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 ** SPDX-License-Identifier: MIT
   8 **
   9 */
  10
  11 #define LUA_BITOP_VERSION       "1.0.2"
  12
  13 #define LUA_LIB
  14 #include <lua.h>
  15 #include <lauxlib.h>
  16
  17 #include "lua_bitop.h"
  18 #include "ws_diag_control.h"
  19
  20 #include <stdint.h>
  21
  22 typedef int32_t SBits;
  23 typedef uint32_t UBits;
  24
  25 typedef union {
  26   lua_Number n;
  27 #if defined(LUA_NUMBER_DOUBLE) || defined(LUA_FLOAT_DOUBLE)
  28   uint64_t b;
  29 #else
  30   UBits b;
  31 #endif
  32 } BitNum;
  33
  34 /* Convert argument to bit type. */
  35 static UBits barg(lua_State *L, int idx)
  36 {
  37   BitNum bn;
  38   UBits b;
  39   bn.n = luaL_checknumber(L, idx);
  40 #if defined(LUA_NUMBER_DOUBLE) || defined(LUA_FLOAT_DOUBLE)
  41   bn.n += 6755399441055744.0;  /* 2^52+2^51 */
  42 #ifdef SWAPPED_DOUBLE
  43   b = (UBits)(bn.b >> 32);
  44 #else
  45   b = (UBits)bn.b;
  46 #endif
  47 #elif defined(LUA_NUMBER_INT)       || defined(LUA_INT_INT) || \
  48       defined(LUA_NUMBER_LONG)      || defined(LUA_INT_LONG) || \
  49       defined(LUA_NUMBER_LONGLONG)  || defined(LUA_INT_LONGLONG) || \
  50       defined(LUA_NUMBER_LONG_LONG) || defined(LUA_NUMBER_LLONG)
  51   if (sizeof(UBits) == sizeof(lua_Number))
  52     b = bn.b;
  53   else
  54     b = (UBits)(SBits)bn.n;
  55 #elif defined(LUA_NUMBER_FLOAT) || defined(LUA_FLOAT_FLOAT)
  56 #error "A 'float' lua_Number type is incompatible with this library"
  57 #else
  58 #error "Unknown number type, check LUA_NUMBER_*, LUA_FLOAT_*, LUA_INT_* in luaconf.h"
  59 #endif
  60   return b;
  61 }
  62
  63 /* Return bit type. */
  64 #if LUA_VERSION_NUM < 503
  65 #define BRET(b)  lua_pushnumber(L, (lua_Number)(SBits)(b)); return 1;
  66 #else
  67 #define BRET(b)  lua_pushinteger(L, (lua_Integer)(SBits)(b)); return 1;
  68 #endif
  69
  70 static int bit_tobit(lua_State *L) { BRET(barg(L, 1)) }
  71 static int bit_bnot(lua_State *L) { BRET(~barg(L, 1)) }
  72
  73 #define BIT_OP(func, opr) \
  74   static int func(lua_State *L) { int i; UBits b = barg(L, 1); \
  75     for (i = lua_gettop(L); i > 1; i--) { b opr barg(L, i); } BRET(b) }
  76 BIT_OP(bit_band, &=)
  77 BIT_OP(bit_bor, |=)
  78 BIT_OP(bit_bxor, ^=)
  79
  80 #define bshl(b, n)  (b << n)
  81 #define bshr(b, n)  (b >> n)
  82 #define bsar(b, n)  ((SBits)b >> n)
  83 #define brol(b, n)  ((b << n) | (b >> (32-n)))
  84 #define bror(b, n)  ((b << (32-n)) | (b >> n))
  85 #define BIT_SH(func, fn) \
  86   static int func(lua_State *L) { \
  87     UBits b = barg(L, 1); UBits n = barg(L, 2) & 31; BRET(fn(b, n)) }
  88 BIT_SH(bit_lshift, bshl)
  89 BIT_SH(bit_rshift, bshr)
  90 BIT_SH(bit_arshift, bsar)
  91 BIT_SH(bit_rol, brol)
  92 BIT_SH(bit_ror, bror)
  93
  94 static int bit_bswap(lua_State *L)
  95 {
  96   UBits b = barg(L, 1);
  97   b = (b >> 24) | ((b >> 8) & 0xff00) | ((b & 0xff00) << 8) | (b << 24);
  98   BRET(b)
  99 }
 100
 101 static int bit_tohex(lua_State *L)
 102 {
 103   UBits b = barg(L, 1);
 104   SBits n = lua_isnone(L, 2) ? 8 : (SBits)barg(L, 2);
 105   const char *hexdigits = "0123456789abcdef";
 106   char buf[8];
 107   int i;
 108   if (n < 0) { n = -n; hexdigits = "0123456789ABCDEF"; }
 109   if (n > 8) n = 8;
 110   for (i = (int)n; --i >= 0; ) { buf[i] = hexdigits[b & 15]; b >>= 4; }
 111   lua_pushlstring(L, buf, (size_t)n);
 112   return 1;
 113 }
 114
 115 static const struct luaL_Reg bit_funcs[] = {
 116   { "tobit",    bit_tobit },
 117   { "bnot",     bit_bnot },
 118   { "band",     bit_band },
 119   { "bor",      bit_bor },
 120   { "bxor",     bit_bxor },
 121   { "lshift",   bit_lshift },
 122   { "rshift",   bit_rshift },
 123   { "arshift",  bit_arshift },
 124   { "rol",      bit_rol },
 125   { "ror",      bit_ror },
 126   { "bswap",    bit_bswap },
 127   { "tohex",    bit_tohex },
 128   { NULL, NULL }
 129 };
 130
 131 /* Signed right-shifts are implementation-defined per C89/C99.
 132 ** But the de facto standard are arithmetic right-shifts on two's
 133 ** complement CPUs. This behaviour is required here, so test for it.
 134 */
 135 #define BAD_SAR         (bsar(-8, 2) != (SBits)-2)
 136
 137 LUALIB_API int luaopen_bit(lua_State *L)
 138 {
 139   UBits b;
 140 #if LUA_VERSION_NUM < 503
 141   lua_pushnumber(L, (lua_Number)1437217655L);
 142 #else
 143   lua_pushinteger(L, (lua_Integer)1437217655L);
 144 #endif
 145   b = barg(L, -1);
 146   if (b != (UBits)1437217655L || BAD_SAR) {  /* Perform a simple self-test. */
 147     const char *msg = "compiled with incompatible luaconf.h";
 148 #if defined(LUA_NUMBER_DOUBLE) || defined(LUA_FLOAT_DOUBLE)
 149 #ifdef _WIN32
 150     if (b == (UBits)1610612736L)
 151       msg = "use D3DCREATE_FPU_PRESERVE with DirectX";
 152 #endif
 153     if (b == (UBits)1127743488L)
 154       msg = "not compiled with SWAPPED_DOUBLE";
 155 #endif
 156 DIAG_OFF(unreachable-code)
 157     if (BAD_SAR)
 158       msg = "arithmetic right-shift broken";
 159 DIAG_ON(unreachable-code)
 160     luaL_error(L, "bit library self-test failed (%s)", msg);
 161   }
 162
 163   luaL_newlib(L, bit_funcs);
 164   return 1;
 165 }
 166