text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2014 The Bitcoin developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "miner.h"
  
  #include "core.h"
  #include "main.h"
  #include "net.h"
  #ifdef ENABLE_WALLET
  #include "wallet.h"
  #endif
  //////////////////////////////////////////////////////////////////////////////
  //
  // BitcoinMiner
  //
  
  int static FormatHashBlocks(void* pbuffer, unsigned int len)
  {
      unsigned char* pdata = (unsigned char*)pbuffer;
      unsigned int blocks = 1 + ((len + 8) / 64);
      unsigned char* pend = pdata + 64 * blocks;
      memset(pdata + len, 0, 64 * blocks - len);
      pdata[len] = 0x80;
      unsigned int bits = len * 8;
      pend[-1] = (bits >> 0) & 0xff;
      pend[-2] = (bits >> 8) & 0xff;
      pend[-3] = (bits >> 16) & 0xff;
      pend[-4] = (bits >> 24) & 0xff;
      return blocks;
  }
  
  static const unsigned int pSHA256InitState[8] =
  {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};
  
  void SHA256Transform(void* pstate, void* pinput, const void* pinit)
  {
      SHA256_CTX ctx;
      unsigned char data[64];
  
      SHA256_Init(&ctx);
  
      for (int i = 0; i < 16; i++)
          ((uint32_t*)data)[i] = ByteReverse(((uint32_t*)pinput)[i]);
  
      for (int i = 0; i < 8; i++)
          ctx.h[i] = ((uint32_t*)pinit)[i];
  
      SHA256_Update(&ctx, data, sizeof(data));
      for (int i = 0; i < 8; i++)
          ((uint32_t*)pstate)[i] = ctx.h[i];
  }
  
  // Some explaining would be appreciated
  class COrphan
  {
  public:
      const CTransaction* ptx;
      set<uint256> setDependsOn;
      double dPriority;
      double dFeePerKb;
  
      COrphan(const CTransaction* ptxIn)
      {
          ptx = ptxIn;
          dPriority = dFeePerKb = 0;
      }
  
      void print() const
      {
          LogPrintf("COrphan(hash=%s, dPriority=%.1f, dFeePerKb=%.1f)\n",
                 ptx->GetHash().ToString(), dPriority, dFeePerKb);
          BOOST_FOREACH(uint256 hash, setDependsOn)
              LogPrintf("   setDependsOn %s\n", hash.ToString());
      }
  };
  
  
  uint64_t nLastBlockTx = 0;
  uint64_t nLastBlockSize = 0;
  
  // We want to sort transactions by priority and fee, so:
  typedef boost::tuple<double, double, const CTransaction*> TxPriority;
  class TxPriorityCompare
  {
      bool byFee;
  public:
      TxPriorityCompare(bool _byFee) : byFee(_byFee) { }
      bool operator()(const TxPriority& a, const TxPriority& b)
      {
          if (byFee)
          {
              if (a.get<1>() == b.get<1>())
                  return a.get<0>() < b.get<0>();
              return a.get<1>() < b.get<1>();
          }
          else
          {
              if (a.get<0>() == b.get<0>())
                  return a.get<1>() < b.get<1>();
              return a.get<0>() < b.get<0>();
          }
      }
  };
  
  CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
  {
      // Create new block
      auto_ptr<CBlockTemplate> pblocktemplate(new CBlockTemplate());
      if(!pblocktemplate.get())
          return NULL;
      CBlock *pblock = &pblocktemplate->block; // pointer for convenience
  
      // Create coinbase tx
      CTransaction txNew;
      txNew.vin.resize(1);
      txNew.vin[0].prevout.SetNull();
      txNew.vout.resize(1);
      txNew.vout[0].scriptPubKey = scriptPubKeyIn;
  
      // Add our coinbase tx as first transaction
      pblock->vtx.push_back(txNew);
      pblocktemplate->vTxFees.push_back(-1); // updated at end
      pblocktemplate->vTxSigOps.push_back(-1); // updated at end
  
      // Largest block you're willing to create:
      unsigned int nBlockMaxSize = GetArg("-blockmaxsize", DEFAULT_BLOCK_MAX_SIZE);
      // Limit to betweeen 1K and MAX_BLOCK_SIZE-1K for sanity:
      nBlockMaxSize = std::max((unsigned int)1000, std::min((unsigned int)(MAX_BLOCK_SIZE-1000), nBlockMaxSize));
  
      // How much of the block should be dedicated to high-priority transactions,
      // included regardless of the fees they pay
      unsigned int nBlockPrioritySize = GetArg("-blockprioritysize", DEFAULT_BLOCK_PRIORITY_SIZE);
      nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
  
      // Minimum block size you want to create; block will be filled with free transactions
      // until there are no more or the block reaches this size:
      unsigned int nBlockMinSize = GetArg("-blockminsize", DEFAULT_BLOCK_MIN_SIZE);
      nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);
  
      // Collect memory pool transactions into the block
      int64_t nFees = 0;
      {
          LOCK2(cs_main, mempool.cs);
          CBlockIndex* pindexPrev = chainActive.Tip();
          CCoinsViewCache view(*pcoinsTip, true);
  
          // Priority order to process transactions
          list<COrphan> vOrphan; // list memory doesn't move
          map<uint256, vector<COrphan*> > mapDependers;
          bool fPrintPriority = GetBoolArg("-printpriority", false);
  
          // This vector will be sorted into a priority queue:
          vector<TxPriority> vecPriority;
          vecPriority.reserve(mempool.mapTx.size());
          for (map<uint256, CTxMemPoolEntry>::iterator mi = mempool.mapTx.begin();
               mi != mempool.mapTx.end(); ++mi)
          {
              const CTransaction& tx = mi->second.GetTx();
              if (tx.IsCoinBase() || !IsFinalTx(tx, pindexPrev->nHeight + 1))
                  continue;
  
              COrphan* porphan = NULL;
              double dPriority = 0;
              int64_t nTotalIn = 0;
              bool fMissingInputs = false;
              BOOST_FOREACH(const CTxIn& txin, tx.vin)
              {
                  // Read prev transaction
                  if (!view.HaveCoins(txin.prevout.hash))
                  {
                      // This should never happen; all transactions in the memory
                      // pool should connect to either transactions in the chain
                      // or other transactions in the memory pool.
                      if (!mempool.mapTx.count(txin.prevout.hash))
                      {
                          LogPrintf("ERROR: mempool transaction missing input\n");
                          if (fDebug) assert("mempool transaction missing input" == 0);
                          fMissingInputs = true;
                          if (porphan)
                              vOrphan.pop_back();
                          break;
                      }
  
                      // Has to wait for dependencies
                      if (!porphan)
                      {
                          // Use list for automatic deletion
                          vOrphan.push_back(COrphan(&tx));
                          porphan = &vOrphan.back();
                      }
                      mapDependers[txin.prevout.hash].push_back(porphan);
                      porphan->setDependsOn.insert(txin.prevout.hash);
                      nTotalIn += mempool.mapTx[txin.prevout.hash].GetTx().vout[txin.prevout.n].nValue;
                      continue;
                  }
                  const CCoins &coins = view.GetCoins(txin.prevout.hash);
  
                  int64_t nValueIn = coins.vout[txin.prevout.n].nValue;
                  nTotalIn += nValueIn;
  
                  int nConf = pindexPrev->nHeight - coins.nHeight + 1;
  
                  dPriority += (double)nValueIn * nConf;
              }
              if (fMissingInputs) continue;
  
              // Priority is sum(valuein * age) / modified_txsize
              unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
              dPriority = tx.ComputePriority(dPriority, nTxSize);
  
              // This is a more accurate fee-per-kilobyte than is used by the client code, because the
              // client code rounds up the size to the nearest 1K. That's good, because it gives an
              // incentive to create smaller transactions.
              double dFeePerKb =  double(nTotalIn-tx.GetValueOut()) / (double(nTxSize)/1000.0);
  
              if (porphan)
              {
                  porphan->dPriority = dPriority;
                  porphan->dFeePerKb = dFeePerKb;
              }
              else
                  vecPriority.push_back(TxPriority(dPriority, dFeePerKb, &mi->second.GetTx()));
          }
  
          // Collect transactions into block
          uint64_t nBlockSize = 1000;
          uint64_t nBlockTx = 0;
          int nBlockSigOps = 100;
          bool fSortedByFee = (nBlockPrioritySize <= 0);
  
          TxPriorityCompare comparer(fSortedByFee);
          std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
  
          while (!vecPriority.empty())
          {
              // Take highest priority transaction off the priority queue:
              double dPriority = vecPriority.front().get<0>();
              double dFeePerKb = vecPriority.front().get<1>();
              const CTransaction& tx = *(vecPriority.front().get<2>());
  
              std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
              vecPriority.pop_back();
  
              // Size limits
              unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
              if (nBlockSize + nTxSize >= nBlockMaxSize)
                  continue;
  
              // Legacy limits on sigOps:
              unsigned int nTxSigOps = GetLegacySigOpCount(tx);
              if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                  continue;
  
              // Skip free transactions if we're past the minimum block size:
              if (fSortedByFee && (dFeePerKb < CTransaction::nMinRelayTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
                  continue;
  
              // Prioritize by fee once past the priority size or we run out of high-priority
              // transactions:
              if (!fSortedByFee &&
                  ((nBlockSize + nTxSize >= nBlockPrioritySize) || !AllowFree(dPriority)))
              {
                  fSortedByFee = true;
                  comparer = TxPriorityCompare(fSortedByFee);
                  std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
              }
  
              if (!view.HaveInputs(tx))
                  continue;
  
              int64_t nTxFees = view.GetValueIn(tx)-tx.GetValueOut();
  
              nTxSigOps += GetP2SHSigOpCount(tx, view);
              if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                  continue;
  
              CValidationState state;
              if (!CheckInputs(tx, state, view, true, SCRIPT_VERIFY_P2SH))
                  continue;
  
              CTxUndo txundo;
              uint256 hash = tx.GetHash();
              UpdateCoins(tx, state, view, txundo, pindexPrev->nHeight+1, hash);
  
              // Added
              pblock->vtx.push_back(tx);
              pblocktemplate->vTxFees.push_back(nTxFees);
              pblocktemplate->vTxSigOps.push_back(nTxSigOps);
              nBlockSize += nTxSize;
              ++nBlockTx;
              nBlockSigOps += nTxSigOps;
              nFees += nTxFees;
  
              if (fPrintPriority)
              {
                  LogPrintf("priority %.1f feeperkb %.1f txid %s\n",
                         dPriority, dFeePerKb, tx.GetHash().ToString());
              }
  
              // Add transactions that depend on this one to the priority queue
              if (mapDependers.count(hash))
              {
                  BOOST_FOREACH(COrphan* porphan, mapDependers[hash])
                  {
                      if (!porphan->setDependsOn.empty())
                      {
                          porphan->setDependsOn.erase(hash);
                          if (porphan->setDependsOn.empty())
                          {
                              vecPriority.push_back(TxPriority(porphan->dPriority, porphan->dFeePerKb, porphan->ptx));
                              std::push_heap(vecPriority.begin(), vecPriority.end(), comparer);
                          }
                      }
                  }
              }
          }
  
          nLastBlockTx = nBlockTx;
          nLastBlockSize = nBlockSize;
          LogPrintf("CreateNewBlock(): total size %u\n", nBlockSize);
  
          pblock->vtx[0].vout[0].nValue = GetBlockValue(pindexPrev->nHeight+1, nFees);
          pblocktemplate->vTxFees[0] = -nFees;
  
          // Fill in header
          pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
          UpdateTime(*pblock, pindexPrev);
          pblock->nBits          = GetNextWorkRequired(pindexPrev, pblock);
          pblock->nNonce         = 0;
          pblock->vtx[0].vin[0].scriptSig = CScript() << OP_0 << OP_0;
          pblocktemplate->vTxSigOps[0] = GetLegacySigOpCount(pblock->vtx[0]);
  
          CBlockIndex indexDummy(*pblock);
          indexDummy.pprev = pindexPrev;
          indexDummy.nHeight = pindexPrev->nHeight + 1;
          CCoinsViewCache viewNew(*pcoinsTip, true);
          CValidationState state;
          if (!ConnectBlock(*pblock, state, &indexDummy, viewNew, true))
              throw std::runtime_error("CreateNewBlock() : ConnectBlock failed");
      }
  
      return pblocktemplate.release();
  }
  
  void IncrementExtraNonce(CBlock* pblock, CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
  {
      // Update nExtraNonce
      static uint256 hashPrevBlock;
      if (hashPrevBlock != pblock->hashPrevBlock)
      {
          nExtraNonce = 0;
          hashPrevBlock = pblock->hashPrevBlock;
      }
      ++nExtraNonce;
      unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
      pblock->vtx[0].vin[0].scriptSig = (CScript() << nHeight << CBigNum(nExtraNonce)) + COINBASE_FLAGS;
      assert(pblock->vtx[0].vin[0].scriptSig.size() <= 100);
  
      pblock->hashMerkleRoot = pblock->BuildMerkleTree();
  }
  
  
  void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1)
  {
      //
      // Pre-build hash buffers
      //
      struct
      {
          struct unnamed2
          {
              int nVersion;
              uint256 hashPrevBlock;
              uint256 hashMerkleRoot;
              unsigned int nTime;
              unsigned int nBits;
              unsigned int nNonce;
          }
          block;
          unsigned char pchPadding0[64];
          uint256 hash1;
          unsigned char pchPadding1[64];
      }
      tmp;
      memset(&tmp, 0, sizeof(tmp));
  
      tmp.block.nVersion       = pblock->nVersion;
      tmp.block.hashPrevBlock  = pblock->hashPrevBlock;
      tmp.block.hashMerkleRoot = pblock->hashMerkleRoot;
      tmp.block.nTime          = pblock->nTime;
      tmp.block.nBits          = pblock->nBits;
      tmp.block.nNonce         = pblock->nNonce;
  
      FormatHashBlocks(&tmp.block, sizeof(tmp.block));
      FormatHashBlocks(&tmp.hash1, sizeof(tmp.hash1));
  
      // Byte swap all the input buffer
      for (unsigned int i = 0; i < sizeof(tmp)/4; i++)
          ((unsigned int*)&tmp)[i] = ByteReverse(((unsigned int*)&tmp)[i]);
  
      // Precalc the first half of the first hash, which stays constant
      SHA256Transform(pmidstate, &tmp.block, pSHA256InitState);
  
      memcpy(pdata, &tmp.block, 128);
      memcpy(phash1, &tmp.hash1, 64);
  }
  
  #ifdef ENABLE_WALLET
  //////////////////////////////////////////////////////////////////////////////
  //
  // Internal miner
  //
  double dHashesPerSec = 0.0;
  int64_t nHPSTimerStart = 0;
  
  //
  // ScanHash scans nonces looking for a hash with at least some zero bits.
  // It operates on big endian data.  Caller does the byte reversing.
  // All input buffers are 16-byte aligned.  nNonce is usually preserved
  // between calls, but periodically or if nNonce is 0xffff0000 or above,
  // the block is rebuilt and nNonce starts over at zero.
  //
  unsigned int static ScanHash_CryptoPP(char* pmidstate, char* pdata, char* phash1, char* phash, unsigned int& nHashesDone)
  {
      unsigned int& nNonce = *(unsigned int*)(pdata + 12);
      for (;;)
      {
          // Crypto++ SHA256
          // Hash pdata using pmidstate as the starting state into
          // pre-formatted buffer phash1, then hash phash1 into phash
          nNonce++;
          SHA256Transform(phash1, pdata, pmidstate);
          SHA256Transform(phash, phash1, pSHA256InitState);
  
          // Return the nonce if the hash has at least some zero bits,
          // caller will check if it has enough to reach the target
          if (((unsigned short*)phash)[14] == 0)
              return nNonce;
  
          // If nothing found after trying for a while, return -1
          if ((nNonce & 0xffff) == 0)
          {
              nHashesDone = 0xffff+1;
              return (unsigned int) -1;
          }
          if ((nNonce & 0xfff) == 0)
              boost::this_thread::interruption_point();
      }
  }
  
  CBlockTemplate* CreateNewBlockWithKey(CReserveKey& reservekey)
  {
      CPubKey pubkey;
      if (!reservekey.GetReservedKey(pubkey))
          return NULL;
  
      CScript scriptPubKey = CScript() << pubkey << OP_CHECKSIG;
      return CreateNewBlock(scriptPubKey);
  }
  
  bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey)
  {
      uint256 hash = pblock->GetHash();
      uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
  
      if (hash > hashTarget)
          return false;
  
      //// debug print
      LogPrintf("ZetacoinMiner:\n");
      LogPrintf("proof-of-work found  \n  hash: %s  \ntarget: %s\n", hash.GetHex(), hashTarget.GetHex());
      pblock->print();
      LogPrintf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue));
  
      // Found a solution
      {
          LOCK(cs_main);
          if (pblock->hashPrevBlock != chainActive.Tip()->GetBlockHash())
              return error("ZetacoinMiner : generated block is stale");
  
          // Remove key from key pool
          reservekey.KeepKey();
  
          // Track how many getdata requests this block gets
          {
              LOCK(wallet.cs_wallet);
              wallet.mapRequestCount[pblock->GetHash()] = 0;
          }
  
          // Process this block the same as if we had received it from another node
          CValidationState state;
          if (!ProcessBlock(state, NULL, pblock))
              return error("ZetacoinMiner : ProcessBlock, block not accepted");
      }
  
      return true;
  }
  
  void static BitcoinMiner(CWallet *pwallet)
  {
      LogPrintf("ZetacoinMiner started\n");
      SetThreadPriority(THREAD_PRIORITY_LOWEST);
      RenameThread("bitcoin-miner");
  
      // Each thread has its own key and counter
      CReserveKey reservekey(pwallet);
      unsigned int nExtraNonce = 0;
  
      try { while (true) {
          if (Params().NetworkID() != CChainParams::REGTEST) {
              // Busy-wait for the network to come online so we don't waste time mining
              // on an obsolete chain. In regtest mode we expect to fly solo.
              while (vNodes.empty())
                  MilliSleep(1000);
          }
  
          //
          // Create new block
          //
          unsigned int nTransactionsUpdatedLast = mempool.GetTransactionsUpdated();
          CBlockIndex* pindexPrev = chainActive.Tip();
  
          auto_ptr<CBlockTemplate> pblocktemplate(CreateNewBlockWithKey(reservekey));
          if (!pblocktemplate.get())
              return;
          CBlock *pblock = &pblocktemplate->block;
          IncrementExtraNonce(pblock, pindexPrev, nExtraNonce);
  
          LogPrintf("Running ZetacoinMiner with %u transactions in block (%u bytes)\n", pblock->vtx.size(),
                 ::GetSerializeSize(*pblock, SER_NETWORK, PROTOCOL_VERSION));
  
          //
          // Pre-build hash buffers
          //
          char pmidstatebuf[32+16]; char* pmidstate = alignup<16>(pmidstatebuf);
          char pdatabuf[128+16];    char* pdata     = alignup<16>(pdatabuf);
          char phash1buf[64+16];    char* phash1    = alignup<16>(phash1buf);
  
          FormatHashBuffers(pblock, pmidstate, pdata, phash1);
  
          unsigned int& nBlockTime = *(unsigned int*)(pdata + 64 + 4);
          unsigned int& nBlockBits = *(unsigned int*)(pdata + 64 + 8);
          unsigned int& nBlockNonce = *(unsigned int*)(pdata + 64 + 12);
  
  
          //
          // Search
          //
          int64_t nStart = GetTime();
          uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
          uint256 hashbuf[2];
          uint256& hash = *alignup<16>(hashbuf);
          while (true)
          {
              unsigned int nHashesDone = 0;
              unsigned int nNonceFound;
  
              // Crypto++ SHA256
              nNonceFound = ScanHash_CryptoPP(pmidstate, pdata + 64, phash1,
                                              (char*)&hash, nHashesDone);
  
              // Check if something found
              if (nNonceFound != (unsigned int) -1)
              {
                  for (unsigned int i = 0; i < sizeof(hash)/4; i++)
                      ((unsigned int*)&hash)[i] = ByteReverse(((unsigned int*)&hash)[i]);
  
                  if (hash <= hashTarget)
                  {
                      // Found a solution
                      pblock->nNonce = ByteReverse(nNonceFound);
                      assert(hash == pblock->GetHash());
  
                      SetThreadPriority(THREAD_PRIORITY_NORMAL);
                      CheckWork(pblock, *pwallet, reservekey);
                      SetThreadPriority(THREAD_PRIORITY_LOWEST);
  
                      // In regression test mode, stop mining after a block is found. This
                      // allows developers to controllably generate a block on demand.
                      if (Params().NetworkID() == CChainParams::REGTEST)
                          throw boost::thread_interrupted();
  
                      break;
                  }
              }
  
              // Meter hashes/sec
              static int64_t nHashCounter;
              if (nHPSTimerStart == 0)
              {
                  nHPSTimerStart = GetTimeMillis();
                  nHashCounter = 0;
              }
              else
                  nHashCounter += nHashesDone;
              if (GetTimeMillis() - nHPSTimerStart > 4000)
              {
                  static CCriticalSection cs;
                  {
                      LOCK(cs);
                      if (GetTimeMillis() - nHPSTimerStart > 4000)
                      {
                          dHashesPerSec = 1000.0 * nHashCounter / (GetTimeMillis() - nHPSTimerStart);
                          nHPSTimerStart = GetTimeMillis();
                          nHashCounter = 0;
                          static int64_t nLogTime;
                          if (GetTime() - nLogTime > 30 * 60)
                          {
                              nLogTime = GetTime();
                              LogPrintf("hashmeter %6.0f khash/s\n", dHashesPerSec/1000.0);
                          }
                      }
                  }
              }
  
              // Check for stop or if block needs to be rebuilt
              boost::this_thread::interruption_point();
              if (vNodes.empty() && Params().NetworkID() != CChainParams::REGTEST)
                  break;
              if (nBlockNonce >= 0xffff0000)
                  break;
              if (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLast && GetTime() - nStart > 60)
                  break;
              if (pindexPrev != chainActive.Tip())
                  break;
  
              // Update nTime every few seconds
              UpdateTime(*pblock, pindexPrev);
              nBlockTime = ByteReverse(pblock->nTime);
              if (TestNet())
              {
                  // Changing pblock->nTime can change work required on testnet:
                  nBlockBits = ByteReverse(pblock->nBits);
                  hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
              }
          }
      } }
      catch (boost::thread_interrupted)
      {
          LogPrintf("ZetacoinMiner terminated\n");
          throw;
      }
  }
  
  void GenerateBitcoins(bool fGenerate, CWallet* pwallet, int nThreads)
  {
      static boost::thread_group* minerThreads = NULL;
  
      if (nThreads < 0) {
          if (Params().NetworkID() == CChainParams::REGTEST)
              nThreads = 1;
          else
              nThreads = boost::thread::hardware_concurrency();
      }
  
      if (minerThreads != NULL)
      {
          minerThreads->interrupt_all();
          delete minerThreads;
          minerThreads = NULL;
      }
  
      if (nThreads == 0 || !fGenerate)
          return;
  
      minerThreads = new boost::thread_group();
      for (int i = 0; i < nThreads; i++)
          minerThreads->create_thread(boost::bind(&BitcoinMiner, pwallet));
  }
  
  #endif
  
  