Function luaK_numberK

lib/lua/src/lcode.c:602–619

** Add a float to list of constants and return its index. Floats ** with integral values need a different key, to avoid collision ** with actual integers. To that, we add to the number its smaller ** power-of-two fraction that is still significant in its scale. ** For doubles, that would be 1/2^52. ** (This method is not bulletproof: there may be another float ** with that value, and for floats la

** a duplicate.)
*/
static int luaK_numberK (FuncState *fs, lua_Number r) {
  TValue o;
  lua_Integer ik;
  setfltvalue(&o, r);
  if (!luaV_flttointeger(r, &ik, F2Ieq))  /* not an integral value? */
    return addk(fs, &o, &o);  /* use number itself as key */
  else {  /* must build an alternative key */
    const int nbm = l_floatatt(MANT_DIG);
    const lua_Number q = l_mathop(ldexp)(l_mathop(1.0), -nbm + 1);
    const lua_Number k = (ik == 0) ? q : r + r*q;  /* new key */
    TValue kv;
    setfltvalue(&kv, k);
    /* result is not an integral value, unless value is too large */
    lua_assert(!luaV_flttointeger(k, &ik, F2Ieq) ||
                l_mathop(fabs)(r) >= l_mathop(1e6));
    return addk(fs, &kv, &o);
  }
}


/*