FOR loop reformatting.

[novacoin.git] / src / kernel.cpp

diff --git a/src/kernel.cpp b/src/kernel.cpp
index 4055314..a3ec598 100644 (file)
--- a/src/kernel.cpp
+++ b/src/kernel.cpp
@@ -469,7 +469,7 @@ bool ScanForStakeKernelHash(MetaMap &mapMeta, uint32_t nBits, uint32_t nTime, ui
         bnTargetPerCoinDay.SetCompact(nBits);
         int64_t nValueIn = pcoin.first->vout[pcoin.second].nValue;
 
-        // Search backward in time from the given timestamp 
+        // Search backward in time from the given timestamp
         // Search nSearchInterval seconds back up to nMaxStakeSearchInterval
         // Stopping search in case of shutting down or cache invalidation
         for (unsigned int n=0; n<nCurrentSearchInterval && fCoinsDataActual && !fShutdown; n++)
@@ -512,13 +512,10 @@ bool ScanForStakeKernelHash(MetaMap &mapMeta, uint32_t nBits, uint32_t nTime, ui
 // Scan given input for kernel solution
 bool ScanInputForStakeKernelHash(CTransaction &tx, uint32_t nOut, uint32_t nBits, uint32_t nSearchInterval, std::pair<uint256, uint32_t> &solution)
 {
+    CTxDB txdb("r");
+
     CBlock block;
     CTxIndex txindex;
-    uint256 hashProofOfStake;
-
-    int nTime = GetTime();
-
-    CTxDB txdb("r");
 
     // Load transaction index item
     if (!txdb.ReadTxIndex(tx.GetHash(), txindex))
@@ -532,29 +529,58 @@ bool ScanInputForStakeKernelHash(CTransaction &tx, uint32_t nOut, uint32_t nBits
     if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
         return false;
 
+    uint32_t nTime = GetTime();
+    // Only count coins meeting min age requirement
+    if (nStakeMinAge + block.nTime > nTime)
+        nTime += (nStakeMinAge + block.nTime - nTime);
+
     // Transaction offset inside block
     uint32_t nTxOffset = txindex.pos.nTxPos - txindex.pos.nBlockPos;
+    int64_t nValueIn = tx.vout[nOut].nValue;
 
-    uint32_t nBlockTime = block.nTime;
     CBigNum bnTargetPerCoinDay;
     bnTargetPerCoinDay.SetCompact(nBits);
-    int64_t nValueIn = tx.vout[nOut].nValue;
+
+    // Get maximum possible target to filter out the majority of obviously insufficient hashes
+    CBigNum bnMaxTargetPerCoinDay = bnTargetPerCoinDay * CBigNum(nValueIn) * nStakeMaxAge / COIN / (24 * 60 * 60);
+    uint256 maxTarget = bnMaxTargetPerCoinDay.getuint256();
+
+
+    // Build static part of kernel
+    CDataStream ssKernel(SER_GETHASH, 0);
+    ssKernel << nStakeModifier;
+    ssKernel << block.nTime << nTxOffset << tx.nTime << nOut;
+    CDataStream::const_iterator it = ssKernel.begin();
+
+    // Init sha256 context and update it 
+    //   with first 16 bytes of kernel
+    SHA256_CTX ctxCurrent;
+    SHA256_Init(&ctxCurrent);
+    SHA256_Update(&ctxCurrent, (unsigned char*)&it[0], 8 + 16);
+    SHA256_CTX ctxCopy = ctxCurrent;
 
     // Search forward in time from the given timestamp
     // Stopping search in case of shutting down
-    for (unsigned int n=0; n<nSearchInterval && !fShutdown; n++)
+    for (uint32_t nTimeTx=nTime; nTimeTx<nTime+nSearchInterval && !fShutdown; nTimeTx++)
     {
-        uint32_t nTimeTx = nTime + n;
-        CBigNum bnCoinDayWeight = CBigNum(nValueIn) * GetWeight((int64_t)tx.nTime, (int64_t)nTimeTx) / COIN / (24 * 60 * 60);
-        CBigNum bnTargetProofOfStake = bnCoinDayWeight * bnTargetPerCoinDay;
+        // Complete first hashing iteration
+        uint256 hash1;
+        SHA256_Update(&ctxCurrent, (unsigned char*)&nTimeTx, 4);
+        SHA256_Final((unsigned char*)&hash1, &ctxCurrent);
 
-        // Build kernel
-        CDataStream ss(SER_GETHASH, 0);
-        ss << nStakeModifier;
-        ss << nBlockTime << nTxOffset << tx.nTime << nOut << nTimeTx;
+        // Restore old context
+        ctxCurrent = ctxCopy;
 
-        // Calculate kernel hash
-        hashProofOfStake = Hash(ss.begin(), ss.end());
+        // Finally, calculate kernel hash
+        uint256 hashProofOfStake;
+        SHA256((unsigned char*)&hash1, sizeof(hashProofOfStake), (unsigned char*)&hashProofOfStake);
+
+        // Skip if hash doesn't satisfy the maximum target
+        if (hashProofOfStake > maxTarget)
+            continue;
+
+        CBigNum bnCoinDayWeight = CBigNum(nValueIn) * GetWeight((int64_t)tx.nTime, (int64_t)nTimeTx) / COIN / (24 * 60 * 60);
+        CBigNum bnTargetProofOfStake = bnCoinDayWeight * bnTargetPerCoinDay;
 
         if (bnTargetProofOfStake >= CBigNum(hashProofOfStake))
         {