Clone.sol

// SPDX-License-Identifier: BSD
pragma solidity ^0.8.4;

/// @title Clone
/// @author zefram.eth, Saw-mon & Natalie
/// @notice Provides helper functions for reading immutable args from calldata
contract Clone {

    uint256 private constant ONE_WORD = 0x20;

    /// @notice Reads an immutable arg with type address
    /// @param argOffset The offset of the arg in the packed data
    /// @return arg The arg value
    function _getArgAddress(uint256 argOffset)
        internal
        pure
        returns (address arg)
    {
        uint256 offset = _getImmutableArgsOffset();
        // solhint-disable-next-line no-inline-assembly
        assembly {
            arg := shr(0x60, calldataload(add(offset, argOffset)))
        }
    }

    /// @notice Reads an immutable arg with type uint256
    /// @param argOffset The offset of the arg in the packed data
    /// @return arg The arg value
    function _getArgUint256(uint256 argOffset)
        internal
        pure
        returns (uint256 arg)
    {
        uint256 offset = _getImmutableArgsOffset();
        // solhint-disable-next-line no-inline-assembly
        assembly {
            arg := calldataload(add(offset, argOffset))
        }
    }

    /// @notice Reads a uint256 array stored in the immutable args.
    /// @param argOffset The offset of the arg in the packed data
    /// @param arrLen Number of elements in the array
    /// @return arr The array
    function _getArgUint256Array(uint256 argOffset, uint64 arrLen)
        internal
        pure
      returns (uint256[] memory arr)
    {
        uint256 offset = _getImmutableArgsOffset() + argOffset;
        arr = new uint256[](arrLen);

        // solhint-disable-next-line no-inline-assembly
        assembly {
            calldatacopy(
                add(arr, ONE_WORD),
                offset,
                shl(5, arrLen)
            )
        }
    }

    /// @notice Reads an immutable arg with type uint64
    /// @param argOffset The offset of the arg in the packed data
    /// @return arg The arg value
    function _getArgUint64(uint256 argOffset)
        internal
        pure
        returns (uint64 arg)
    {
        uint256 offset = _getImmutableArgsOffset();
        // solhint-disable-next-line no-inline-assembly
        assembly {
            arg := shr(0xc0, calldataload(add(offset, argOffset)))
        }
    }

    /// @notice Reads an immutable arg with type uint8
    /// @param argOffset The offset of the arg in the packed data
    /// @return arg The arg value
    function _getArgUint8(uint256 argOffset) internal pure returns (uint8 arg) {
        uint256 offset = _getImmutableArgsOffset();
        // solhint-disable-next-line no-inline-assembly
        assembly {
            arg := shr(0xf8, calldataload(add(offset, argOffset)))
        }
    }

    /// @return offset The offset of the packed immutable args in calldata
    function _getImmutableArgsOffset() internal pure returns (uint256 offset) {
        // solhint-disable-next-line no-inline-assembly
        assembly {
            offset := sub(
                calldatasize(),
                shr(0xf0, calldataload(sub(calldatasize(), 2)))
            )
        }
    }
}