#!/usr/bin/perl

use warnings;
use strict;

sub makeBitstream {
    my $lenarr = $#_ + 1;
    if ($lenarr % 2) {
        die "Uneven number of elements in array.";
    }
    my @l = ();
    my $i;
    my $x = 0;
    while ($x < $lenarr / 2) {
        push(@l, shift(@_));
        $x++;
    }
    my @v = @_;
    my $bitstream = "";
    for ($i=0; $i<=$#v; $i++) {
        my $s = "%0" . $l[$i] . "b";
        $bitstream .= sprintf("$s", $v[$i]);
    }
    return $bitstream;
}

sub makeThreeBytes {
    my $bitstream = shift;
    my $i;
    my @listOfBytes = (substr($bitstream, 0, 8),
                       substr($bitstream, 8, 8),
                       substr($bitstream, 16, 8));
    for ($i=0; $i<=$#listOfBytes;$i++) {
        $listOfBytes[$i] = oct("0b". $listOfBytes[$i]);
    }
    return \@listOfBytes;
}

sub makeChecksum {
    my $listOfBytes = shift;
    my $checksum = 0;
    foreach my $i (@{$listOfBytes}) {
        $checksum += $i;
    }
    # print "checksum1: $checksum\n";
    $checksum -= 512 if ($checksum > 511);
    $checksum -= 256 if ($checksum > 255);
    $checksum -= 128 if ($checksum > 127);
    # print "checksum1: $checksum\n";
    return $checksum;
}

sub makeCommandStream {
    my @params = @_;
    my @a = ((5, 1, 10, 8), @params);
    my $bitstream = makeBitstream(@a);
    my $listOfBytes = makeThreeBytes($bitstream);
    push @params, makeChecksum($listOfBytes);
    my @b = ((5, 1, 10, 8, 8), @params);
    return makeBitstream(@b);
}

print makeCommandStream(2, 0, 64, 2) . "\n";