hash32shiftmult PHP port

hash32shiftmult.php

function hash32shiftmult($key){
  $seed = 0x27d4eb2d; // a prime or an odd constant
  $key = ($key ^ 61) ^ ($key >> 16);
  $key = $key + ($key << 3);
  $key = $key ^ ($key >> 4);
  $key *= $seed;
  $key = $key ^ ($key >> 15);
  return $key;
};

Note that regular collisions are observed from the integer 6990608 and onwards.