X-Git-Url: https://git.novaco.in/?a=blobdiff_plain;f=src%2Fkernel.cpp;h=58a4b88538bf9ae0b965e96ae59bf27219ffd26c;hb=56d7e2c8baefaa0229b42cef66c97da22c42dd61;hp=4055314749a6bf60d9d75ab872a31c7d688d2241;hpb=1e7993f68d8ada2bf6a523ac3b4afec64157f8ed;p=novacoin.git

diff --git a/src/kernel.cpp b/src/kernel.cpp
index 4055314..58a4b88 100644
--- 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++)
@@ -509,52 +509,55 @@ bool ScanForStakeKernelHash(MetaMap &mapMeta, uint32_t nBits, uint32_t nTime, ui
     return false;
 }
 
-// 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)
+// Precompute hashing state for static part of kernel
+void GetKernelMidstate(uint64_t nStakeModifier, uint32_t nBlockTime, uint32_t nTxOffset, uint32_t nInputTxTime, uint32_t nOut, SHA256_CTX &ctx)
 {
-    CBlock block;
-    CTxIndex txindex;
-    uint256 hashProofOfStake;
-
-    int nTime = GetTime();
-
-    CTxDB txdb("r");
-
-    // Load transaction index item
-    if (!txdb.ReadTxIndex(tx.GetHash(), txindex))
-        return false;
-
-    // Read block header
-    if (!block.ReadFromDisk(txindex.pos.nFile, txindex.pos.nBlockPos, false))
-        return false;
-
-    uint64_t nStakeModifier = 0;
-    if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
-        return false;
-
-    // Transaction offset inside block
-    uint32_t nTxOffset = txindex.pos.nTxPos - txindex.pos.nBlockPos;
+    // Build static part of kernel
+    CDataStream ssKernel(SER_GETHASH, 0);
+    ssKernel << nStakeModifier;
+    ssKernel << nBlockTime << nTxOffset << nInputTxTime << nOut;
+    CDataStream::const_iterator it = ssKernel.begin();
+
+    // Init sha256 context and update it 
+    //   with first 24 bytes of kernel
+    SHA256_Init(&ctx);
+    SHA256_Update(&ctx, (unsigned char*)&it[0], 8 + 16);
+}
 
-    uint32_t nBlockTime = block.nTime;
+// Scan given midstate for solution
+bool ScanMidstateForward(SHA256_CTX &ctx, uint32_t nBits, uint32_t nInputTxTime, int64_t nValueIn, std::pair<uint32_t, uint32_t> &SearchInterval, std::pair<uint256, uint32_t> &solution)
+{
     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();
+
+    SHA256_CTX ctxCopy = ctx;
 
     // 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=SearchInterval.first; nTimeTx<SearchInterval.second && !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(&ctxCopy, (unsigned char*)&nTimeTx, 4);
+        SHA256_Final((unsigned char*)&hash1, &ctxCopy);
 
-        // Build kernel
-        CDataStream ss(SER_GETHASH, 0);
-        ss << nStakeModifier;
-        ss << nBlockTime << nTxOffset << tx.nTime << nOut << nTimeTx;
+        // Restore context
+        ctxCopy = ctx;
+
+        // Finally, calculate kernel hash
+        uint256 hashProofOfStake;
+        SHA256((unsigned char*)&hash1, sizeof(hashProofOfStake), (unsigned char*)&hashProofOfStake);
 
-        // Calculate kernel hash
-        hashProofOfStake = Hash(ss.begin(), ss.end());
+        // Skip if hash doesn't satisfy the maximum target
+        if (hashProofOfStake > maxTarget)
+            continue;
+
+        CBigNum bnCoinDayWeight = CBigNum(nValueIn) * GetWeight((int64_t)nInputTxTime, (int64_t)nTimeTx) / COIN / (24 * 60 * 60);
+        CBigNum bnTargetProofOfStake = bnCoinDayWeight * bnTargetPerCoinDay;
 
         if (bnTargetProofOfStake >= CBigNum(hashProofOfStake))
         {
@@ -614,7 +617,7 @@ uint32_t GetStakeModifierChecksum(const CBlockIndex* pindex)
     ss << pindex->nFlags << pindex->hashProofOfStake << pindex->nStakeModifier;
     uint256 hashChecksum = Hash(ss.begin(), ss.end());
     hashChecksum >>= (256 - 32);
-    return hashChecksum.Get64();
+    return static_cast<uint32_t>(hashChecksum.Get64());
 }
 
 // Check stake modifier hard checkpoints