/* This function computes the bit position of the highest bit set in the 64-bit value specified by Operand. If Operand is zero, then -1 is returned. Otherwise, a value between 0 and 63 is returned. */
INTN EFIAPI HighBitSet64(IN UINT64 Operand)
/* This function computes the bit position of the highest bit set in the 64-bit value specified by Operand. If Operand is zero, then -1 is returned. Otherwise, a value between 0 and 63 is returned. */
INTN EFIAPI HighBitSet64(IN UINT64 Operand)
{
  if (Operand == (UINT32)Operand) {
    return HighBitSet32 ((UINT32)Operand);
  }
  if (sizeof (UINTN) == sizeof (UINT32)) {
    return HighBitSet32 (((UINT32 *)&Operand)[1]) + 32;
  } else {
    return HighBitSet32 ((UINT32)RShiftU64 (Operand, 32)) + 32;
  }
}