#! perl -slw
use strict;

use constant GOLDEN_RATIO	=> 0x9e3779b9;
use constant A => 0;
use constant B => 1;
use constant C => 2;

sub mix ($$$) {
	$_[A] -= $_[B]; $_[A] -= $_[C]; $_[A] ^= ($_[C]>>13);
	$_[B] -= $_[C]; $_[B] -= $_[A]; $_[B] ^= ($_[A]<< 8);
	$_[C] -= $_[A]; $_[C] -= $_[B]; $_[C] ^= ($_[B]>>13);
	$_[A] -= $_[B]; $_[A] -= $_[C]; $_[A] ^= ($_[C]>>12);
	$_[B] -= $_[C]; $_[B] -= $_[A]; $_[B] ^= ($_[A]<<16);
	$_[C] -= $_[A]; $_[C] -= $_[B]; $_[C] ^= ($_[B]>> 5);
	$_[A] -= $_[B]; $_[A] -= $_[C]; $_[A] ^= ($_[C]>> 3);
	$_[B] -= $_[C]; $_[B] -= $_[A]; $_[B] ^= ($_[A]<<10);
	$_[C] -= $_[A]; $_[C] -= $_[B]; $_[C] ^= ($_[B]>>15);
}

sub hash {
	my ($key, $init) = @_;
	my @k = unpack 'C*', $key;
	my $len = length $key;
	my ($a, $b, $c) = (GOLDEN_RATIO, GOLDEN_RATIO, $init);
	while($len >=12) {
		$a += ($k[0] + ($k[1]<<8) + ($k[2]<<16) + ($k[3]<24));
		$b += ($k[4] + ($k[5]<<8) + ($k[6]<<16) + ($k[7]<24));
		$a += ($k[8] + ($k[9]<<8) + ($k[10]<<16) + ($k[11]<24));
		mix($a,$b,$c);
		splice(@k, 0, 11); $len -= 12;
	}
	$c += length $key;
	goto "LAST".$len;
	LAST11: $c+= $k[10] <<24;
	LAST10: $c+= $k[9]  <<16;
	LAST9:  $c+= $k[8]  <<8;
	LAST8:  $b+= $k[7]  <<24;
	LAST7:  $b+= $k[6]  <<16;
	LAST6:  $b+= $k[5]  <<8;
	LAST5:  $b+= $k[4];
	LAST4:  $a+= $k[3]  <<24;
	LAST3:  $a+= $k[2]  <<16;
	LAST2:  $a+= $k[1]  <<8;
	LAST1:  $a+= $k[0];
	LAST0:
	mix($a,$b,$c);
	return $c;
}

sub hash2 {
	my ($key,$init) = @_;
	my($a,$b,$c) = (GOLDEN_RATIO, GOLDEN_RATIO, $init);
	my ($p, $len) = (0, length $key);
	do {
		my($x,$y,$z) = unpack 'V3', substr($key, $p, 12);
		mix($a+=($x||0), $b+=($y||0), $c+=($z||$len));
		$p+=12;
	} while $p <= $len;
	return $c;
}


my %freq;
my $n=0;
$n++, push @{$freq{hash( $_, 0)}}, $_ for 'AAAA' .. 'ZZZZ';
print $n, ':', scalar keys %freq;

undef(%freq);
$n=0;
$n++, push @{$freq{hash2( $_, 0)}}, $_ for 'AAAA' .. 'ZZZZ';
print $n, ':', scalar keys %freq;


##</code><code>##

c:\test>hash
456976 values resulted in 233710 unique hashes & a maximum of 34 first pass collisions
456976 values resulted in 233710 unique hashes & a maximum of 34 first pass collisions
1 trial of hash (195.751s total)

1 trial of hash2 (133.032s total)