Restrict powLimit due to difficulty averaging

src/chainparams.cpp

@@ -28,6 +28,8 @@ using namespace std;
  * + Contains no strange transactions
  */
 
+const arith_uint256 maxUint = UintToArith256(uint256S("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"));
+
 class CMainParams : public CChainParams {
 public:
     CMainParams() {
@@ -40,8 +42,9 @@ public:
         consensus.nMajorityWindow = 4000;
         // TODO generate harder genesis block
         //consensus.powLimit = uint256S("00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
-        consensus.powLimit = uint256S("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
+        consensus.powLimit = uint256S("0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f");
         consensus.nPowAveragingWindow = 17;
+        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nPowAveragingWindow);
         consensus.nPowMaxAdjustDown = 32; // 32% adjustment down
         consensus.nPowMaxAdjustUp = 16; // 16% adjustment up
         consensus.nPowTargetSpacing = 2.5 * 60;
@@ -149,7 +152,8 @@ public:
         consensus.nMajorityEnforceBlockUpgrade = 51;
         consensus.nMajorityRejectBlockOutdated = 75;
         consensus.nMajorityWindow = 400;
-        consensus.powLimit = uint256S("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
+        consensus.powLimit = uint256S("0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f");
+        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nPowAveragingWindow);
         consensus.fPowAllowMinDifficultyBlocks = true;
         pchMessageStart[0] = 0x26;
         pchMessageStart[1] = 0xA7;
@@ -219,7 +223,8 @@ public:
         consensus.nMajorityEnforceBlockUpgrade = 750;
         consensus.nMajorityRejectBlockOutdated = 950;
         consensus.nMajorityWindow = 1000;
-        consensus.powLimit = uint256S("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
+        consensus.powLimit = uint256S("0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f");
+        assert(maxUint/UintToArith256(consensus.powLimit) >= consensus.nPowAveragingWindow);
         consensus.nPowMaxAdjustDown = 0; // Turn off adjustment down
         consensus.nPowMaxAdjustUp = 0; // Turn off adjustment up
         pchMessageStart[0] = 0xaa;