67 lines
2.1 KiB
Solidity
67 lines
2.1 KiB
Solidity
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// Brought from https://github.com/aragon/aragonOS/blob/v4.3.0/contracts/lib/math/SafeMath64.sol
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// Adapted to use pragma ^0.5.8 and satisfy our linter rules
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pragma solidity ^0.5.8;
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/**
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* @title SafeMath64
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* @dev Math operations for uint64 with safety checks that revert on error
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*/
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library SafeMath64 {
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string private constant ERROR_ADD_OVERFLOW = "MATH64_ADD_OVERFLOW";
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string private constant ERROR_SUB_UNDERFLOW = "MATH64_SUB_UNDERFLOW";
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string private constant ERROR_MUL_OVERFLOW = "MATH64_MUL_OVERFLOW";
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string private constant ERROR_DIV_ZERO = "MATH64_DIV_ZERO";
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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(uint64 _a, uint64 _b) internal pure returns (uint64) {
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uint256 c = uint256(_a) * uint256(_b);
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require(c < 0x010000000000000000, ERROR_MUL_OVERFLOW); // 2**64 (less gas this way)
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return uint64(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(uint64 _a, uint64 _b) internal pure returns (uint64) {
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require(_b > 0, ERROR_DIV_ZERO); // Solidity only automatically asserts when dividing by 0
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uint64 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(uint64 _a, uint64 _b) internal pure returns (uint64) {
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require(_b <= _a, ERROR_SUB_UNDERFLOW);
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uint64 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(uint64 _a, uint64 _b) internal pure returns (uint64) {
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uint64 c = _a + _b;
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require(c >= _a, ERROR_ADD_OVERFLOW);
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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(uint64 a, uint64 b) internal pure returns (uint64) {
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require(b != 0, ERROR_DIV_ZERO);
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return a % b;
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}
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}
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