nadin data for issue #123

data/nadin-G.md

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+[GAS-01] Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead
+When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.
+https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html
+01: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/utils/Version.sol#L5
+02: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/utils/Version.sol#L9
+03: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/utils/Version.sol#L13
+04: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/VRFNFTRandomDraw.sol#L22
+05: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/VRFNFTRandomDraw.sol#L24
+06: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/VRFNFTRandomDraw.sol#L26
+
+[GAS-02] ADD UNCHECKED {} FOR SUBTRACTIONS WHERE THE OPERANDS CANNOT UNDERFLOW BECAUSE OF A PREVIOUS REQUIRE() OR IF-STATEMENT
+EX: require(a <= b); x = b - a => require(a <= b); unchecked { x = b - a }
+01: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/VRFNFTRandomDraw.sol#L114
+
+[GAS-03] Functions guaranteed to revert when called by normal users can be marked payable
+If a function modifier such as onlyOwner is used, the function will revert if a normal user tries to pay the function. Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided. The extra opcodes avoided are
+CALLVALUE(2),DUP1(3),ISZERO(3),PUSH2(3),JUMPI(10),PUSH1(3),DUP1(3),REVERT(0),JUMPDEST(1),POP(2), which costs an average of about 21 gas per call to the function, in addition to the extra deployment cost
+01: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/VRFNFTRandomDraw.sol#L203
+02: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/VRFNFTRandomDraw.sol#L304
+03: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/ownable/OwnableUpgradeable.sol#L102-L105
+04: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/ownable/OwnableUpgradeable.sol#L114
+05: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/ownable/OwnableUpgradeable.sol#L119
+06: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/ownable/OwnableUpgradeable.sol#L128
+
+[GAS-04]  Struct packing
+We can use the uint types uint8, uint16, uint32, etc, though Solidity reserves 256 bits of storage regardless of the uint type meaning, in normal instances, there's no cost saving. However, if you have multiple uints inside a struct, using a smaller-sized uint when possible will allow Solidity to pack these variables together to take up less storage. 
+01: https://github.com/code-423n4/2022-12-forgeries/blob/fc271cf20c05ce857d967728edfb368c58881d85/src/interfaces/IVRFNFTRandomDraw.sol#L71-L90
+