It could be painfully obvious (just suggested as an alternative):

if ($value =~ /^(\d+)d$/i) {
    $day = $1;
}
elsif ($value =~ /^(\d+)d\s+(\d+)h$/i) {
    $day = $1;
    $hour = $2;
}
elsif ($value =~ /^(\d+)h$/i) {
    $hour = $1;
}
else {
    print "Hork!\n";
}
[download]

What exactly do you want out of this?