That's interesting, but there are reasons other than performance for wanting fix-width integer semantics.

Try coding this with GMP (or any arbitrary precision math):

`#! perl -slw
use strict;
use Math::Int128 qw[int128 uint128];
my $ZERO = uint128( 0 );
my $ONE = uint128( 1 );
my $ALLONES = ~ $ZERO;
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 = uint128( 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>m128.pl
194447066811964836264785489961010406546
43
85
`

Note: I would have supplied a GMPz version, ~~but I couldn't work out how to do it from the docs~~. There seem to be a million ways to initialise a number; a million ways to divide two numbers etc, But not so much when it comes to doing bitwise math.

Update: Here's my attempt at a GMP version of the above. Note that it doesn't just produce the wrong results, but it does so silently:

`#! perl -slw
use strict;
use Math::GMPz;
my $ZERO = Math::GMPz->new( 0 );
my $ONE = Math::GMPz->new( 1 );
my $ALLONES = ~ $ZERO;
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
0
0
`

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

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