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69 lines
1.7 KiB
69 lines
1.7 KiB
6 years ago
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// Copyright (c) 2016 Smart Contract Solutions, Inc.
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pragma solidity ^0.4.24;
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/**
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* @title SafeMath
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* @dev Math operations with safety checks that revert on error
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*/
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library SafeMath {
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/**
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* @dev Multiplies two numbers, reverts on overflow.
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*/
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function mul(uint256 _a, uint256 _b) internal pure returns (uint256) {
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// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
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// benefit is lost if 'b' is also tested.
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// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
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if (_a == 0) {
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return 0;
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}
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uint256 c = _a * _b;
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require(c / _a == _b);
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return c;
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}
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/**
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* @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
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*/
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function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
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require(_b > 0); // Solidity only automatically asserts when dividing by 0
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uint256 c = _a / _b;
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// assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold
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return c;
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}
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/**
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* @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
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*/
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function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
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require(_b <= _a);
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uint256 c = _a - _b;
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return c;
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}
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/**
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* @dev Adds two numbers, reverts on overflow.
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*/
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function add(uint256 _a, uint256 _b) internal pure returns (uint256) {
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uint256 c = _a + _b;
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require(c >= _a);
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return c;
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}
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/**
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* @dev Divides two numbers and returns the remainder (unsigned integer modulo),
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* reverts when dividing by zero.
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*/
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function mod(uint256 a, uint256 b) internal pure returns (uint256) {
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require(b != 0);
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return a % b;
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}
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}
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