Argument "B" isn't numeric in numeric bitwise xor (^) at 1.pl line 10.

##</code><code>##

use feature qw( bitwise );

##</code><code>##

my $stoval = "$pckval" ^. 0x80;

##</code><code>##

$stoval = "B" ^. 0x80;  # $stoval = [s28]  -  Expecting [194]
$stohex = "0x" . (unpack 'H16', "s28");  # $stohex = [0x733238]  -  Expecting [0xc2]

##</code><code>##

my $stoval = $pckval ^ "\x80";
# or
my $stoval = $pckval ^ chr 0x80;
# or
my $stoval = $pckval ^ pack 'C', 0x80;
# ...