Fix ctB calc

src/pow.cpp

@@ -189,10 +189,13 @@ arith_uint256 zawy_exponential(arith_uint256 bnTarget,int32_t mult)
 
 arith_uint256 zawy_ctB(arith_uint256 bnTarget,uint32_t solvetime)
 {
-    bnTarget /= arith_uint256(K);
-    bnTarget *= arith_uint256((int64_t)solvetime * solvetime * 1000);
-    bnTarget /= arith_uint256(T * T * 784);
-    bnTarget *= arith_uint256(K);
+    int64_t num;
+    num = (K * (int64_t)solvetime * solvetime * 1000) / (T * T * 784);
+    if ( num > 1 )
+    {
+        bnTarget /= arith_uint256(K);
+        bnTarget *= arith_uint256(num);
+    }
     return(bnTarget);
 }
 

src/rpc/mining.cpp

@@ -428,7 +428,7 @@ UniValue genminingCSV(const UniValue& params, bool fHelp)
                 str[32] = 0;
                 //hash = pindex->GetBlockHash();
                 memset(&hash,0,sizeof(hash));
-                if ( (pindex->nBits & 3) != 0 )
+                if ( i > 64 && (pindex->nBits & 3) != 0 )
                     hash = zawy_ctB(bnTarget,solvetime);
                 for (z=0; z<16; z++)
                     sprintf(&str2[z<<1],"%02x",((uint8_t *)&hash)[31-z]);