Calculate the SHA-1 of an array of big-endian words, and a bit length
function binb_sha1 (x, len) {
  // append padding
  x[len >> 5] |= 0x80 << (24 - len % 32);
  x[((len + 64 >> 9) << 4) + 15] = len;

  var w = Array(80);
  var a =  1732584193;
  var b = -271733879;
  var c = -1732584194;
  var d =  271733878;
  var e = -1009589776;
  var t, oa, ob, oc, od, oe, i = 0, j = 0;

  for (i; i < x.length; i += 16) {
    oa = a;
    ob = b;
    oc = c;
    od = d;
    oe = e;

    for (j; j < 80; j++) {
      if (j < 16) w[j] = x[i + j];
      else w[j] = bit_rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
      t = safe_add(safe_add(bit_rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));
      e = d;
      d = c;
      c = bit_rol(b, 30);
      b = a;
      a = t;
    }

    a = safe_add(a, oa);
    b = safe_add(b, ob);
    c = safe_add(c, oc);
    d = safe_add(d, od);
    e = safe_add(e, oe);
  }

  return Array(a, b, c, d, e);
}