#use bytes;

$x = "\xAA";
print unpack 'B*', $x;
print " --> ";
$x = chr( ord( $x ) << 1 );
print unpack 'B*', $x;

print "\n---\n";

$x = pack( "C*", 0xAA );
print unpack 'B*', $x;
print " --> ";
$x = pack( "C", unpack( "C", $x ) << 1 );
print unpack 'B*', $x;

print "\n---\n";

##</code><code>##

Character in 'B' format wrapped in unpack at /tmp/j1.pl line 7.
10101010 --> 01010100
---
Character in 'C' format wrapped in pack at /tmp/j1.pl line 14.
10101010 --> 01010100
---