Merge pull request #106 from primitivefinance/fix/dynamic-library-rou…

…nding Fix/dynamic library rounding
primitivefinance · Apr 2, 2024 · bf3c7bf · bf3c7bf
2 parents f597df3 + 4fd811a
commit bf3c7bf
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Showing 2 changed files with 13 additions and 2 deletions.
diff --git a/src/lib/DynamicParamLib.sol b/src/lib/DynamicParamLib.sol
@@ -53,6 +53,15 @@ library DynamicParamLib {
         uint256 timeDelta = updateEnd - block.timestamp;
         int256 delta = int256(target) - int256(param.lastComputedValue);
         int256 deltaPerSecond = delta / int256(timeDelta);
+
+        int256 remainder = delta % int256(timeDelta);
+
+        if (remainder > 0) {
+            param.lastComputedValue += uint256(remainder);
+        } else {
+            param.lastComputedValue -= uint256(-remainder);
+        }
+
         param.updateEnd = updateEnd;
         param.updatePerSecond = deltaPerSecond;
     }

diff --git a/test/lib/DynamicParamLib.t.sol b/test/lib/DynamicParamLib.t.sol
@@ -100,7 +100,8 @@ contract DynamicParamLibTest is Test {
     function test_DynamicParamLib_set_SetsValueIncrease() public {
         initStoredParam(10, 0, 0, 0);
         storedParam.set(20, 10);
-        assertEq(storedParam.lastComputedValue, 10);
+        // immediately updates `lastComputedValue` to 11
+        assertEq(storedParam.lastComputedValue, 11);
         assertEq(storedParam.updateEnd, 10);
         assertEq(storedParam.lastUpdateAt, block.timestamp);
         assertEq(storedParam.updatePerSecond, 1);
@@ -109,7 +110,8 @@ contract DynamicParamLibTest is Test {
     function test_DynamicParamLib_set_SetsValueDecrease() public {
         initStoredParam(20, 0, 0, 0);
         storedParam.set(10, 10);
-        assertEq(storedParam.lastComputedValue, 20);
+        // immediately updates `lastComputedValue` to 19
+        assertEq(storedParam.lastComputedValue, 19);
         assertEq(storedParam.updateEnd, 10);
         assertEq(storedParam.lastUpdateAt, block.timestamp);
         assertEq(storedParam.updatePerSecond, -1);