Document assumptions that are being made to avoid NULL pointer dereferences
[bitcoinplatinum.git] / src / versionbits.h
blob71dc0c85009094567b1829b5d3fb3e7fcafe10bc
1 // Copyright (c) 2016 The Bitcoin Core developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 #ifndef BITCOIN_CONSENSUS_VERSIONBITS
6 #define BITCOIN_CONSENSUS_VERSIONBITS
8 #include "chain.h"
9 #include <map>
11 /** What block version to use for new blocks (pre versionbits) */
12 static const int32_t VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4;
13 /** What bits to set in version for versionbits blocks */
14 static const int32_t VERSIONBITS_TOP_BITS = 0x20000000UL;
15 /** What bitmask determines whether versionbits is in use */
16 static const int32_t VERSIONBITS_TOP_MASK = 0xE0000000UL;
17 /** Total bits available for versionbits */
18 static const int32_t VERSIONBITS_NUM_BITS = 29;
20 enum ThresholdState {
21 THRESHOLD_DEFINED,
22 THRESHOLD_STARTED,
23 THRESHOLD_LOCKED_IN,
24 THRESHOLD_ACTIVE,
25 THRESHOLD_FAILED,
28 // A map that gives the state for blocks whose height is a multiple of Period().
29 // The map is indexed by the block's parent, however, so all keys in the map
30 // will either be nullptr or a block with (height + 1) % Period() == 0.
31 typedef std::map<const CBlockIndex*, ThresholdState> ThresholdConditionCache;
33 struct VBDeploymentInfo {
34 /** Deployment name */
35 const char *name;
36 /** Whether GBT clients can safely ignore this rule in simplified usage */
37 bool gbt_force;
40 struct BIP9Stats {
41 int period;
42 int threshold;
43 int elapsed;
44 int count;
45 bool possible;
48 extern const struct VBDeploymentInfo VersionBitsDeploymentInfo[];
50 /**
51 * Abstract class that implements BIP9-style threshold logic, and caches results.
53 class AbstractThresholdConditionChecker {
54 protected:
55 virtual bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const =0;
56 virtual int64_t BeginTime(const Consensus::Params& params) const =0;
57 virtual int64_t EndTime(const Consensus::Params& params) const =0;
58 virtual int Period(const Consensus::Params& params) const =0;
59 virtual int Threshold(const Consensus::Params& params) const =0;
61 public:
62 BIP9Stats GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const;
63 // Note that the functions below take a pindexPrev as input: they compute information for block B based on its parent.
64 ThresholdState GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
65 int GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
68 struct VersionBitsCache
70 ThresholdConditionCache caches[Consensus::MAX_VERSION_BITS_DEPLOYMENTS];
72 void Clear();
75 ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
76 BIP9Stats VersionBitsStatistics(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos);
77 int VersionBitsStateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
78 uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos);
80 #endif