#! perl -slw use strict; use Data::Dump qw[ pp ]; my %map; for my $i ( 0 .. 255 ) { my @Q; my @D = split '', unpack 'b8', chr $i; $Q[ 0 ] = $D[ 0 ]; $Q[ 1 ] = $D[ 1 ] ^ $Q[ 0 ]; $Q[ 2 ] = $D[ 2 ] ^ $Q[ 1 ]; $Q[ 3 ] = $D[ 3 ] ^ $Q[ 2 ]; $Q[ 4 ] = $D[ 4 ] ^ $Q[ 3 ]; $Q[ 5 ] = $D[ 5 ] ^ $Q[ 4 ]; $Q[ 6 ] = $D[ 6 ] ^ $Q[ 5 ]; $Q[ 7 ] = $D[ 7 ] ^ $Q[ 6 ]; my $outb = ord pack 'b8', "@Q"; $map{ $i } = $outb; } pp \%map;