Refactor proof of work related functions out of main

src/pow.h

@@ -0,0 +1,23 @@
+
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_POW_H
+#define BITCOIN_POW_H
+
+#include <stdint.h>
+
+class CBlockIndex;
+class CBlockHeader;
+class uint256;
+
+unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock);
+
+/** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
+bool CheckProofOfWork(uint256 hash, unsigned int nBits);
+/** Calculate the minimum amount of work a received block needs, without knowing its direct parent */
+unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime);
+
+#endif