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Merged
merged 4 commits into from
Sep 29, 2022
Merged

Math library updates #137

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91a6bbf
optimize Math#average function
ItsNickBarry Sep 28, 2022
720f4d5
remove additional operation from Math#average function
ItsNickBarry Sep 28, 2022
7b92a45
import Math#average implementation from OZ, add additional test case
ItsNickBarry Sep 28, 2022
36d8d25
add max and min functions to Math library, use static calls in tests
ItsNickBarry Sep 29, 2022
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25 changes: 24 additions & 1 deletion contracts/utils/Math.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,37 @@
pragma solidity ^0.8.8;

library Math {
/**
* @notice select the greater of two numbers
* @param a first number
* @param b second number
* @return greater number
*/
function max(uint256 a, uint256 b) internal pure returns (uint256) {
return a > b ? a : b;
}

/**
* @notice select the lesser of two numbers
* @param a first number
* @param b second number
* @return lesser number
*/
function min(uint256 a, uint256 b) internal pure returns (uint256) {
return a > b ? b : a;
}

/**
* @notice calculate the average of two numbers, rounded down
* @dev derived from https://github.com/OpenZeppelin/openzeppelin-contracts (MIT license)
* @param a first number
* @param b second number
* @return mean value
*/
function average(uint256 a, uint256 b) internal pure returns (uint256) {
return (a >> 1) + (b >> 1) + (((a & 1) + (b & 1)) >> 1);
unchecked {
return (a & b) + ((a ^ b) >> 1);
}
}

/**
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10 changes: 9 additions & 1 deletion contracts/utils/MathMock.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,16 @@ import { Math } from './Math.sol';
contract MathMock {
using Math for uint256;

function max(uint256 a, uint256 b) external pure returns (uint256) {
return Math.max(a, b);
}

function min(uint256 a, uint256 b) external pure returns (uint256) {
return Math.min(a, b);
}

function average(uint256 a, uint256 b) external pure returns (uint256) {
return a.average(b);
return Math.average(a, b);
}

function sqrt(uint256 x) external pure returns (uint256) {
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95 changes: 83 additions & 12 deletions test/utils/Math.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11,56 +11,127 @@ describe('Math', function () {
});

describe('__internal', function () {
describe('#max(uint256,uint256)', function () {
it('returns the greater of two numbers', async () => {
expect(
await instance.callStatic.max(
ethers.constants.One,
ethers.constants.Two,
),
).to.equal(ethers.constants.Two);

expect(
await instance.callStatic.max(
ethers.constants.Two,
ethers.constants.One,
),
).to.equal(ethers.constants.Two);

expect(
await instance.callStatic.max(
ethers.constants.One,
ethers.constants.One,
),
).to.equal(ethers.constants.One);

expect(
await instance.callStatic.max(
ethers.constants.Zero,
ethers.constants.MaxUint256,
),
).to.equal(ethers.constants.MaxUint256);
});
});

describe('#min(uint256,uint256)', function () {
it('returns the lesser of two numbers', async () => {
expect(
await instance.callStatic.min(
ethers.constants.One,
ethers.constants.Two,
),
).to.equal(ethers.constants.One);

expect(
await instance.callStatic.min(
ethers.constants.Two,
ethers.constants.One,
),
).to.equal(ethers.constants.One);

expect(
await instance.callStatic.min(
ethers.constants.One,
ethers.constants.One,
),
).to.equal(ethers.constants.One);

expect(
await instance.callStatic.min(
ethers.constants.Zero,
ethers.constants.MaxUint256,
),
).to.equal(ethers.constants.Zero);
});
});

describe('#average(uint256,uint256)', function () {
it('returns the average of two positive numbers from 0 to maxUint256', async function () {
expect(
await instance.average(
await instance.callStatic.average(
ethers.BigNumber.from('11'),
ethers.BigNumber.from('5'),
),
).to.equal(ethers.BigNumber.from('8'));

expect(
await instance.average(
await instance.callStatic.average(
ethers.BigNumber.from('6'),
ethers.BigNumber.from('5'),
),
).to.equal(ethers.BigNumber.from('5'));

expect(
await instance.average(
await instance.callStatic.average(
ethers.BigNumber.from('0'),
ethers.BigNumber.from('0'),
),
).to.equal(ethers.BigNumber.from('0'));

expect(
await instance.average(
await instance.callStatic.average(
ethers.constants.MaxUint256,
ethers.constants.MaxUint256,
),
).to.equal(ethers.constants.MaxUint256);

expect(
await instance.callStatic.average(
ethers.constants.MaxUint256,
ethers.constants.MaxUint256.sub(ethers.constants.One),
),
).to.equal(ethers.constants.MaxUint256.sub(ethers.constants.One));
});
});

describe('#sqrt(uint256)', function () {
it('returns the sqrt of a positive integer from 0 to maxUint256', async function () {
expect(await instance.sqrt(ethers.BigNumber.from('16'))).to.eq(
ethers.BigNumber.from('4'),
);
expect(
await instance.callStatic.sqrt(ethers.BigNumber.from('16')),
).to.eq(ethers.BigNumber.from('4'));

for (let i = 10; i < 16; i++) {
expect(
await instance.sqrt(ethers.BigNumber.from(i.toString())),
await instance.callStatic.sqrt(ethers.BigNumber.from(i.toString())),
).to.eq(ethers.BigNumber.from('3'));
}

expect(await instance.sqrt(ethers.BigNumber.from('0'))).to.eq(
ethers.BigNumber.from('0'),
);
expect(
await instance.callStatic.sqrt(ethers.BigNumber.from('0')),
).to.eq(ethers.BigNumber.from('0'));

expect(
await instance.sqrt(
await instance.callStatic.sqrt(
ethers.constants.MaxUint256.sub(ethers.BigNumber.from('1')),
),
).to.eq(
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