41 lines
1.2 KiB
Solidity
41 lines
1.2 KiB
Solidity
pragma solidity ^0.5.11;
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library SafeMath {
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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, "SafeMath: addition overflow");
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return c;
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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, "SafeMath: subtraction overflow");
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uint256 c = a - b;
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return c;
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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-contracts/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, "SafeMath: multiplication overflow");
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return c;
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}
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function div(uint256 a, uint256 b) internal pure returns (uint256) {
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// Solidity only automatically asserts when dividing by 0
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require(b > 0, "SafeMath: division by zero");
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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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