50 lines
1.0 KiB
Solidity
50 lines
1.0 KiB
Solidity
pragma solidity 0.4.18;
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/// @title SafeMath
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/// @dev Math operations with safety checks that throw on error
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library SafeMath {
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/// @dev Multiplies a times b
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function mul(uint256 a, uint256 b)
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internal
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constant
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returns (uint256)
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{
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uint256 c = a * b;
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assert(a == 0 || c / a == b);
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return c;
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}
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/// @dev Divides a by b
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function div(uint256 a, uint256 b)
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internal
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constant
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returns (uint256)
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{
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// assert(b > 0); // Solidity automatically throws when dividing by 0
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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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/// @dev Subtracts a from b
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function sub(uint256 a, uint256 b)
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internal
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constant
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returns (uint256)
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{
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assert(b <= a);
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return a - b;
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}
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/// @dev Adds a to b
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function add(uint256 a, uint256 b)
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internal
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constant
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returns (uint256)
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{
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uint256 c = a + b;
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assert(c >= a);
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return c;
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}
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}
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