#! 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;
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