NoBey/openzeppelin-contracts
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Gas optimization on average function of Math.sol (#2757)

Browse Source 
* change implementation to save gas

* add average test with two max uni256 number
This commit is contained in:
rotcivegaf
2021-07-10 21:28:12 +02:00
committed by GitHub
parent 1c1ebd765d
commit 6d97f09195
2 changed files with 7 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
contracts/utils/math/Math.sol
View File

@ -25,8 +25,8 @@ library Math {
* zero. * zero.
*/ */
function average(uint256 a, uint256 b) internal pure returns (uint256) { function average(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b) / 2 can overflow, so we distribute. // (a + b) / 2 can overflow.
return (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2); return (a & b) + (a ^ b) / 2;
} }
/** /**

5
test/utils/math/Math.test.js
View File

@ -54,6 +54,11 @@ contract('Math', function (accounts) {
const b = new BN('84346'); const b = new BN('84346');
expect(await this.math.average(a, b)).to.be.bignumber.equal(bnAverage(a, b)); expect(await this.math.average(a, b)).to.be.bignumber.equal(bnAverage(a, b));
}); });
it('is correctly calculated with two max uint256 numbers', async function () {
const a = MAX_UINT256;
expect(await this.math.average(a, a)).to.be.bignumber.equal(bnAverage(a, a));
});
}); });
describe('ceilDiv', function () { describe('ceilDiv', function () {