If your generated code must use functions and operators that are consistent with external code, configure the code generator to use a code replacement library (CRL). By default, the code generator does not apply a code replacement library. You can choose from several libraries that MathWorks® provides, including GNU C99 extensions, AUTOSAR 4.0, and several Intel® platform-specific IPP and IPP/SSE libraries. Depending on the products that you have, other libraries might be available. If you have Embedded Coder® software, you can view and choose from additional libraries and you can create custom code replacement libraries.