19 lines
647 B
Solidity
19 lines
647 B
Solidity
pragma solidity 0.5.12;
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library SafeMath256 {
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function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
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require((z = x + y) >= x, "ds-math-add-overflow");
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}
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function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
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require((z = x - y) <= x, "ds-math-sub-underflow");
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}
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function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
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require(y == 0 || (z = x * y) / y == x, "ds-math-mul-overflow");
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}
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function downcast128(uint256 y) internal pure returns (uint128 z) {
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require(y <= uint128(-1), "downcast-128-overflow");
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z = uint128(y);
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}
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}
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