epan/wslua/lua_bitop.c

   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 #define LUA_BITOP_VERSION       "1.0.2"
  30
  31 #define LUA_LIB
  32 #include <lua.h>
  33 #include <lauxlib.h>
  34
  35 #ifdef _MSC_VER
  36 /* MSVC is stuck in the last century and doesn't have C99's stdint.h. */
  37 typedef __int32 int32_t;
  38 typedef unsigned __int32 uint32_t;
  39 typedef unsigned __int64 uint64_t;
  40 #else
  41 #include <stdint.h>
  42 #endif
  43
  44 typedef int32_t SBits;
  45 typedef uint32_t UBits;
  46
  47 typedef union {
  48   lua_Number n;
  49 #ifdef LUA_NUMBER_DOUBLE
  50   uint64_t b;
  51 #else
  52   UBits b;
  53 #endif
  54 } BitNum;
  55
  56 /* Convert argument to bit type. */
  57 static UBits barg(lua_State *L, int idx)
  58 {
  59   BitNum bn;
  60   UBits b;
  61 #if LUA_VERSION_NUM < 502
  62   bn.n = lua_tonumber(L, idx);
  63 #else
  64   bn.n = luaL_checknumber(L, idx);
  65 #endif
  66 #if defined(LUA_NUMBER_DOUBLE)
  67   bn.n += 6755399441055744.0;  /* 2^52+2^51 */
  68 #ifdef SWAPPED_DOUBLE
  69   b = (UBits)(bn.b >> 32);
  70 #else
  71   b = (UBits)bn.b;
  72 #endif
  73 #elif defined(LUA_NUMBER_INT) || defined(LUA_NUMBER_LONG) || \
  74       defined(LUA_NUMBER_LONGLONG) || defined(LUA_NUMBER_LONG_LONG) || \
  75       defined(LUA_NUMBER_LLONG)
  76   if (sizeof(UBits) == sizeof(lua_Number))
  77     b = bn.b;
  78   else
  79     b = (UBits)(SBits)bn.n;
  80 #elif defined(LUA_NUMBER_FLOAT)
  81 #error "A 'float' lua_Number type is incompatible with this library"
  82 #else
  83 #error "Unknown number type, check LUA_NUMBER_* in luaconf.h"
  84 #endif
  85 #if LUA_VERSION_NUM < 502
  86   if (b == 0 && !lua_isnumber(L, idx)) {
  87     luaL_typerror(L, idx, "number");
  88   }
  89 #endif
  90   return b;
  91 }
  92
  93 /* Return bit type. */
  94 #define BRET(b)  lua_pushnumber(L, (lua_Number)(SBits)(b)); return 1;
  95
  96 static int bit_tobit(lua_State *L) { BRET(barg(L, 1)) }
  97 static int bit_bnot(lua_State *L) { BRET(~barg(L, 1)) }
  98
  99 #define BIT_OP(func, opr) \
 100   static int func(lua_State *L) { int i; UBits b = barg(L, 1); \
 101     for (i = lua_gettop(L); i > 1; i--) b opr barg(L, i); BRET(b) }
 102 BIT_OP(bit_band, &=)
 103 BIT_OP(bit_bor, |=)
 104 BIT_OP(bit_bxor, ^=)
 105
 106 #define bshl(b, n)  (b << n)
 107 #define bshr(b, n)  (b >> n)
 108 #define bsar(b, n)  ((SBits)b >> n)
 109 #define brol(b, n)  ((b << n) | (b >> (32-n)))
 110 #define bror(b, n)  ((b << (32-n)) | (b >> n))
 111 #define BIT_SH(func, fn) \
 112   static int func(lua_State *L) { \
 113     UBits b = barg(L, 1); UBits n = barg(L, 2) & 31; BRET(fn(b, n)) }
 114 BIT_SH(bit_lshift, bshl)
 115 BIT_SH(bit_rshift, bshr)
 116 BIT_SH(bit_arshift, bsar)
 117 BIT_SH(bit_rol, brol)
 118 BIT_SH(bit_ror, bror)
 119
 120 static int bit_bswap(lua_State *L)
 121 {
 122   UBits b = barg(L, 1);
 123   b = (b >> 24) | ((b >> 8) & 0xff00) | ((b & 0xff00) << 8) | (b << 24);
 124   BRET(b)
 125 }
 126
 127 static int bit_tohex(lua_State *L)
 128 {
 129   UBits b = barg(L, 1);
 130   SBits n = lua_isnone(L, 2) ? 8 : (SBits)barg(L, 2);
 131   const char *hexdigits = "0123456789abcdef";
 132   char buf[8];
 133   int i;
 134   if (n < 0) { n = -n; hexdigits = "0123456789ABCDEF"; }
 135   if (n > 8) n = 8;
 136   for (i = (int)n; --i >= 0; ) { buf[i] = hexdigits[b & 15]; b >>= 4; }
 137   lua_pushlstring(L, buf, (size_t)n);
 138   return 1;
 139 }
 140
 141 static const struct luaL_Reg bit_funcs[] = {
 142   { "tobit",    bit_tobit },
 143   { "bnot",     bit_bnot },
 144   { "band",     bit_band },
 145   { "bor",      bit_bor },
 146   { "bxor",     bit_bxor },
 147   { "lshift",   bit_lshift },
 148   { "rshift",   bit_rshift },
 149   { "arshift",  bit_arshift },
 150   { "rol",      bit_rol },
 151   { "ror",      bit_ror },
 152   { "bswap",    bit_bswap },
 153   { "tohex",    bit_tohex },
 154   { NULL, NULL }
 155 };
 156
 157 /* Signed right-shifts are implementation-defined per C89/C99.
 158 ** But the de facto standard are arithmetic right-shifts on two's
 159 ** complement CPUs. This behaviour is required here, so test for it.
 160 */
 161 #define BAD_SAR         (bsar(-8, 2) != (SBits)-2)
 162
 163 LUALIB_API int luaopen_bit(lua_State *L)
 164 {
 165   UBits b;
 166   lua_pushnumber(L, (lua_Number)1437217655L);
 167   b = barg(L, -1);
 168   if (b != (UBits)1437217655L || BAD_SAR) {  /* Perform a simple self-test. */
 169     const char *msg = "compiled with incompatible luaconf.h";
 170 #ifdef LUA_NUMBER_DOUBLE
 171 #ifdef _WIN32
 172     if (b == (UBits)1610612736L)
 173       msg = "use D3DCREATE_FPU_PRESERVE with DirectX";
 174 #endif
 175     if (b == (UBits)1127743488L)
 176       msg = "not compiled with SWAPPED_DOUBLE";
 177 #endif
 178     if (BAD_SAR)
 179       msg = "arithmetic right-shift broken";
 180     luaL_error(L, "bit library self-test failed (%s)", msg);
 181   }
 182 #if LUA_VERSION_NUM < 502
 183   luaL_register(L, "bit", bit_funcs);
 184 #else
 185   luaL_newlib(L, bit_funcs);
 186 #endif
 187   return 1;
 188 }
 189