Merge #7575: Minimal BIP9 implementation

8c74ced RPC test for BIP9 warning logic (Suhas Daftuar)
7870deb Test versionbits deployments (Suhas Daftuar)
532cbb2 Add testing of ComputeBlockVersion (Suhas Daftuar)
d23f6c6 Softfork status report in RPC (Pieter Wuille)
732e774 Versionbits tests (Pieter Wuille)
6851107 BIP9 Implementation (Pieter Wuille)

1 files changed, 59 insertions, 0 deletions

diff --git a/src/versionbits.h b/src/versionbits.h
new file mode 100644
index 0000000000..04f4738272
--- /dev/null
+++ b/src/versionbits.h
@@ -0,0 +1,59 @@
+// Copyright (c) 2016 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 BITCOIN_CONSENSUS_VERSIONBITS
+#define BITCOIN_CONSENSUS_VERSIONBITS
+
+#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