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/*
 * This file is part of the Flowee project
 * Copyright (C) 2016 The Bitcoin Core developers
 *
 * 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
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#ifndef FLOWEE_CONSENSUS_VERSIONBITS
#define FLOWEE_CONSENSUS_VERSIONBITS
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#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 ThresholdState {
    THRESHOLD_DEFINED,
    THRESHOLD_STARTED,
    THRESHOLD_LOCKED_IN,
    THRESHOLD_ACTIVE,
    THRESHOLD_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 NULL or a block with (height + 1) % Period() == 0.
typedef std::map<const CBlockIndex*, ThresholdState> ThresholdConditionCache;

/**
 * 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:
    // Note that the function below takes 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;
};

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);
uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos);

#endif