/*
 * Calculate the MD5 of an array of little-endian words, and a bit length.
 */
function wordsToMd5(x, len) {
  /* append padding */
  x[len >> 5] |= 0x80 << len % 32;
  x[(((len + 64) >>> 9) << 4) + 14] = len;

  var i;
  var olda;
  var oldb;
  var oldc;
  var oldd;
  var a = 1732584193;
  var b = -271733879;
  var c = -1732584194;

  var d = 271733878;

  for (i = 0; i < x.length; i += 16) {
    olda = a;
    oldb = b;
    oldc = c;
    oldd = d;

    a = md5ff(a, b, c, d, x[i], 7, -680876936);
    d = md5ff(d, a, b, c, x[i + 1], 12, -389564586);
    c = md5ff(c, d, a, b, x[i + 2], 17, 606105819);
    b = md5ff(b, c, d, a, x[i + 3], 22, -1044525330);
    a = md5ff(a, b, c, d, x[i + 4], 7, -176418897);
    d = md5ff(d, a, b, c, x[i + 5], 12, 1200080426);
    c = md5ff(c, d, a, b, x[i + 6], 17, -1473231341);
    b = md5ff(b, c, d, a, x[i + 7], 22, -45705983);
    a = md5ff(a, b, c, d, x[i + 8], 7, 1770035416);
    d = md5ff(d, a, b, c, x[i + 9], 12, -1958414417);
    c = md5ff(c, d, a, b, x[i + 10], 17, -42063);
    b = md5ff(b, c, d, a, x[i + 11], 22, -1990404162);
    a = md5ff(a, b, c, d, x[i + 12], 7, 1804603682);
    d = md5ff(d, a, b, c, x[i + 13], 12, -40341101);
    c = md5ff(c, d, a, b, x[i + 14], 17, -1502002290);
    b = md5ff(b, c, d, a, x[i + 15], 22, 1236535329);
  }
  return [a, b, c, d];
}

/*
 * These functions implement the four basic operations the algorithm uses.
 */
function md5cmn(q, a, b, x, s, t) {
  return safeAdd(bitRotateLeft(safeAdd(safeAdd(a, q), safeAdd(x, t)), s), b);
}
function md5ff(a, b, c, d, x, s, t) {
  return md5cmn((b & c) | (~b & d), a, b, x, s, t);
}
module.exports = md5;