Hi eyepopslikeamosquito. Yes, I've been running tgol2.t found here and it's been running fine. I can comfirm that bit-manipulation is failing with the new tgot2.t. The initial test script did not test for negative $y. Thus, assumed that $y was always positive. The bit-manipulation code will no longer work.

Okay, will comment readers to your post and strike out the bit-manipulation sections. Thank you for posting Extra Test Program tgol.t.

Update: For closure, I tested mapping supporting negative $x and $y. Pack('i2') is faster unless running cperl.

use strict;
use warnings;
use Time::HiRes qw(time);

my ( $x , $y , $iters ) = ( -890394, 100, 5_000_000 );
my ( $xx, $yy, $n );

##
# sub _pack {
#    my ( $x, $y ) = @_;
#    return
#       $x < 0 ? -( abs($x) << 16 | $y ) : $x << 16 | $y;
# }
#
# sub _unpack {
#    my ( $n ) = @_;
#    return $n < 0
#       ? ( -( abs($n) >> 16 ), abs($n) & 0xFFFF )
#       : (        $n  >> 16  ,     $n  & 0xFFFF );
# }
##

bench( "bitops     ", sub {
   # map two integers $x and $y into $n
   # support negative $x only
   for ( 1 .. $iters ) {
      $n = $x < 0 ? -( abs($x) << 16 | $y ) : $x << 16 | $y;
      ( $xx, $yy ) = $n < 0
         ? ( -( abs($n) >> 16 ), abs($n) & 0xFFFF )
         : (        $n  >> 16  ,     $n  & 0xFFFF );
   }
});

##
# sub _pack {
#    my ( $x, $y ) = @_;
#    # bits 0,1 indicate neg flag for $x,$y respectively
#    return
#       ( abs($x) << 18 ) + ( $x < 0 ? 1 : 0 ) +
#       ( abs($y) << 2  ) + ( $y < 0 ? 2 : 0 );
# }
#
# sub _unpack {
#    my ( $n ) = @_;
#    # bits 0,1 indicate neg flag for $x,$y respectively
#    return (
#       $n & 0x1 ? -($n >> 18        ) : $n >> 18,
#       $n & 0x2 ? -($n >> 2 & 0xFFFF) : $n >> 2 & 0xFFFF
#    );
# }
##

bench( "bitops neg ", sub {
   # map two integers $x and $y into $n
   # support negative $x and $y
   for ( 1 .. $iters ) {
      $n = ( abs($x) << 18 ) + ( $x < 0 ? 1 : 0 ) +
           ( abs($y) << 2  ) + ( $y < 0 ? 2 : 0 );
      ( $xx, $yy ) = (
         $n & 0x1 ? -($n >> 18        ) : $n >> 18,
         $n & 0x2 ? -($n >> 2 & 0xFFFF) : $n >> 2 & 0xFFFF
      );
   }
});

bench( "(un)pack ii", sub {
   for ( 1 .. $iters ) {
      $n = pack 'ii', $x, $y;
      ( $xx, $yy ) = unpack 'ii', $n;
   }
});

bench( "(un)pack i2", sub {
   for ( 1 .. $iters ) {
      $n = pack 'i2', $x, $y;
      ( $xx, $yy ) = unpack 'i2', $n;
   }
});

exit;

sub bench {
   my ( $start, $desc, $fcn ) = ( scalar time, @_ );
   $fcn->();
   printf "duration $desc  %0.03f\n", time - $start;
}
[download]

Regards, Mario