code: public void reset() {
          super.reset();
  
          /* SHA-512 initial hash value
           * The first 64 bits of the fractional parts of the square roots
           * of the first eight prime numbers
           */
          H1 = 0x6a09e667f3bcc908L;
          H2 = 0xbb67ae8584caa73bL;
          H3 = 0x3c6ef372fe94f82bL;
          H4 = 0xa54ff53a5f1d36f1L;
          H5 = 0x510e527fade682d1L;
          H6 = 0x9b05688c2b3e6c1fL;
          H7 = 0x1f83d9abfb41bd6bL;
          H8 = 0x5be0cd19137e2179L;
      }
docs: reset the chaining variables