#!/usr/bin/perl
use warnings;
use strict;

# given skew factor and sectors/track,
# return a list of skewed sector numbers.

# skew: skew factor
# sectors: number of sectors (per track)
sub skewlist {
    my ($skew, $sectors) = @_;

    my @a = 1;
    my %seen = (1 => 1);
    for (2..$sectors) {
        my $s = $a[-1] + $skew;
        $s = $skew - ($sectors - $a[-1]) if $s > $sectors;
        $s++ while $seen{$s};
        $seen{$s}++;
        push @a, $s;
    }

    return @a;
}

sub main {
    unless (2 == @ARGV) {
        die "usage: skewgen <skew factor> <number of sectors>";
    }

    my @a = skewlist(@ARGV);

    print "skewlist: @a\n";
}

exit(main());

__END__
$ ./skewgen 4 15
skewlist: 1 5 9 13 2 6 10 14 3 7 11 15 4 8 12

$ ./skewgen 6 26
skewlist: 1 7 13 19 25 5 11 17 23 3 9 15 21 2 8 14 20 26 6 12 18 24 4 
+10 16 22
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