This is an adapted excerpt from a larger script and uses pack in a loop on a bit-shifted value.

use 5.022;
use warnings;

my @netmasks;
my $value = 0xfffffffe;

for my $maskLen ( reverse 0 .. 31 )
{
    unshift @netmasks, pack q{N}, $value;
    $value = do {
       no warnings qw{ portable };
       ( $value <<= 1 ) % 0x100000000;
       };
}

say for map { unpack q{B32}, $_ } @netmasks;
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The output.

00000000000000000000000000000000
10000000000000000000000000000000
11000000000000000000000000000000
11100000000000000000000000000000
11110000000000000000000000000000
11111000000000000000000000000000
11111100000000000000000000000000
11111110000000000000000000000000
11111111000000000000000000000000
11111111100000000000000000000000
11111111110000000000000000000000
11111111111000000000000000000000
11111111111100000000000000000000
11111111111110000000000000000000
11111111111111000000000000000000
11111111111111100000000000000000
11111111111111110000000000000000
11111111111111111000000000000000
11111111111111111100000000000000
11111111111111111110000000000000
11111111111111111111000000000000
11111111111111111111100000000000
11111111111111111111110000000000
11111111111111111111111000000000
11111111111111111111111100000000
11111111111111111111111110000000
11111111111111111111111111000000
11111111111111111111111111100000
11111111111111111111111111110000
11111111111111111111111111111000
11111111111111111111111111111100
11111111111111111111111111111110
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I hope this is helpful.