Which bit is set? (inverse of (1<<$value) operator)

[wirito]

Hello fellow monks, I'm storing values in a bitwise manner for speed up comparations. I can have 0 or more values in the 0..8 range, so I can store it this way:

$bits |= (1<<$val)

When 1 single bit is set I want to retrive the original $val. So currently I have this implemented:

if( unpack( "%16B*", pack("n", $bits)) == 1 ) {
  my $ret = 0;
  while (!($bits & 0x1)) {
    $ret++;
    $bits >>= 1;
  };
  return $ret;
};

I don't know why, but the while loop seems ugly. Could you enligthen me with a more perlish way to do this? PS: I hope the title is not so much confusing.