Fix interest per block float calculation

Signed-off-by: Anthony Fieroni <[email protected]>
DeFiCh · Jan 31, 2022 · ed5daaa · ed5daaa
1 parent 40b8d7c
commit ed5daaa
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Showing 2 changed files with 23 additions and 15 deletions.
diff --git a/src/masternodes/loan.cpp b/src/masternodes/loan.cpp
@@ -222,17 +222,6 @@ inline base_uint<128> InterestPerBlockCalculationV2(CAmount amount, CAmount toke
     return arith_uint256(amount) * netInterest * COIN / blocksPerYear;
 }
 
-static base_uint<128> InterestPerBlockCalculation(CAmount amount, CAmount tokenInterest, CAmount schemeInterest, uint32_t height)
-{
-    if (int(height) >= Params().GetConsensus().FortCanningHillHeight)
-        return InterestPerBlockCalculationV2(amount, tokenInterest, schemeInterest);
-
-    if (int(height) >= Params().GetConsensus().FortCanningMuseumHeight)
-        return std::ceil(InterestPerBlockCalculationV1<float>(amount, tokenInterest, schemeInterest));
-
-    return InterestPerBlockCalculationV1<CAmount>(amount, tokenInterest, schemeInterest);
-}
-
 CAmount CeilInterest(const base_uint<128>& value, uint32_t height)
 {
     if (int(height) >= Params().GetConsensus().FortCanningHillHeight) {
@@ -303,9 +292,15 @@ Res CLoanView::StoreInterest(uint32_t height, const CVaultId& vaultId, const std
     if (int(height) >= Params().GetConsensus().FortCanningHillHeight) {
         CBalances amounts;
         ReadBy<LoanTokenAmount>(vaultId, amounts);
-        rate.interestPerBlock = InterestPerBlockCalculation(amounts.balances[id], token->interest, scheme->rate, height);
+        rate.interestPerBlock = InterestPerBlockCalculationV2(amounts.balances[id], token->interest, scheme->rate);
+
+    } else if (int(height) >= Params().GetConsensus().FortCanningMuseumHeight) {
+        CAmount interestPerBlock = rate.interestPerBlock.GetLow64();
+        interestPerBlock += std::ceil(InterestPerBlockCalculationV1<float>(loanIncreased, token->interest, scheme->rate));
+        rate.interestPerBlock = interestPerBlock;
+
     } else
-        rate.interestPerBlock += InterestPerBlockCalculation(loanIncreased, token->interest, scheme->rate, height);
+        rate.interestPerBlock += InterestPerBlockCalculationV1<CAmount>(loanIncreased, token->interest, scheme->rate);
 
     rate.height = height;
 
@@ -345,9 +340,15 @@ Res CLoanView::EraseInterest(uint32_t height, const CVaultId& vaultId, const std
     if (int(height) >= Params().GetConsensus().FortCanningHillHeight) {
         CBalances amounts;
         ReadBy<LoanTokenAmount>(vaultId, amounts);
-        rate.interestPerBlock = InterestPerBlockCalculation(amounts.balances[id], token->interest, scheme->rate, height);
+        rate.interestPerBlock = InterestPerBlockCalculationV2(amounts.balances[id], token->interest, scheme->rate);
+
+    } else if (int(height) >= Params().GetConsensus().FortCanningMuseumHeight) {
+        CAmount interestPerBlock = rate.interestPerBlock.GetLow64();
+        CAmount newInterestPerBlock = std::ceil(InterestPerBlockCalculationV1<float>(loanDecreased, token->interest, scheme->rate));
+        rate.interestPerBlock = std::max(CAmount{0}, interestPerBlock - newInterestPerBlock);
+
     } else {
-        auto interestPerBlock = InterestPerBlockCalculation(loanDecreased, token->interest, scheme->rate, height);
+        auto interestPerBlock = InterestPerBlockCalculationV1<CAmount>(loanDecreased, token->interest, scheme->rate);
         rate.interestPerBlock = rate.interestPerBlock < interestPerBlock ? 0
                               : rate.interestPerBlock - interestPerBlock;
     }

diff --git a/src/test/amount_tests.cpp b/src/test/amount_tests.cpp
@@ -147,4 +147,11 @@ BOOST_AUTO_TEST_CASE(CTokenAmount_Sub_Negative_Result_Test)
     BOOST_CHECK_EQUAL(amount.Sub(val).msg, "amount 0.00000010 is less than 0.00000011");
 }
 
+BOOST_AUTO_TEST_CASE(CAmount_Float_Test)
+{
+    CAmount amount1 = 16765189, amount2 = 237824;
+    // https://en.wikipedia.org/wiki/Floating-point_arithmetic
+    BOOST_CHECK_EQUAL(CAmount(amount1 + float(amount2)), amount1 + amount2 - 1);
+}
+
 BOOST_AUTO_TEST_SUITE_END()