text: // Copyright (c) 2017-2018 The Bitcoin Core developers
  // Copyright (c) 2017 The Raven Core developers
  // Copyright (c) 2018 The Liquidcash Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  /*
   * Copyright 2011 ArtForz
   * Copyright 2011-2013 pooler
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2 of the License, or (at your option)
   * any later version.  See COPYING for more details.
   */
  
  #include "miner.h"
  #include "algo-gate-api.h"
  
  #include <string.h>
  #include <inttypes.h>
  
  #if defined(USE_ASM) && defined(__arm__) && defined(__APCS_32__)
  #define EXTERN_SHA256
  #endif
  
  static const uint32_t sha256_h[8] = {
          0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
          0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
  };
  
  static const uint32_t sha256_k[64] = {
          0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
          0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
          0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
          0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
          0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
          0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
          0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
          0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
          0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
          0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
          0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
          0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
          0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
          0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
          0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
          0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
  };
  
  void sha256_init(uint32_t *state)
  {
      memcpy(state, sha256_h, 32);
  }
  
  /* Elementary functions used by SHA256 */
  #define Ch(x, y, z)     ((x & (y ^ z)) ^ z)
  #define Maj(x, y, z)    ((x & (y | z)) | (y & z))
  #define ROTR(x, n)      ((x >> n) | (x << (32 - n)))
  #define S0(x)           (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
  #define S1(x)           (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))
  #define s0(x)           (ROTR(x, 7) ^ ROTR(x, 18) ^ (x >> 3))
  #define s1(x)           (ROTR(x, 17) ^ ROTR(x, 19) ^ (x >> 10))
  
  /* SHA256 round function */
  #define RND(a, b, c, d, e, f, g, h, k) \
  	do { \
  		t0 = h + S1(e) + Ch(e, f, g) + k; \
  		t1 = S0(a) + Maj(a, b, c); \
  		d += t0; \
  		h  = t0 + t1; \
  	} while (0)
  
  /* Adjusted round function for rotating state */
  #define RNDr(S, W, i) \
  	RND(S[(64 - i) % 8], S[(65 - i) % 8], \
  	    S[(66 - i) % 8], S[(67 - i) % 8], \
  	    S[(68 - i) % 8], S[(69 - i) % 8], \
  	    S[(70 - i) % 8], S[(71 - i) % 8], \
  	    W[i] + sha256_k[i])
  
  #ifndef EXTERN_SHA256
  
  /*
   * SHA256 block compression function.  The 256-bit state is transformed via
   * the 512-bit input block to produce a new state.
   */
  void sha256_transform(uint32_t *state, const uint32_t *block, int swap)
  {
      uint32_t W[64];
      uint32_t S[8];
      uint32_t t0, t1;
      int i;
  
      /* 1. Prepare message schedule W. */
      if (swap) {
          for (i = 0; i < 16; i++)
              W[i] = swab32(block[i]);
      } else
          memcpy(W, block, 64);
      for (i = 16; i < 64; i += 2) {
          W[i]   = s1(W[i - 2]) + W[i - 7] + s0(W[i - 15]) + W[i - 16];
          W[i+1] = s1(W[i - 1]) + W[i - 6] + s0(W[i - 14]) + W[i - 15];
      }
  
      /* 2. Initialize working variables. */
      memcpy(S, state, 32);
  
      /* 3. Mix. */
      RNDr(S, W,  0);
      RNDr(S, W,  1);
      RNDr(S, W,  2);
      RNDr(S, W,  3);
      RNDr(S, W,  4);
      RNDr(S, W,  5);
      RNDr(S, W,  6);
      RNDr(S, W,  7);
      RNDr(S, W,  8);
      RNDr(S, W,  9);
      RNDr(S, W, 10);
      RNDr(S, W, 11);
      RNDr(S, W, 12);
      RNDr(S, W, 13);
      RNDr(S, W, 14);
      RNDr(S, W, 15);
      RNDr(S, W, 16);
      RNDr(S, W, 17);
      RNDr(S, W, 18);
      RNDr(S, W, 19);
      RNDr(S, W, 20);
      RNDr(S, W, 21);
      RNDr(S, W, 22);
      RNDr(S, W, 23);
      RNDr(S, W, 24);
      RNDr(S, W, 25);
      RNDr(S, W, 26);
      RNDr(S, W, 27);
      RNDr(S, W, 28);
      RNDr(S, W, 29);
      RNDr(S, W, 30);
      RNDr(S, W, 31);
      RNDr(S, W, 32);
      RNDr(S, W, 33);
      RNDr(S, W, 34);
      RNDr(S, W, 35);
      RNDr(S, W, 36);
      RNDr(S, W, 37);
      RNDr(S, W, 38);
      RNDr(S, W, 39);
      RNDr(S, W, 40);
      RNDr(S, W, 41);
      RNDr(S, W, 42);
      RNDr(S, W, 43);
      RNDr(S, W, 44);
      RNDr(S, W, 45);
      RNDr(S, W, 46);
      RNDr(S, W, 47);
      RNDr(S, W, 48);
      RNDr(S, W, 49);
      RNDr(S, W, 50);
      RNDr(S, W, 51);
      RNDr(S, W, 52);
      RNDr(S, W, 53);
      RNDr(S, W, 54);
      RNDr(S, W, 55);
      RNDr(S, W, 56);
      RNDr(S, W, 57);
      RNDr(S, W, 58);
      RNDr(S, W, 59);
      RNDr(S, W, 60);
      RNDr(S, W, 61);
      RNDr(S, W, 62);
      RNDr(S, W, 63);
  
      /* 4. Mix local working variables into global state */
      for (i = 0; i < 8; i++)
          state[i] += S[i];
  }
  
  #endif /* EXTERN_SHA256 */
  
  
  static const uint32_t sha256d_hash1[16] = {
  	0x00000000, 0x00000000, 0x00000000, 0x00000000,
  	0x00000000, 0x00000000, 0x00000000, 0x00000000,
  	0x80000000, 0x00000000, 0x00000000, 0x00000000,
  	0x00000000, 0x00000000, 0x00000000, 0x00000100
  };
  
  static void sha256d_80_swap(uint32_t *hash, const uint32_t *data)
  {
      uint32_t S[16];
      int i;
  
      sha256_init(S);
      sha256_transform(S, data, 0);
      sha256_transform(S, data + 16, 0);
      memcpy(S + 8, sha256d_hash1 + 8, 32);
      sha256_init(hash);
      sha256_transform(hash, S, 0);
      for (i = 0; i < 8; i++)
          hash[i] = swab32(hash[i]);
  }
  
  extern void sha256d(unsigned char *hash, const unsigned char *data, int len)
  {
      uint32_t S[16], T[16];
      int i, r;
  
      sha256_init(S);
      for (r = len; r > -9; r -= 64) {
          if (r < 64)
              memset(T, 0, 64);
          memcpy(T, data + len - r, r > 64 ? 64 : (r < 0 ? 0 : r));
          if (r >= 0 && r < 64)
              ((unsigned char *)T)[r] = 0x80;
          for (i = 0; i < 16; i++)
              T[i] = be32dec(T + i);
          if (r < 56)
              T[15] = 8 * len;
          sha256_transform(S, T, 0);
      }
      memcpy(S + 8, sha256d_hash1 + 8, 32);
      sha256_init(T);
      sha256_transform(T, S, 0);
      for (i = 0; i < 8; i++)
          be32enc((uint32_t *)hash + i, T[i]);
  }
  
  static inline void sha256d_preextend(uint32_t *W)
  {
      W[16] = s1(W[14]) + W[ 9] + s0(W[ 1]) + W[ 0];
      W[17] = s1(W[15]) + W[10] + s0(W[ 2]) + W[ 1];
      W[18] = s1(W[16]) + W[11]             + W[ 2];
      W[19] = s1(W[17]) + W[12] + s0(W[ 4]);
      W[20] =             W[13] + s0(W[ 5]) + W[ 4];
      W[21] =             W[14] + s0(W[ 6]) + W[ 5];
      W[22] =             W[15] + s0(W[ 7]) + W[ 6];
      W[23] =             W[16] + s0(W[ 8]) + W[ 7];
      W[24] =             W[17] + s0(W[ 9]) + W[ 8];
      W[25] =                     s0(W[10]) + W[ 9];
      W[26] =                     s0(W[11]) + W[10];
      W[27] =                     s0(W[12]) + W[11];
      W[28] =                     s0(W[13]) + W[12];
      W[29] =                     s0(W[14]) + W[13];
      W[30] =                     s0(W[15]) + W[14];
      W[31] =                     s0(W[16]) + W[15];
  }
  
  static inline void sha256d_prehash(uint32_t *S, const uint32_t *W)
  {
      uint32_t t0, t1;
      RNDr(S, W, 0);
      RNDr(S, W, 1);
      RNDr(S, W, 2);
  }
  
  #ifdef EXTERN_SHA256
  
  void sha256d_ms(uint32_t *hash, uint32_t *W,
  	const uint32_t *midstate, const uint32_t *prehash);
  
  #else
  
  static inline void sha256d_ms(uint32_t *hash, uint32_t *W,
  	const uint32_t *midstate, const uint32_t *prehash)
  {
      uint32_t S[64];
      uint32_t t0, t1;
      int i;
  
      S[18] = W[18];
      S[19] = W[19];
      S[20] = W[20];
      S[22] = W[22];
      S[23] = W[23];
      S[24] = W[24];
      S[30] = W[30];
      S[31] = W[31];
  
      W[18] += s0(W[3]);
      W[19] += W[3];
      W[20] += s1(W[18]);
      W[21]  = s1(W[19]);
      W[22] += s1(W[20]);
      W[23] += s1(W[21]);
      W[24] += s1(W[22]);
      W[25]  = s1(W[23]) + W[18];
      W[26]  = s1(W[24]) + W[19];
      W[27]  = s1(W[25]) + W[20];
      W[28]  = s1(W[26]) + W[21];
      W[29]  = s1(W[27]) + W[22];
      W[30] += s1(W[28]) + W[23];
      W[31] += s1(W[29]) + W[24];
      for (i = 32; i < 64; i += 2) {
          W[i]   = s1(W[i - 2]) + W[i - 7] + s0(W[i - 15]) + W[i - 16];
          W[i+1] = s1(W[i - 1]) + W[i - 6] + s0(W[i - 14]) + W[i - 15];
      }
  
      memcpy(S, prehash, 32);
  
      RNDr(S, W,  3);
      RNDr(S, W,  4);
      RNDr(S, W,  5);
      RNDr(S, W,  6);
      RNDr(S, W,  7);
      RNDr(S, W,  8);
      RNDr(S, W,  9);
      RNDr(S, W, 10);
      RNDr(S, W, 11);
      RNDr(S, W, 12);
      RNDr(S, W, 13);
      RNDr(S, W, 14);
      RNDr(S, W, 15);
      RNDr(S, W, 16);
      RNDr(S, W, 17);
      RNDr(S, W, 18);
      RNDr(S, W, 19);
      RNDr(S, W, 20);
      RNDr(S, W, 21);
      RNDr(S, W, 22);
      RNDr(S, W, 23);
      RNDr(S, W, 24);
      RNDr(S, W, 25);
      RNDr(S, W, 26);
      RNDr(S, W, 27);
      RNDr(S, W, 28);
      RNDr(S, W, 29);
      RNDr(S, W, 30);
      RNDr(S, W, 31);
      RNDr(S, W, 32);
      RNDr(S, W, 33);
      RNDr(S, W, 34);
      RNDr(S, W, 35);
      RNDr(S, W, 36);
      RNDr(S, W, 37);
      RNDr(S, W, 38);
      RNDr(S, W, 39);
      RNDr(S, W, 40);
      RNDr(S, W, 41);
      RNDr(S, W, 42);
      RNDr(S, W, 43);
      RNDr(S, W, 44);
      RNDr(S, W, 45);
      RNDr(S, W, 46);
      RNDr(S, W, 47);
      RNDr(S, W, 48);
      RNDr(S, W, 49);
      RNDr(S, W, 50);
      RNDr(S, W, 51);
      RNDr(S, W, 52);
      RNDr(S, W, 53);
      RNDr(S, W, 54);
      RNDr(S, W, 55);
      RNDr(S, W, 56);
      RNDr(S, W, 57);
      RNDr(S, W, 58);
      RNDr(S, W, 59);
      RNDr(S, W, 60);
      RNDr(S, W, 61);
      RNDr(S, W, 62);
      RNDr(S, W, 63);
  
      for (i = 0; i < 8; i++)
          S[i] += midstate[i];
  
      W[18] = S[18];
      W[19] = S[19];
      W[20] = S[20];
      W[22] = S[22];
      W[23] = S[23];
      W[24] = S[24];
      W[30] = S[30];
      W[31] = S[31];
  
      memcpy(S + 8, sha256d_hash1 + 8, 32);
      S[16] = s1(sha256d_hash1[14]) + sha256d_hash1[ 9] + s0(S[ 1]) + S[ 0];
      S[17] = s1(sha256d_hash1[15]) + sha256d_hash1[10] + s0(S[ 2]) + S[ 1];
      S[18] = s1(S[16]) + sha256d_hash1[11] + s0(S[ 3]) + S[ 2];
      S[19] = s1(S[17]) + sha256d_hash1[12] + s0(S[ 4]) + S[ 3];
      S[20] = s1(S[18]) + sha256d_hash1[13] + s0(S[ 5]) + S[ 4];
      S[21] = s1(S[19]) + sha256d_hash1[14] + s0(S[ 6]) + S[ 5];
      S[22] = s1(S[20]) + sha256d_hash1[15] + s0(S[ 7]) + S[ 6];
      S[23] = s1(S[21]) + S[16] + s0(sha256d_hash1[ 8]) + S[ 7];
      S[24] = s1(S[22]) + S[17] + s0(sha256d_hash1[ 9]) + sha256d_hash1[ 8];
      S[25] = s1(S[23]) + S[18] + s0(sha256d_hash1[10]) + sha256d_hash1[ 9];
      S[26] = s1(S[24]) + S[19] + s0(sha256d_hash1[11]) + sha256d_hash1[10];
      S[27] = s1(S[25]) + S[20] + s0(sha256d_hash1[12]) + sha256d_hash1[11];
      S[28] = s1(S[26]) + S[21] + s0(sha256d_hash1[13]) + sha256d_hash1[12];
      S[29] = s1(S[27]) + S[22] + s0(sha256d_hash1[14]) + sha256d_hash1[13];
      S[30] = s1(S[28]) + S[23] + s0(sha256d_hash1[15]) + sha256d_hash1[14];
      S[31] = s1(S[29]) + S[24] + s0(S[16])             + sha256d_hash1[15];
      for (i = 32; i < 60; i += 2) {
          S[i]   = s1(S[i - 2]) + S[i - 7] + s0(S[i - 15]) + S[i - 16];
          S[i+1] = s1(S[i - 1]) + S[i - 6] + s0(S[i - 14]) + S[i - 15];
      }
      S[60] = s1(S[58]) + S[53] + s0(S[45]) + S[44];
  
      sha256_init(hash);
  
      RNDr(hash, S,  0);
      RNDr(hash, S,  1);
      RNDr(hash, S,  2);
      RNDr(hash, S,  3);
      RNDr(hash, S,  4);
      RNDr(hash, S,  5);
      RNDr(hash, S,  6);
      RNDr(hash, S,  7);
      RNDr(hash, S,  8);
      RNDr(hash, S,  9);
      RNDr(hash, S, 10);
      RNDr(hash, S, 11);
      RNDr(hash, S, 12);
      RNDr(hash, S, 13);
      RNDr(hash, S, 14);
      RNDr(hash, S, 15);
      RNDr(hash, S, 16);
      RNDr(hash, S, 17);
      RNDr(hash, S, 18);
      RNDr(hash, S, 19);
      RNDr(hash, S, 20);
      RNDr(hash, S, 21);
      RNDr(hash, S, 22);
      RNDr(hash, S, 23);
      RNDr(hash, S, 24);
      RNDr(hash, S, 25);
      RNDr(hash, S, 26);
      RNDr(hash, S, 27);
      RNDr(hash, S, 28);
      RNDr(hash, S, 29);
      RNDr(hash, S, 30);
      RNDr(hash, S, 31);
      RNDr(hash, S, 32);
      RNDr(hash, S, 33);
      RNDr(hash, S, 34);
      RNDr(hash, S, 35);
      RNDr(hash, S, 36);
      RNDr(hash, S, 37);
      RNDr(hash, S, 38);
      RNDr(hash, S, 39);
      RNDr(hash, S, 40);
      RNDr(hash, S, 41);
      RNDr(hash, S, 42);
      RNDr(hash, S, 43);
      RNDr(hash, S, 44);
      RNDr(hash, S, 45);
      RNDr(hash, S, 46);
      RNDr(hash, S, 47);
      RNDr(hash, S, 48);
      RNDr(hash, S, 49);
      RNDr(hash, S, 50);
      RNDr(hash, S, 51);
      RNDr(hash, S, 52);
      RNDr(hash, S, 53);
      RNDr(hash, S, 54);
      RNDr(hash, S, 55);
      RNDr(hash, S, 56);
  
      hash[2] += hash[6] + S1(hash[3]) + Ch(hash[3], hash[4], hash[5])
                 + S[57] + sha256_k[57];
      hash[1] += hash[5] + S1(hash[2]) + Ch(hash[2], hash[3], hash[4])
                 + S[58] + sha256_k[58];
      hash[0] += hash[4] + S1(hash[1]) + Ch(hash[1], hash[2], hash[3])
                 + S[59] + sha256_k[59];
      hash[7] += hash[3] + S1(hash[0]) + Ch(hash[0], hash[1], hash[2])
                 + S[60] + sha256_k[60]
                 + sha256_h[7];
  }
  
  #endif /* EXTERN_SHA256 */
  
  #ifdef HAVE_SHA256_4WAY
  
  void sha256d_ms_4way(uint32_t *hash,  uint32_t *data,
  	const uint32_t *midstate, const uint32_t *prehash);
  
  static inline int scanhash_sha256d_4way(int thr_id, struct work *work,
               uint32_t max_nonce, uint64_t *hashes_done)
  {
          uint32_t *pdata = work->data;
          uint32_t *ptarget = work->target;
  
  	uint32_t _ALIGN(128) data[4 * 64];
  	uint32_t _ALIGN(32) hash[4 * 8];
  	uint32_t _ALIGN(32) midstate[4 * 8];
  	uint32_t _ALIGN(32) prehash[4 * 8];
  	uint32_t n = pdata[19] - 1;
  	const uint32_t first_nonce = pdata[19];
  	const uint32_t Htarg = ptarget[7];
  	int i, j;
  
  	memcpy(data, pdata + 16, 64);
  	sha256d_preextend(data);
  	for (i = 31; i >= 0; i--)
  		for (j = 0; j < 4; j++)
  			data[i * 4 + j] = data[i];
  
  	sha256_init(midstate);
  	sha256_transform(midstate, pdata, 0);
  	memcpy(prehash, midstate, 32);
  	sha256d_prehash(prehash, pdata + 16);
  	for (i = 7; i >= 0; i--) {
  		for (j = 0; j < 4; j++) {
  			midstate[i * 4 + j] = midstate[i];
  			prehash[i * 4 + j] = prehash[i];
  		}
  	}
  
  	do {
  		for (i = 0; i < 4; i++)
  			data[4 * 3 + i] = ++n;
  
  		sha256d_ms_4way(hash, data, midstate, prehash);
  
  		for (i = 0; i < 4; i++) {
  			if (swab32(hash[4 * 7 + i]) <= Htarg) {
  				pdata[19] = data[4 * 3 + i];
  				sha256d_80_swap(hash, pdata);
  				if (fulltest(hash, ptarget)) {
  					*hashes_done = n - first_nonce + 1;
  					return 1;
  				}
  			}
  		}
  	} while (n < max_nonce && !work_restart[thr_id].restart);
  
  	*hashes_done = n - first_nonce + 1;
  	pdata[19] = n;
  	return 0;
  }
  
  #endif /* HAVE_SHA256_4WAY */
  
  #ifdef HAVE_SHA256_8WAY
  
  void sha256d_ms_8way(uint32_t *hash,  uint32_t *data,
  	const uint32_t *midstate, const uint32_t *prehash);
  
  static inline int scanhash_sha256d_8way(int thr_id, struct work *work,
                                uint32_t max_nonce, uint64_t *hashes_done)
  {
          uint32_t *pdata = work->data;
          uint32_t *ptarget = work->target;
  
  	uint32_t _ALIGN(128) data[8 * 64];
  	uint32_t _ALIGN(32)  hash[8 * 8];
  	uint32_t _ALIGN(32)  midstate[8 * 8];
  	uint32_t _ALIGN(32)  prehash[8 * 8];
  	uint32_t n = pdata[19] - 1;
  	const uint32_t first_nonce = pdata[19];
  	const uint32_t Htarg = ptarget[7];
  	int i, j;
  
  	memcpy(data, pdata + 16, 64);
  	sha256d_preextend(data);
  	for (i = 31; i >= 0; i--)
  		for (j = 0; j < 8; j++)
  			data[i * 8 + j] = data[i];
  
  	sha256_init(midstate);
  	sha256_transform(midstate, pdata, 0);
  	memcpy(prehash, midstate, 32);
  	sha256d_prehash(prehash, pdata + 16);
  	for (i = 7; i >= 0; i--) {
  		for (j = 0; j < 8; j++) {
  			midstate[i * 8 + j] = midstate[i];
  			prehash[i * 8 + j] = prehash[i];
  		}
  	}
  
  	do {
  		for (i = 0; i < 8; i++)
  			data[8 * 3 + i] = ++n;
  
  		sha256d_ms_8way(hash, data, midstate, prehash);
  
  		for (i = 0; i < 8; i++) {
  			if (swab32(hash[8 * 7 + i]) <= Htarg) {
  				pdata[19] = data[8 * 3 + i];
  				sha256d_80_swap(hash, pdata);
  				if (fulltest(hash, ptarget)) {
  					*hashes_done = n - first_nonce + 1;
  					return 1;
  				}
  			}
  		}
  	} while (n < max_nonce && !work_restart[thr_id].restart);
  
  	*hashes_done = n - first_nonce + 1;
  	pdata[19] = n;
  	return 0;
  }
  
  #endif /* HAVE_SHA256_8WAY */
  
  int scanhash_sha256d(int thr_id, struct work *work,
                       uint32_t max_nonce, uint64_t *hashes_done)
  {
      uint32_t *pdata = work->data;
      uint32_t *ptarget = work->target;
      uint32_t _ALIGN(128) data[64];
      uint32_t _ALIGN(32) hash[8];
      uint32_t _ALIGN(32) midstate[8];
      uint32_t _ALIGN(32) prehash[8];
      uint32_t n = pdata[19] - 1;
      const uint32_t first_nonce = pdata[19];
      const uint32_t Htarg = ptarget[7];
  
  #ifdef HAVE_SHA256_8WAY
      if (sha256_use_8way())
  		return scanhash_sha256d_8way(thr_id, work,
  			max_nonce, hashes_done);
  #endif
  #ifdef HAVE_SHA256_4WAY
      if (sha256_use_4way())
  		return scanhash_sha256d_4way(thr_id, work,
  			max_nonce, hashes_done);
  #endif
  
      memcpy(data, pdata + 16, 64);
      sha256d_preextend(data);
  
      sha256_init(midstate);
      sha256_transform(midstate, pdata, 0);
      memcpy(prehash, midstate, 32);
      sha256d_prehash(prehash, pdata + 16);
  
      do {
          data[3] = ++n;
          sha256d_ms(hash, data, midstate, prehash);
          if (unlikely(swab32(hash[7]) <= Htarg)) {
              pdata[19] = data[3];
              sha256d_80_swap(hash, pdata);
              if (fulltest(hash, ptarget)) {
                  *hashes_done = n - first_nonce + 1;
                  return 1;
              }
          }
      } while (likely(n < max_nonce && !work_restart[thr_id].restart));
  
      *hashes_done = n - first_nonce + 1;
      pdata[19] = n;
      return 0;
  }
  
  bool register_sha256d_algo( algo_gate_t* gate )
  {
      gate->scanhash = (void*)&scanhash_sha256d;
      gate->hash_alt = (void*)&sha256d;
      gate->hash     = (void*)&sha256d;
      return true;
  };
  