#!/usr/bin/perl

use strict;
use warnings;

{
    use integer; #use integer math
    my $x = 123456789;
    my $y = 362436069;
    my $w = 88675123;
    my $z = 521288629;

    sub set_random_seed {
    	$w = shift;
    }

    sub random {
    	my $t = $x ^ ($x << 11);
    	$x = $y;
    	$y = $z;
    	$z = $w;
    	my $rand = $w = ($w ^ ($w >> 19)) ^ ($t ^ ($t >> 8));
    	return $rand % 256; #scale it back to a byte at a time
    }
}

set_random_seed(5);
print map { random(), "n" } 1 .. 10;

use strict;
use warnings;

use List::Util qw(reduce);
use vars qw($a $b);

print 'Taps: ', set_taps( 8, 7, 2, 1 ), "n";
print 'Seed: ', seed_lfsr( 1 ), "n";
print read_lfsr(), "n" for 1..10;

BEGIN {
    my $tap_mask;
    my $lfsr = 0;

    sub read_lfsr {
        $lfsr = ($lfsr >> 1) ^ (-($lfsr & 1) & $tap_mask );

        return $lfsr;
    }

    sub seed_lfsr {
        $lfsr = shift || 0;
        $lfsr &= 0xFF;
    }

    sub set_taps {
        my @taps = @_;

        $tap_mask = reduce { $a + 2**$b } 0, @taps;

        $tap_mask >>= 1;

        $tap_mask &= 0xFF;

        return $tap_mask;
    }
}