Skip to content
Permalink
next
Switch branches/tags
Go to file
 
 
Cannot retrieve contributors at this time
// See https://github.com/OpenZeppelin/openzeppelin-solidity/blob/d51e38758e1d985661534534d5c61e27bece5042/contracts/math/SafeMath.sol
// Adapted to use pragma ^0.4.24 and satisfy our linter rules
pragma solidity ^0.4.24;
/**
* @title SafeMath
* @dev Math operations with safety checks that revert on error
*/
library SafeMath {
string private constant ERROR_ADD_OVERFLOW = "MATH_ADD_OVERFLOW";
string private constant ERROR_SUB_UNDERFLOW = "MATH_SUB_UNDERFLOW";
string private constant ERROR_MUL_OVERFLOW = "MATH_MUL_OVERFLOW";
string private constant ERROR_DIV_ZERO = "MATH_DIV_ZERO";
/**
* @dev Multiplies two numbers, reverts on overflow.
*/
function mul(uint256 _a, uint256 _b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
if (_a == 0) {
return 0;
}
uint256 c = _a * _b;
require(c / _a == _b, ERROR_MUL_OVERFLOW);
return c;
}
/**
* @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
*/
function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
require(_b > 0, ERROR_DIV_ZERO); // Solidity only automatically asserts when dividing by 0
uint256 c = _a / _b;
// assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
require(_b <= _a, ERROR_SUB_UNDERFLOW);
uint256 c = _a - _b;
return c;
}
/**
* @dev Adds two numbers, reverts on overflow.
*/
function add(uint256 _a, uint256 _b) internal pure returns (uint256) {
uint256 c = _a + _b;
require(c >= _a, ERROR_ADD_OVERFLOW);
return c;
}
/**
* @dev Divides two numbers and returns the remainder (unsigned integer modulo),
* reverts when dividing by zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0, ERROR_DIV_ZERO);
return a % b;
}
}