// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

library SignedMath {
    function abs(int256 x) internal pure returns (uint256) {
        if (x < 0) {
            return uint256(0 - x);
        }
        return uint256(x);
    }

    function addU(int256 x, uint256 y) internal pure returns (int256) {
        require(y <= uint256(type(int256).max), "overflow");
        return x + int256(y);
    }

    function subU(int256 x, uint256 y) internal pure returns (int256) {
        require(y <= uint256(type(int256).max), "overflow");
        return x - int256(y);
    }

    function mulU(int256 x, uint256 y) internal pure returns (int256) {
        require(y <= uint256(type(int256).max), "overflow");
        return x * int256(y);
    }

    function divU(int256 x, uint256 y) internal pure returns (int256) {
        require(y <= uint256(type(int256).max), "overflow");
        return x / int256(y);
    }
}