As you've demonstrated, it fails to split

bacon!!;eggs
[download]

Fix

while (<>) {
    chomp;
    s/\x{00}/\x{00}0/g;
    s/!!/\x{00}1/g;
    s/!;/\x{00}2/g;
    my @a = split /;/;
    for (@a) {
       s/\x{00}2/;/g;
       s/\x{00}1/!/g;
       s/\x{00}0/\x{00}/g;
    }
    ...
}
[download]

I also fixed the inability to have char 00 in the data.