53 lines
1.4 KiB
Solidity
53 lines
1.4 KiB
Solidity
pragma solidity ^0.5.0;
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/**
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* @title SafeMath
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* @dev Math operations with safety checks that throw on error
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*/
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library SafeMath {
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/**
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* @dev Multiplies two numbers, throws on overflow.
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*/
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function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
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// Gas optimization: this is cheaper than asserting '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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c = a * b;
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assert(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.
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*/
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function div(uint256 a, uint256 b) internal pure returns (uint256) {
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// assert(b > 0); // Solidity automatically throws 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 a / b;
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}
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/**
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* @dev Subtracts two numbers, throws 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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assert(b <= a);
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return a - b;
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}
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/**
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* @dev Adds two numbers, throws on overflow.
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*/
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function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
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c = a + b;
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assert(c >= a);
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return c;
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}
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}
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