text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2018 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef MICRO_SCRIPT_SIGCACHE_H
  #define MICRO_SCRIPT_SIGCACHE_H
  
  #include <script/interpreter.h>
  
  #include <vector>
  
  // DoS prevention: limit cache size to 32MB (over 1000000 entries on 64-bit
  // systems). Due to how we count cache size, actual memory usage is slightly
  // more (~32.25 MB)
  static const unsigned int DEFAULT_MAX_SIG_CACHE_SIZE = 32;
  // Maximum sig cache size allowed
  static const int64_t MAX_MAX_SIG_CACHE_SIZE = 16384;
  
  class CPubKey;
  
  /**
   * We're hashing a nonce into the entries themselves, so we don't need extra
   * blinding in the set hash computation.
   *
   * This may exhibit platform endian dependent behavior but because these are
   * nonced hashes (random) and this state is only ever used locally it is safe.
   * All that matters is local consistency.
   */
  class SignatureCacheHasher
  {
  public:
      template <uint8_t hash_select>
      uint32_t operator()(const uint256& key) const
      {
          static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available.");
          uint32_t u;
          std::memcpy(&u, key.begin()+4*hash_select, 4);
          return u;
      }
  };
  
  class CachingTransactionSignatureChecker : public TransactionSignatureChecker
  {
  private:
      bool store;
  
  public:
      CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, bool storeIn, PrecomputedTransactionData& txdataIn) : TransactionSignatureChecker(txToIn, nInIn, amountIn, txdataIn), store(storeIn) {}
  
      bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const override;
  };
  
  void InitSignatureCache();
  
  #endif // MICRO_SCRIPT_SIGCACHE_H
  