my $byte = 129;                          # 0b10000001 = 129
my $most_significant_5  = $byte >> 3;    # 0b10000    =  16
my $least_significant_3 = $byte & 0x7;   # 0b     001 =   1

##</code><code>##

                             is a simplification of
              ----------------------------------------------------
$byte >> 3    ( $byte & 0xFF ) >> 3    or    ( $byte >> 3 ) & 0x1F
$byte & 0x7   ( $byte & 0x7  ) >> 0    or    ( $byte >> 0 ) & 0x7