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1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-2022 The Bitcoin Core developers
3 : : // Distributed under the MIT software license, see the accompanying
4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 : :
6 : : #ifndef BITCOIN_CONSENSUS_PARAMS_H
7 : : #define BITCOIN_CONSENSUS_PARAMS_H
8 : :
9 : : #include <script/verify_flags.h>
10 : : #include <uint256.h>
11 : :
12 : : #include <array>
13 : : #include <chrono>
14 : : #include <limits>
15 : : #include <map>
16 : : #include <vector>
17 : :
18 : : namespace Consensus {
19 : :
20 : : /**
21 : : * A buried deployment is one where the height of the activation has been hardcoded into
22 : : * the client implementation long after the consensus change has activated. See BIP 90.
23 : : */
24 : : enum BuriedDeployment : int16_t {
25 : : // buried deployments get negative values to avoid overlap with DeploymentPos
26 : : DEPLOYMENT_HEIGHTINCB = std::numeric_limits<int16_t>::min(),
27 : : DEPLOYMENT_CLTV,
28 : : DEPLOYMENT_DERSIG,
29 : : DEPLOYMENT_CSV,
30 : : DEPLOYMENT_SEGWIT,
31 : : };
32 : : constexpr bool ValidDeployment(BuriedDeployment dep) { return dep <= DEPLOYMENT_SEGWIT; }
33 : :
34 : : enum DeploymentPos : uint16_t {
35 : : DEPLOYMENT_TESTDUMMY,
36 : : DEPLOYMENT_TAPROOT, // Deployment of Schnorr/Taproot (BIPs 340-342)
37 : : // NOTE: Also add new deployments to VersionBitsDeploymentInfo in deploymentinfo.cpp
38 : : MAX_VERSION_BITS_DEPLOYMENTS
39 : : };
40 : : constexpr bool ValidDeployment(DeploymentPos dep) { return dep < MAX_VERSION_BITS_DEPLOYMENTS; }
41 : :
42 : : /**
43 : : * Struct for each individual consensus rule change using BIP9.
44 : : */
45 : : struct BIP9Deployment {
46 : : /** Bit position to select the particular bit in nVersion. */
47 : : int bit{28};
48 : : /** Start MedianTime for version bits miner confirmation. Can be a date in the past */
49 : : int64_t nStartTime{NEVER_ACTIVE};
50 : : /** Timeout/expiry MedianTime for the deployment attempt. */
51 : : int64_t nTimeout{NEVER_ACTIVE};
52 : : /** If lock in occurs, delay activation until at least this block
53 : : * height. Note that activation will only occur on a retarget
54 : : * boundary.
55 : : */
56 : : int min_activation_height{0};
57 : : /** Period of blocks to check signalling in (usually retarget period, ie params.DifficultyAdjustmentInterval()) */
58 : : uint32_t period{2016};
59 : : /**
60 : : * Minimum blocks including miner confirmation of the total of 2016 blocks in a retargeting period,
61 : : * which is also used for BIP9 deployments.
62 : : * Examples: 1916 for 95%, 1512 for testchains.
63 : : */
64 : : uint32_t threshold{1916};
65 : :
66 : : /** Constant for nTimeout very far in the future. */
67 : : static constexpr int64_t NO_TIMEOUT = std::numeric_limits<int64_t>::max();
68 : :
69 : : /** Special value for nStartTime indicating that the deployment is always active.
70 : : * This is useful for testing, as it means tests don't need to deal with the activation
71 : : * process (which takes at least 3 BIP9 intervals). Only tests that specifically test the
72 : : * behaviour during activation cannot use this. */
73 : : static constexpr int64_t ALWAYS_ACTIVE = -1;
74 : :
75 : : /** Special value for nStartTime indicating that the deployment is never active.
76 : : * This is useful for integrating the code changes for a new feature
77 : : * prior to deploying it on some or all networks. */
78 : : static constexpr int64_t NEVER_ACTIVE = -2;
79 : : };
80 : :
81 : : /**
82 : : * Parameters that influence chain consensus.
83 : : */
84 : : struct Params {
85 : : uint256 hashGenesisBlock;
86 : : int nSubsidyHalvingInterval;
87 : : /**
88 : : * Hashes of blocks that
89 : : * - are known to be consensus valid, and
90 : : * - buried in the chain, and
91 : : * - fail if the default script verify flags are applied.
92 : : */
93 : : std::map<uint256, script_verify_flags> script_flag_exceptions;
94 : : /** Block height and hash at which BIP34 becomes active */
95 : : int BIP34Height;
96 : : uint256 BIP34Hash;
97 : : /** Block height at which BIP65 becomes active */
98 : : int BIP65Height;
99 : : /** Block height at which BIP66 becomes active */
100 : : int BIP66Height;
101 : : /** Block height at which CSV (BIP68, BIP112 and BIP113) becomes active */
102 : : int CSVHeight;
103 : : /** Block height at which Segwit (BIP141, BIP143 and BIP147) becomes active.
104 : : * Note that segwit v0 script rules are enforced on all blocks except the
105 : : * BIP 16 exception blocks. */
106 : : int SegwitHeight;
107 : : /** Don't warn about unknown BIP 9 activations below this height.
108 : : * This prevents us from warning about the CSV and segwit activations. */
109 : : int MinBIP9WarningHeight;
110 : : std::array<BIP9Deployment,MAX_VERSION_BITS_DEPLOYMENTS> vDeployments;
111 : : /** Proof of work parameters */
112 : : uint256 powLimit;
113 : : bool fPowAllowMinDifficultyBlocks;
114 : : /**
115 : : * Enforce BIP94 timewarp attack mitigation. On testnet4 this also enforces
116 : : * the block storm mitigation.
117 : : */
118 : : bool enforce_BIP94;
119 : : bool fPowNoRetargeting;
120 : : int64_t nPowTargetSpacing;
121 : : int64_t nPowTargetTimespan;
122 : 2486 : std::chrono::seconds PowTargetSpacing() const
123 : : {
124 : 2486 : return std::chrono::seconds{nPowTargetSpacing};
125 : : }
126 [ + + + + ]: 1947739 : int64_t DifficultyAdjustmentInterval() const { return nPowTargetTimespan / nPowTargetSpacing; }
[ # # ][ + +
+ + - + ]
127 : : /** The best chain should have at least this much work */
128 : : uint256 nMinimumChainWork;
129 : : /** By default assume that the signatures in ancestors of this block are valid */
130 : : uint256 defaultAssumeValid;
131 : :
132 : : /**
133 : : * If true, witness commitments contain a payload equal to a Bitcoin Script solution
134 : : * to the signet challenge. See BIP325.
135 : : */
136 : : bool signet_blocks{false};
137 : : std::vector<uint8_t> signet_challenge;
138 : :
139 : 1955165 : int DeploymentHeight(BuriedDeployment dep) const
140 : : {
141 [ + + + + : 1955165 : switch (dep) {
+ - ]
142 : 171141 : case DEPLOYMENT_HEIGHTINCB:
143 : 171141 : return BIP34Height;
144 : 257550 : case DEPLOYMENT_CLTV:
145 : 257550 : return BIP65Height;
146 : 257411 : case DEPLOYMENT_DERSIG:
147 : 257411 : return BIP66Height;
148 : 592363 : case DEPLOYMENT_CSV:
149 : 592363 : return CSVHeight;
150 : 676700 : case DEPLOYMENT_SEGWIT:
151 : 676700 : return SegwitHeight;
152 : : } // no default case, so the compiler can warn about missing cases
153 : : return std::numeric_limits<int>::max();
154 : : }
155 : : };
156 : :
157 : : } // namespace Consensus
158 : :
159 : : #endif // BITCOIN_CONSENSUS_PARAMS_H
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