Quick64 (insecure hash function)

<?php
// I needed a quick 64-bit hash function for PHP 5.4.x for a non-cryptographic purpose,
// so I just mixed md4 and md5 (which are both thought to be secure) to get what I wanted
function quick64($input, $raw_output=false) {
  $hash = hash('md5', $input, true) ^ hash('md4', $input, true);
  if($raw_output) {
    return hex2bin(substr( bin2hex($hash), 8, 16));
  } else {
    return substr( bin2hex($hash), 8, 16);
  }
}
/* Usage:
  quick64($input); // Quick hex hash
  quick64($input, 1); // Quick binary hash
*/
# TESTING FUNCTION
for($i = 0; $i < 32; $i++) {
  $j = str_repeat('a', $i);
  echo str_pad($j, 32, ' ', STR_PAD_LEFT)."\t".quick64($j)."\n";
}
# OUTPUT:
                                    5e6a5b355ebc504f
                               a    dd1288ee159d9c19
                              aa    3f8ce95bdf38ab41
                             aaa    f824e54e0497b7b2
                            aaaa    15de74f8ddcc56f9
                           aaaaa    fab5c420ad4f40e6
                          aaaaaa    02ac1089839c6479
                         aaaaaaa    6728193ab2c2171c
                        aaaaaaaa    08a043e87d932e0d
                       aaaaaaaaa    6a0e36a0752609ce
                      aaaaaaaaaa    532c379aa12f300c
                     aaaaaaaaaaa    e83cbdece9fd2d5b
                    aaaaaaaaaaaa    78fb8db510ae9961
                   aaaaaaaaaaaaa    ed603991464c4b87
                  aaaaaaaaaaaaaa    c69794d565bd1f89
                 aaaaaaaaaaaaaaa    1bb356a83fbde039
                aaaaaaaaaaaaaaaa    6b3361be021750cd
               aaaaaaaaaaaaaaaaa    65155d86f62b9795
              aaaaaaaaaaaaaaaaaa    69054b90519c1476
             aaaaaaaaaaaaaaaaaaa    66bdbde7d4392c73
            aaaaaaaaaaaaaaaaaaaa    babd1ccbb5cf1230
           aaaaaaaaaaaaaaaaaaaaa    23b398b4444be296
          aaaaaaaaaaaaaaaaaaaaaa    2aaf21e8d031de3c
         aaaaaaaaaaaaaaaaaaaaaaa    30161c6004c1735e
        aaaaaaaaaaaaaaaaaaaaaaaa    ad6d695db6a950cb
       aaaaaaaaaaaaaaaaaaaaaaaaa    bb670fa603c7093c
      aaaaaaaaaaaaaaaaaaaaaaaaaa    2023a087d5d5eb5d
     aaaaaaaaaaaaaaaaaaaaaaaaaaa    384021e51e1061f2
    aaaaaaaaaaaaaaaaaaaaaaaaaaaa    d036a2ef778a9b69
   aaaaaaaaaaaaaaaaaaaaaaaaaaaaa    34cdf07316a0d641
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa    c6a1a7629a28819c
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa    aaf9ec412e7fea26

Good enough for me. Thought it might be worth sharing