```\nFile: SDLPoolCCIPControllerPrimary.sol\n    function _ccipReceive(Client.Any2EVMMessage memory _message) internal override {\n        uint64 sourceChainSelector = _message.sourceChainSelector;\n\n        (uint256 numNewRESDLTokens, int256 totalRESDLSupplyChange) = abi.decode(_message.data, (uint256, int256));\n\n        if (totalRESDLSupplyChange > 0) {\n            reSDLSupplyByChain[sourceChainSelector] += uint256(totalRESDLSupplyChange);\n        } else if (totalRESDLSupplyChange < 0) {\n            reSDLSupplyByChain[sourceChainSelector] -= uint256(-1 * totalRESDLSupplyChange);\n        }\n\n        uint256 mintStartIndex = ISDLPoolPrimary(sdlPool).handleIncomingUpdate(numNewRESDLTokens, totalRESDLSupplyChange);\n\n        _ccipSendUpdate(sourceChainSelector, mintStartIndex);\n\n        emit MessageReceived(_message.messageId, sourceChainSelector);\n    }\n```\n