text: // Copyright (c) 2016-2018 The Bitcoin Core developers
  // Copyright (c) 2021 The Vivuscoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef VIVUSCOIN_VERSIONBITS_H
  #define VIVUSCOIN_VERSIONBITS_H
  
  #include <chain.h>
  #include <map>
  
  /** What block version to use for new blocks (pre versionbits) */
  static const int32_t VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4;
  /** What bits to set in version for versionbits blocks */
  static const int32_t VERSIONBITS_TOP_BITS = 0x20000000UL;
  /** What bitmask determines whether versionbits is in use */
  static const int32_t VERSIONBITS_TOP_MASK = 0xE0000000UL;
  /** Total bits available for versionbits */
  static const int32_t VERSIONBITS_NUM_BITS = 29;
  
  enum class ThresholdState {
      DEFINED,
      STARTED,
      LOCKED_IN,
      ACTIVE,
      FAILED,
  };
  
  // A map that gives the state for blocks whose height is a multiple of Period().
  // The map is indexed by the block's parent, however, so all keys in the map
  // will either be nullptr or a block with (height + 1) % Period() == 0.
  typedef std::map<const CBlockIndex*, ThresholdState> ThresholdConditionCache;
  
  struct BIP9Stats {
      int period;
      int threshold;
      int elapsed;
      int count;
      bool possible;
  };
  
  /**
   * Abstract class that implements BIP9-style threshold logic, and caches results.
   */
  class AbstractThresholdConditionChecker {
  protected:
      virtual bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const =0;
      virtual int64_t BeginTime(const Consensus::Params& params) const =0;
      virtual int64_t EndTime(const Consensus::Params& params) const =0;
      virtual int Period(const Consensus::Params& params) const =0;
      virtual int Threshold(const Consensus::Params& params) const =0;
  
  public:
      BIP9Stats GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const;
      // Note that the functions below take a pindexPrev as input: they compute information for block B based on its parent.
      ThresholdState GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
      int GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
  };
  
  struct VersionBitsCache
  {
      ThresholdConditionCache caches[Consensus::MAX_VERSION_BITS_DEPLOYMENTS];
  
      void Clear();
  };
  
  ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
  BIP9Stats VersionBitsStatistics(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos);
  int VersionBitsStateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
  uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos);
  
  #endif // VIVUSCOIN_VERSIONBITS_H
  