#!/usr/bin/perl -wl
use strict;
use Data::Dumper;

my $N = 4;
my $size = 32;
my $arr = [[1, 2],
           [3, 4],
           [5, 6],
           [7, 8]];

my @C;

foreach my $m (0..2**$N - 1) {

    my $vec = "";
    vec($vec, 0, $size) = $m;
    my @bits = split(//, unpack("B*", $vec));
    splice(@bits, 0, $size - $N);

    # so @bits now contains the binary expansion of $m
    # with exactly $N bits, as you can verify by uncommenting
#    print join "::", @bits;


    $C[ $m ] = 1;
    # now we multiply the $N terms $arr->[i][j]
    # where j is the i-th bit in the binary expansion of $m
    $C[ $m ] *= $arr->[ $_ ][ $bits[$_] ] for 0..$N-1;
}

print Dumper \@C;