module.exports = function(str) {
  var hash = 5381,
      i    = str.length

  while(i)
    hash = (hash * 33) ^ str.charCodeAt(--i)

  /* JavaScript does bitwise operations (like XOR, above) on 32-bit signed
   * integers. Since we want the results to be always positive, if the high bit
   * is set, unset it and add it back in through (64-bit IEEE) addition. */
  return hash >= 0 ? hash : (hash & 0x7FFFFFFF) + 0x80000000
}