scrypt.txt

  /* Basic litecoin algorithm:

     Let data be an 80 byte chunk of work to do.

     sha256_init(midstate)
        . Copies sha256_k  (uint32_t * 64) into midstate.
	
     sha256_transform(midstate, data, 0);
        . The sha256 block compression function.  Accepts a 512 bit input
	.  block and updates state.
	.  This is invariant across nonces, because the nonce is in the
	   second 512 bit (padded) block.  So save it and do
	   computations from there.

	foreach block, increment data[19] - the nonce.

      . input, output, midstate, scratchpad (input =data)

     uint32_t tstate[8] = midstate;
     HMAC_SHA256_80_init(data, tstate, ostate);
     PBKDF2_SHA256_80_128(tstate, ostate, data, X);
     scrypt_core(X);
     PBKDF2_SHA256_128_32(tstate, ostate, X, output);

     This is a successful hash if output[7] <= htarg &&
       fulltest(hash, ptarget) succeeds.
  */