{
    "Function": "_decodeLength",
    "File": "packages/protocol/contracts/thirdparty/optimism/rlp/RLPReader.sol",
    "Parent Contracts": [],
    "High-Level Calls": [],
    "Internal Calls": [
        "require(bool,string)",
        "mload(uint256)",
        "require(bool,string)",
        "require(bool,string)",
        "require(bool,string)",
        "mload(uint256)",
        "mload(uint256)",
        "require(bool,string)",
        "require(bool,string)",
        "require(bool,string)",
        "mload(uint256)",
        "require(bool,string)",
        "mload(uint256)",
        "require(bool,string)",
        "mload(uint256)",
        "require(bool,string)",
        "require(bool,string)",
        "byte(uint256,uint256)",
        "require(bool,string)"
    ],
    "Library Calls": [],
    "Low-Level Calls": [],
    "Code": "function _decodeLength(RLPItem memory _in)\n        private\n        pure\n        returns (uint256 offset_, uint256 length_, RLPItemType type_)\n    {\n        // Short-circuit if there's nothing to decode, note that we perform this check when\n        // the user creates an RLP item via toRLPItem, but it's always possible for them to bypass\n        // that function and create an RLP item directly. So we need to check this anyway.\n        require(\n            _in.length > 0,\n            \"RLPReader: length of an RLP item must be greater than zero to be decodable\"\n        );\n\n        MemoryPointer ptr = _in.ptr;\n        uint256 prefix;\n        assembly {\n            prefix := byte(0, mload(ptr))\n        }\n\n        if (prefix <= 0x7f) {\n            // Single byte.\n            return (0, 1, RLPItemType.DATA_ITEM);\n        } else if (prefix <= 0xb7) {\n            // Short string.\n\n            // slither-disable-next-line variable-scope\n            uint256 strLen = prefix - 0x80;\n\n            require(\n                _in.length > strLen,\n                \"RLPReader: length of content must be greater than string length (short string)\"\n            );\n\n            bytes1 firstByteOfContent;\n            assembly {\n                firstByteOfContent := and(mload(add(ptr, 1)), shl(248, 0xff))\n            }\n\n            require(\n                strLen != 1 || firstByteOfContent >= 0x80,\n                \"RLPReader: invalid prefix, single byte < 0x80 are not prefixed (short string)\"\n            );\n\n            return (1, strLen, RLPItemType.DATA_ITEM);\n        } else if (prefix <= 0xbf) {\n            // Long string.\n            uint256 lenOfStrLen = prefix - 0xb7;\n\n            require(\n                _in.length > lenOfStrLen,\n                \"RLPReader: length of content must be > than length of string length (long string)\"\n            );\n\n            bytes1 firstByteOfContent;\n            assembly {\n                firstByteOfContent := and(mload(add(ptr, 1)), shl(248, 0xff))\n            }\n\n            require(\n                firstByteOfContent != 0x00,\n                \"RLPReader: length of content must not have any leading zeros (long string)\"\n            );\n\n            uint256 strLen;\n            assembly {\n                strLen := shr(sub(256, mul(8, lenOfStrLen)), mload(add(ptr, 1)))\n            }\n\n            require(\n                strLen > 55,\n                \"RLPReader: length of content must be greater than 55 bytes (long string)\"\n            );\n\n            require(\n                _in.length > lenOfStrLen + strLen,\n                \"RLPReader: length of content must be greater than total length (long string)\"\n            );\n\n            return (1 + lenOfStrLen, strLen, RLPItemType.DATA_ITEM);\n        } else if (prefix <= 0xf7) {\n            // Short list.\n            // slither-disable-next-line variable-scope\n            uint256 listLen = prefix - 0xc0;\n\n            require(\n                _in.length > listLen,\n                \"RLPReader: length of content must be greater than list length (short list)\"\n            );\n\n            return (1, listLen, RLPItemType.LIST_ITEM);\n        } else {\n            // Long list.\n            uint256 lenOfListLen = prefix - 0xf7;\n\n            require(\n                _in.length > lenOfListLen,\n                \"RLPReader: length of content must be > than length of list length (long list)\"\n            );\n\n            bytes1 firstByteOfContent;\n            assembly {\n                firstByteOfContent := and(mload(add(ptr, 1)), shl(248, 0xff))\n            }\n\n            require(\n                firstByteOfContent != 0x00,\n                \"RLPReader: length of content must not have any leading zeros (long list)\"\n            );\n\n            uint256 listLen;\n            assembly {\n                listLen := shr(sub(256, mul(8, lenOfListLen)), mload(add(ptr, 1)))\n            }\n\n            require(\n                listLen > 55,\n                \"RLPReader: length of content must be greater than 55 bytes (long list)\"\n            );\n\n            require(\n                _in.length > lenOfListLen + listLen,\n                \"RLPReader: length of content must be greater than total length (long list)\"\n            );\n\n            return (1 + lenOfListLen, listLen, RLPItemType.LIST_ITEM);\n        }\n    }"
}