use strict;
use warnings;

my $testinput = pack('C/a* a* a*', 
                     (pack 'C*', 1, 2), 
                     (pack 'v*', 3, 4),
                     (pack 'l*', 5, 6));

print join(',', unpack('C/C* v2 l2', $testinput)), "\n";
# gives "1,2,3,4,5,6" which is ok,
# but has the repeat factors for 'v' hardcoded

my $repeat = unpack('C', $testinput);
print join(',', unpack("C/C* v$repeat l$repeat", $testinput)), "\n";
# gives "1,2,3,4,5,6" which is ok, but uses two steps

print join(',', unpack('C/C* @0 CXC /(x[C]) xX /v @0 CXC /((x[C])(x[v])) xX /l', $testinput)), "\n";
# gives "1,2,3,4,5,6" uses one step, but is a bit complex
1;