text: /* Bitwise operations library */
  /* (c) Reuben Thomas 2000-2008 */
  /* See README for license */
  
  // Modified by BogdanM for eLua
  
  
  #include "module.h"
  #include <limits.h>
  
  #include "lauxlib.h"
  
  /* FIXME: Assume size_t is an unsigned lua_Integer */
  typedef size_t lua_UInteger;
  #define LUA_UINTEGER_MAX SIZE_MAX
  
  /* Define TOBIT to get a bit value */
  #define TOBIT(L, n)                    \
    (luaL_checkinteger((L), (n)))
  
  /* 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_pushinteger(L, op TOBIT(L, 1));                         \
      return 1;                                                   \
    }
  
  #define VARIADIC(name, op)                      \
    static int bit_ ## name(lua_State *L) {       \
      int n = lua_gettop(L), i;                   \
      lua_Integer w = TOBIT(L, 1);                \
      for (i = 2; i <= n; i++)                    \
        w op TOBIT(L, i);                         \
      lua_pushinteger(L, w);                      \
      return 1;                                   \
    }
  
  #define LOGICAL_SHIFT(name, op)                                         \
    static int bit_ ## name(lua_State *L) {                               \
      lua_pushinteger(L, (lua_UInteger)TOBIT(L, 1) op                     \
                            (unsigned)luaL_checknumber(L, 2));            \
      return 1;                                                           \
    }
  
  #define ARITHMETIC_SHIFT(name, op)                                      \
    static int bit_ ## name(lua_State *L) {                               \
      lua_pushinteger(L, (lua_Integer)TOBIT(L, 1) 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, >>)
  
  // Lua: res = bit( position )
  static int bit_bit( lua_State* L )
  {
    lua_pushinteger( L, ( lua_Integer )( 1 << luaL_checkinteger( L, 1 ) ) );
    return 1;
  }
  
  // Lua: res = isset( value, position )
  static int bit_isset( lua_State* L )
  {
    lua_UInteger val = ( lua_UInteger )luaL_checkinteger( L, 1 );
    unsigned pos = ( unsigned )luaL_checkinteger( L, 2 );
    
    lua_pushboolean( L, val & ( 1 << pos ) ? 1 : 0 );
    return 1;
  }
  
  // Lua: res = isclear( value, position )
  static int bit_isclear( lua_State* L )
  {
    lua_UInteger val = ( lua_UInteger )luaL_checkinteger( L, 1 );
    unsigned pos = ( unsigned )luaL_checkinteger( L, 2 );
    
    lua_pushboolean( L, val & ( 1 << pos ) ? 0 : 1 );
    return 1;
  }
  
  // Lua: res = set( value, pos1, pos2, ... )
  static int bit_set( lua_State* L )
  { 
    lua_UInteger val = ( lua_UInteger )luaL_checkinteger( L, 1 );
    unsigned total = lua_gettop( L ), i;
    
    for( i = 2; i <= total; i ++ )
      val |= 1 << ( unsigned )luaL_checkinteger( L, i );
    lua_pushinteger( L, ( lua_Integer )val );
    return 1;
  }
  
  // Lua: res = clear( value, pos1, pos2, ... )
  static int bit_clear( lua_State* L )
  {
    lua_UInteger val = ( lua_UInteger )luaL_checkinteger( L, 1 );
    unsigned total = lua_gettop( L ), i;
    
    for( i = 2; i <= total; i ++ )
      val &= ~( 1 << ( unsigned )luaL_checkinteger( L, i ) );
    lua_pushinteger( L, ( lua_Integer )val );
    return 1; 
  }
  
  LROT_BEGIN(bit)
    LROT_FUNCENTRY( bnot,    bit_bnot )
    LROT_FUNCENTRY( band,    bit_band )
    LROT_FUNCENTRY( bor,     bit_bor )
    LROT_FUNCENTRY( bxor,    bit_bxor )
    LROT_FUNCENTRY( lshift,  bit_lshift )
    LROT_FUNCENTRY( rshift,  bit_rshift )
    LROT_FUNCENTRY( arshift, bit_arshift )
    LROT_FUNCENTRY( bit,     bit_bit )
    LROT_FUNCENTRY( set,     bit_set )
    LROT_FUNCENTRY( clear,   bit_clear )
    LROT_FUNCENTRY( isset,   bit_isset )
    LROT_FUNCENTRY( isclear, bit_isclear )
  LROT_END(bit, NULL, 0)
  
  NODEMCU_MODULE(BIT, "bit", bit, NULL);
  