Function luaO_codeparam

src/lobject.cpp:72–87

** Encodes 'p'% as a floating-point byte, represented as (eeeexxxx). ** The exponent is represented using excess-7. Mimicking IEEE 754, the ** representation normalizes the number when possible, assuming an extra ** 1 before the mantissa (xxxx) and adding one to the exponent (eeee) ** to signal that. So, the real value is (1xxxx) * 2^(eeee - 7 - 1) if ** eeee != 0, and (xxxx) * 2^-7 otherwise (sub

** eeee != 0, and (xxxx) * 2^-7 otherwise (subnormal numbers).
*/
lu_byte luaO_codeparam (unsigned int p) {
  if (p >= (cast(lu_mem, 0x1F) << (0xF - 7 - 1)) * 100u)  /* overflow? */
    return 0xFF;  /* return maximum value */
  else {
    p = (cast(l_uint32, p) * 128 + 99) / 100;  /* round up the division */
    if (p < 0x10) {  /* subnormal number? */
      /* exponent bits are already zero; nothing else to do */
      return cast_byte(p);
    }
    else {  /* p >= 0x10 implies ceil(log2(p + 1)) >= 5 */
      /* preserve 5 bits in 'p' */
      unsigned log = luaO_ceillog2(p + 1) - 5u;
      return cast_byte(((p >> log) - 0x10) | ((log + 1) << 4));
    }
  }
}


/*