Using the Tie::Cycle module, this can be simplified further ...

use Tie::Cycle;

tie my $whirley, 'Tie::Cycle', [ qw( . o 0 O 0 o ) ];

#   And now for the demonstration ...

++$|;

while (1) {
    print $whirley, "\b";
    sleep 1;
}
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perl -le 'print+unpack("N",pack("B32","00000000000000000000001000000000"))'