update(TwabLib): uniform uint types for calculations

contracts/libraries/ExtendedSafeCastLib.sol

@@ -32,4 +32,19 @@ library ExtendedSafeCastLib {
         require(value <= type(uint208).max, "SafeCast: value doesn't fit in 208 bits");
         return uint208(value);
     }
+
+    /**
+     * @dev Returns the downcasted uint224 from uint256, reverting on
+     * overflow (when the input is greater than largest uint224).
+     *
+     * Counterpart to Solidity's `uint224` operator.
+     *
+     * Requirements:
+     *
+     * - input must fit into 224 bits
+     */
+    function toUint224(uint256 value) internal pure returns (uint224) {
+        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
+        return uint224(value);
+    }
 }

contracts/libraries/TwabLib.sol

@@ -134,7 +134,9 @@ library TwabLib {
         ObservationLib.Observation[MAX_CARDINALITY] storage _twabs,
         AccountDetails memory _accountDetails
     ) internal view returns (uint24 index, ObservationLib.Observation memory twab) {
-        index = uint24(RingBufferLib.mostRecentIndex(_accountDetails.nextTwabIndex, MAX_CARDINALITY));
+        index = uint24(
+            RingBufferLib.mostRecentIndex(_accountDetails.nextTwabIndex, MAX_CARDINALITY)
+        );
         twab = _twabs[index];
     }
 
@@ -311,15 +313,15 @@ library TwabLib {
     /// @return New TWAB that was recorded.
     function _computeNextTwab(
         ObservationLib.Observation memory _currentTwab,
-        uint256 _currentBalance,
+        uint224 _currentBalance,
         uint32 _time
     ) private pure returns (ObservationLib.Observation memory) {
         // New twab amount = last twab amount (or zero) + (current amount * elapsed seconds)
         return
             ObservationLib.Observation({
-                amount: (uint256(_currentTwab.amount) +
-                    (_currentBalance * (_time.checkedSub(_currentTwab.timestamp, _time))))
-                    .toUint208(),
+                amount: _currentTwab.amount +
+                        _currentBalance *
+                        (_time.checkedSub(_currentTwab.timestamp, _time)),
                 timestamp: _time
             });
     }

test/DrawCalculator.test.ts

@@ -337,7 +337,7 @@ describe('DrawCalculator', () => {
             const userRandomNumber =
                 '0x369ddb959b07c1d22a9bada1f3420961d0e0252f73c0f5b2173d7f7c6fe12b70'; // intentionally same as winning random number
 
-                const prizeDistributionIndex: BigNumber =
+            const prizeDistributionIndex: BigNumber =
                 await drawCalculator.calculateDistributionIndex(
                     userRandomNumber,
                     winningRandomNumber,

test/libraries/OverflowSafeComparator.test.ts

@@ -70,7 +70,11 @@ describe('overflowSafeComparatorLib', () => {
             const timestampB = currentTimestamp - 100;
 
             expect(
-                await overflowSafeComparatorLib.lteHarness(timestampA, timestampB, currentTimestamp),
+                await overflowSafeComparatorLib.lteHarness(
+                    timestampA,
+                    timestampB,
+                    currentTimestamp,
+                ),
             ).to.equal(true);
         });
 
@@ -79,7 +83,11 @@ describe('overflowSafeComparatorLib', () => {
             const timestampB = timestampA;
 
             expect(
-                await overflowSafeComparatorLib.lteHarness(timestampA, timestampB, currentTimestamp),
+                await overflowSafeComparatorLib.lteHarness(
+                    timestampA,
+                    timestampB,
+                    currentTimestamp,
+                ),
             ).to.equal(true);
         });
 
@@ -88,7 +96,11 @@ describe('overflowSafeComparatorLib', () => {
             const timestampB = currentTimestamp + 1000;
 
             expect(
-                await overflowSafeComparatorLib.lteHarness(timestampA, timestampB, currentTimestamp),
+                await overflowSafeComparatorLib.lteHarness(
+                    timestampA,
+                    timestampB,
+                    currentTimestamp,
+                ),
             ).to.equal(false);
         });
 
@@ -97,7 +109,11 @@ describe('overflowSafeComparatorLib', () => {
             const timestampB = currentTimestamp - 1000;
 
             expect(
-                await overflowSafeComparatorLib.lteHarness(timestampA, timestampB, currentTimestamp),
+                await overflowSafeComparatorLib.lteHarness(
+                    timestampA,
+                    timestampB,
+                    currentTimestamp,
+                ),
             ).to.equal(true);
         });
 
@@ -106,7 +122,11 @@ describe('overflowSafeComparatorLib', () => {
             const timestampB = timestampA;
 
             expect(
-                await overflowSafeComparatorLib.lteHarness(timestampA, timestampB, currentTimestamp),
+                await overflowSafeComparatorLib.lteHarness(
+                    timestampA,
+                    timestampB,
+                    currentTimestamp,
+                ),
             ).to.equal(true);
         });
     });