Function base64_encode

index.js:425–453

* Encodes a byte array to base64 with up to len bytes of input. * @param {!Array. } b Byte array * @param {number} len Maximum input length * @returns {string} * @inner

(b, len)

 * @inner
 */
function base64_encode(b, len) {
  var off = 0,
    rs = [],
    c1,
    c2;
  if (len <= 0 || len > b.length) throw Error("Illegal len: " + len);
  while (off < len) {
    c1 = b[off++] & 0xff;
    rs.push(BASE64_CODE[(c1 >> 2) & 0x3f]);
    c1 = (c1 & 0x03) << 4;
    if (off >= len) {
      rs.push(BASE64_CODE[c1 & 0x3f]);
      break;
    }
    c2 = b[off++] & 0xff;
    c1 |= (c2 >> 4) & 0x0f;
    rs.push(BASE64_CODE[c1 & 0x3f]);
    c1 = (c2 & 0x0f) << 2;
    if (off >= len) {
      rs.push(BASE64_CODE[c1 & 0x3f]);
      break;
    }
    c2 = b[off++] & 0xff;
    c1 |= (c2 >> 6) & 0x03;
    rs.push(BASE64_CODE[c1 & 0x3f]);
    rs.push(BASE64_CODE[c2 & 0x3f]);
  }
  return rs.join("");
}

/**
 * Decodes a base64 encoded string to up to len bytes of output.