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42 lines
1.5 KiB
Solidity
42 lines
1.5 KiB
Solidity
// SPDX-License-Identifier: agpl-3.0
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pragma solidity ^0.6.8;
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import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
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/**
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* @title PercentageMath library
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* @author Aave
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* @notice Provides functions to calculate percentages.
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* @dev Percentages are defined by default with 2 decimals of precision (100.00). The precision is indicated by PERCENTAGE_FACTOR
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* @dev Operations are rounded half up
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**/
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library PercentageMath {
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using SafeMath for uint256;
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uint256 constant PERCENTAGE_FACTOR = 1e4; //percentage plus two decimals
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uint256 constant HALF_PERCENT = PERCENTAGE_FACTOR / 2;
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/**
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* @dev executes a percentage multiplication
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* @param _value the value of which the percentage needs to be calculated
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* @param _percentage the percentage of the value to be calculated
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* @return the _percentage of _value
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**/
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function percentMul(uint256 _value, uint256 _percentage) internal pure returns (uint256) {
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return HALF_PERCENT.add(_value.mul(_percentage)).div(PERCENTAGE_FACTOR);
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}
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/**
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* @dev executes a percentage division
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* @param _value the value of which the percentage needs to be calculated
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* @param _percentage the percentage of the value to be calculated
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* @return the _value divided the _percentage
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**/
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function percentDiv(uint256 _value, uint256 _percentage) internal pure returns (uint256) {
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uint256 halfPercentage = _percentage / 2;
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return halfPercentage.add(_value.mul(PERCENTAGE_FACTOR)).div(_percentage);
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}
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}
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