srecord MD5(long a, long b) {
  // md5 is the digest, not the data being checksummed
  *(byte[] md5) {
    assertEquals("MD5 digest", 16, l(md5));
    a = longFromBytes_bigEndian(md5, 0);
    b = longFromBytes_bigEndian(md5, 8);
  }
  
  *(S md5) {
    this(parseHexBytes(md5));
  }
  
  toString { ret "MD5=" + longToHex(a) + longToHex(b); }
}