Move CBlockIndex::GetBlockWork() to pow::GetProofIncrement(nBits)

1 files changed, 15 insertions, 0 deletions

diff --git a/src/pow.cpp b/src/pow.cpp
index a99c582d7..d76928bda 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -127,3 +127,18 @@ void UpdateTime(CBlockHeader* pblock, const CBlockIndex* pindexPrev)
     if (Params().AllowMinDifficultyBlocks())
         pblock->nBits = GetNextWorkRequired(pindexPrev, pblock);
 }
+
+uint256 GetProofIncrement(unsigned int nBits)
+{
+    uint256 bnTarget;
+    bool fNegative;
+    bool fOverflow;
+    bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
+    if (fNegative || fOverflow || bnTarget == 0)
+        return 0;
+    // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256
+    // as it's too large for a uint256. However, as 2**256 is at least as large
+    // as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / (bnTarget+1)) + 1,
+    // or ~bnTarget / (nTarget+1) + 1.
+    return (~bnTarget / (bnTarget + 1)) + 1;
+}