#! perl -slw use strict; use Math::GMPz; my $ZERO = Math::GMPz->new( 0 ); my $ONE = Math::GMPz->new( 1 ); #my $ALLONES = ~ $ZERO; my $ALLONES = (Math::GMPz->new(1) << 128) - 1; my $MASK1 = $ALLONES / 3; my $MASK2 = $ALLONES / 15 * 3; my $MASK3 = $ALLONES / 255; my $MASK4 = $MASK3 * 15; sub bcount { my $v = shift; $v = $v - ( ( $v >> 1 ) & $MASK1 ); $v = ( $v & $MASK2 ) + ( ( $v >> 2 ) & $MASK2 ); $v = ( $v + ( $v >> 4 ) ) & $MASK4; my $c = ( $v * ( $MASK3 ) ) >> 120; return $c; } my $bits = Math::GMPz->new( 0 ); ## set every 3rd bit $bits |= $ONE << $_ for map $_*3+1, 0 .. 42; print $bits; ## count the bits (43) print bcount( $bits ); ## now invert them and count again. (85) print bcount( ~$bits ); __END__ C:\test>gmpz-t.pl 194447066811964836264785489961010406546 4019000903644796537894933644280473643 6698389137940470254461716813547458644