Optimization of difficulty adjustment strategy

Optimization of difficulty adjustment strategy

src/chain.h

@@ -17,6 +17,20 @@
 #include <vector>
 #include <string.h>
 
+/**
+ * Maximum amount of time that a block timestamp is allowed to exceed the
+ * current network-adjusted time before the block will be accepted.
+ */
+static const int64_t BCH_MAX_FUTURE_BLOCK_TIME = 2 * 60 * 60;  //T<600  should not use it
+
+/**
+ * Timestamp window used as a grace period by code that compares external
+ * timestamps (such as timestamps passed to RPCs, or wallet key creation times)
+ * to block timestamps. This should be set at least as high as
+ * BCH_MAX_FUTURE_BLOCK_TIME.
+ */
+static const int64_t TIMESTAMP_WINDOW = BCH_MAX_FUTURE_BLOCK_TIME;
+
 class CBlockFileInfo {
 public:
     //!< number of blocks stored in file

src/chainparams.cpp

@@ -24,6 +24,7 @@
 
 #include "base58.h"
 #include <boost/assign/list_of.hpp>
+#include <limits>
 
 #include "chainparamsseeds.h"
 
@@ -121,12 +122,14 @@ class CMainParams : public CChainParams {
         consensus.powLimit = uint256S("0007ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
         consensus.powLimitLegacy = uint256S("00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
 
-        //based on https://github.com/BTCGPU/BTCGPU/issues/78
-        consensus.nPowAveragingWindow = 30;
-        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nPowAveragingWindow);
-        consensus.nPowMaxAdjustDown = 32;
-        consensus.nPowMaxAdjustUp = 16;
+        consensus.nDigishieldAveragingWindow = 30;
+        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nDigishieldAveragingWindow);
+        consensus.nDigishieldMaxAdjustDown = 32;
+        consensus.nDigishieldMaxAdjustUp = 16;
 
+        consensus.nZawyLwmaAveragingWindow = 60;
+        consensus.CDYMaxFutureBlockTime = 7 * 2 * 60; //
+
         // two weeks
         consensus.nPowTargetTimespanLegacy = 14 * 24 * 60 * 60;
         consensus.nPowTargetSpacing = 10 * 60;
@@ -172,6 +175,11 @@ class CMainParams : public CChainParams {
 
         //  hard fork-----add by hmc
         consensus.cdyHeight = 512666;
+
+
+
+        consensus.CDYZawyLWMAHeight = 573123;
+
         consensus.BitcoinPostforkBlock = uint256S("0000000000000000007b746068bd08ba4089f97636690e9dc758774e7db21f17");	// 512666 block hash
         consensus.BitcoinPostforkTime = 1515799972;
 
@@ -303,14 +311,15 @@ class CTestNetParams : public CChainParams {
         consensus.antiReplayOpReturnSunsetHeight = 1250000;
         consensus.antiReplayOpReturnCommitment = GetAntiReplayCommitment();
         consensus.powLimit = uint256S("0007ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
-		consensus.powLimitLegacy = uint256S("00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
+	consensus.powLimitLegacy = uint256S("00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
 
-        //based on https://github.com/BTCGPU/BTCGPU/issues/78
-        consensus.nPowAveragingWindow = 30;
-        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nPowAveragingWindow);
-        consensus.nPowMaxAdjustDown = 32;
-        consensus.nPowMaxAdjustUp = 16;
+        consensus.nDigishieldAveragingWindow= 30;
+        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nDigishieldAveragingWindow);
+        consensus.nDigishieldMaxAdjustDown = 32;
+        consensus.nDigishieldMaxAdjustUp = 16;
 
+        consensus.nZawyLwmaAveragingWindow = 60;
+        consensus.CDYMaxFutureBlockTime = 7 * 2 * 60; // 14 mins
         // two weeks
         consensus.nPowTargetTimespanLegacy = 14 * 24 * 60 * 60;
         consensus.nPowTargetSpacing = 10 * 60;
@@ -355,6 +364,8 @@ class CTestNetParams : public CChainParams {
 
         //  hard fork-----add by hmc
         consensus.cdyHeight = 201601;
+
+        consensus.CDYZawyLWMAHeight = 201681; 
         consensus.BitcoinPostforkBlock = uint256S("00000000d16d6c2aecc7436eea0c54a53741fee9abf265606aa465d6fd3f3d8a"); // block 201601
         consensus.BitcoinPostforkTime = 1393815074;
 
@@ -379,7 +390,7 @@ class CTestNetParams : public CChainParams {
 
         // use different default
         nDefaultPort = 18367;
-		nBitcoinDefaultPort = 18333;
+	nBitcoinDefaultPort = 18333;
         nPruneAfterHeight = 1000;
         const size_t N = 200, K = 9;
         BOOST_STATIC_ASSERT(equihash_parameters_acceptable(N, K));
@@ -399,9 +410,7 @@ class CTestNetParams : public CChainParams {
         vFixedSeeds.clear();
         vSeeds.clear();
         // nodes with support for servicebits filtering should be at the top
-        // Bitcoin ABC seeder
         vSeeds.push_back(CDNSSeedData("bitcoincandy.one", "testnet-seed.bitcoincandy.one", true));
-
         base58Prefixes[PUBKEY_ADDRESS] = std::vector<uint8_t>(1, 111);
         base58Prefixes[SCRIPT_ADDRESS] = std::vector<uint8_t>(1, 196);
         base58Prefixes[SECRET_KEY] = std::vector<uint8_t>(1, 239);
@@ -457,14 +466,15 @@ class CRegTestParams : public CChainParams {
         consensus.powLimit = uint256S("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
 		consensus.powLimitLegacy = uint256S("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
 
-        //based on https://github.com/BTCGPU/BTCGPU/issues/78
-        consensus.nPowAveragingWindow = 30;
-        //assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nPowAveragingWindow);
-        consensus.nPowMaxAdjustDown = 32;
-        consensus.nPowMaxAdjustUp = 16;
+        consensus.nDigishieldAveragingWindow = 30;
+        consensus.nDigishieldMaxAdjustDown = 32;
+        consensus.nDigishieldMaxAdjustUp = 16;
 
-        // two weeks
-        consensus.nPowTargetTimespanLegacy = 14 * 24 * 60 * 60;
+        consensus.nZawyLwmaAveragingWindow = 45;
+        consensus.nZawyLwmaAjustedWeight = 13632;
+        consensus.CDYMaxFutureBlockTime = 7 * 10 * 60; // 70 mins
+
+        consensus.nPowTargetTimespanLegacy = 14 * 24 * 60 * 60; // two weeks
         consensus.nPowTargetSpacing = 10 * 60;
         consensus.nPowTargetSpacingCDY = 2 * 60;
         consensus.fPowAllowMinDifficultyBlocks = true;
@@ -497,7 +507,9 @@ class CRegTestParams : public CChainParams {
 
         // Nov, 13 hard fork is always on on regtest.
         consensus.daaHeight = 2250;
-
+
+        consensus.CDYZawyLWMAHeight = -1;
+
         diskMagic[0] = 0xfa;
         diskMagic[1] = 0xbf;
         diskMagic[2] = 0xb5;

src/consensus/params.h

@@ -52,6 +52,11 @@ struct Params {
     int uahfHeight;
     /** Block height at which CDHF kicks in --add by hmc*/
     int cdyHeight;
+    /** Block height at which Zawy's LWMA difficulty algorithm becomes active */
+    int CDYZawyLWMAHeight;
+    /** Limit BITCOIN_MAX_FUTURE_BLOCK_TIME **/
+    int64_t CDYMaxFutureBlockTime;
+
     /** Block height at which the new DAA becomes active */
     /** The first post-fork block of Bitcoin blockchain. **/
     uint256 BitcoinPostforkBlock;
@@ -83,14 +88,18 @@ struct Params {
     int64_t nPowTargetTimespanLegacy;
     int64_t DifficultyAdjustmentInterval() const { return nPowTargetTimespanLegacy / nPowTargetSpacing; }
     //Zcash logic for diff adjustment
-    int64_t nPowAveragingWindow;
-    int64_t nPowMaxAdjustDown;
-    int64_t nPowMaxAdjustUp;
-    int64_t AveragingWindowTimespan() const { return nPowAveragingWindow * nPowTargetSpacingCDY; }
-    int64_t MinActualTimespan() const { return (AveragingWindowTimespan() * (100 - nPowMaxAdjustUp  )) / 100; }
-    int64_t MaxActualTimespan() const { return (AveragingWindowTimespan() * (100 + nPowMaxAdjustDown)) / 100; }
+    int64_t nDigishieldAveragingWindow;
+    int64_t nDigishieldMaxAdjustDown;
+    int64_t nDigishieldMaxAdjustUp;
+    int64_t DigishieldAveragingWindowTimespan() const { return nDigishieldAveragingWindow * nPowTargetSpacingCDY; }
+    int64_t DigishieldMinActualTimespan() const { return (DigishieldAveragingWindowTimespan() * (100 - nDigishieldMaxAdjustUp  )) / 100; }
+    int64_t DigishieldMaxActualTimespan() const { return (DigishieldAveragingWindowTimespan() * (100 + nDigishieldMaxAdjustDown)) / 100; }
     uint256 nMinimumChainWork;
     uint256 defaultAssumeValid;
+
+  // Params for Zawy's LWMA difficulty adjustment algorithm. (Used by testnet and regtest)
+    int64_t nZawyLwmaAveragingWindow;  // N
+    int64_t nZawyLwmaAjustedWeight;  // k = (N+1)/2 * 0.9989^(500/N) * T   
 };
 } // namespace Consensus