshr(b, n)  (b >> n)
 113 #define bsar(b, n)  ((SBits)b >> n)
 114 #define brol(b, n)  ((b << n) | (b >> (32-n)))
 115 #define bror(b, n)  ((b << (32-n)) | (b >> n))
 116 #define BIT_SH(func, fn) \
 117   static int func(lua_State *L) { \
 118     UBits b = barg(L, 1); UBits n = barg(L, 2) & 31; BRET(fn(b, n)) }
 119 BIT_SH(bit_lshift, bshl)
 120 BIT_SH(bit_rshift, bshr)
 121 BIT_SH(bit_arshift, bsar)
 122 BIT_SH(bit_rol, brol)
 123 BIT_SH(bit_ror, bror)
 124
 125 static int bit_bswap(lua_State *L)
 126 {
 127   UBits b = barg(L, 1);
 128   b = (b >> 24) | ((b >> 8) & 0xff00) | ((b & 0xff00) << 8) | (b << 24);
 129   BRET(b)
 130 }
 131
 132 static int bit_tohex(lua_State *L)
 133 {
 134   UBits b = barg(L, 1);
 135   SBits n = lua_isnone(L, 2) ? 8 : (SBits)barg(L, 2);
 136   const char *hexdigits = "0123456789abcdef";
 137   char buf[8];
 138   int i;
 139   if (n < 0) { n = -n; hexdigits = "0123456789ABCDEF"; }
 140   if (n > 8) n = 8;
 141   for (i = (int)n; --i >= 0; ) { buf[i] = hexdigits[b & 15]; b >>= 4; }
 142   lua_pushlstring(L, buf, (size_t)n);
 143   return 1;
 144 }
 145
 146 static const struct luaL_Reg bit_funcs[] = {
 147   { "tobit",    bit_tobit },
 148   { "bnot",     bit_bnot },
 149   { "band",     bit_band },
 150   { "bor",      bit_bor },
 151   { "bxor",     bit_bxor },
 152   { "lshift",   bit_lshift },
 153   { "rshift",   bit_rshift },
 154   { "arshift",  bit_arshift },
 155   { "rol",      bit_rol },
 156   { "ror",      bit_ror },
 157   { "bswap",    bit_bswap },
 158   { "tohex",    bit_tohex },
 159   { NULL, NULL }
 160 };
 161
 162 /* Signed right-shifts are implementation-defined per C89/C99.
 163 ** But the de facto standard are arithmetic right-shifts on two's
 164 ** complement CPUs. This behaviour is required here, so test for it.
 165 */
 166 #define BAD_SAR         (bsar(-8, 2) != (SBits)-2)
 167
 168 LUALIB_API int luaopen_bit(lua_State *L)
 169 {
 170   UBits b;
 171   lua_pushnumber(L, (lua_Number)1437217655L);
 172   b = barg(L, -1);
 173   if (b != (UBits)1437217655L || BAD_SAR) {  /* Perform a simple self-test. */
 174     const char *msg = "compiled with incompatible luaconf.h";
 175 #ifdef LUA_NUMBER_DOUBLE
 176 #ifdef _WIN32
 177     if (b == (UBits)1610612736L)
 178       msg = "use D3DCREATE_FPU_PRESERVE with DirectX";
 179 #endif
 180     if (b == (UBits)1127743488L)
 181       msg = "not compiled with SWAPPED_DOUBLE";
 182 #endif
 183     if (BAD_SAR)
 184       msg = "arithmetic right-shift broken";
 185     luaL_error(L, "bit library self-test failed (%s)", msg);
 186   }
 187 #if LUA_VERSION_NUM < 502
 188   luaL_register(L, "bit", bit_funcs);
 189 #else
 190   luaL_newlib(L, bit_funcs);
 191 #endif
 192   return 1;
 193 }