The 'rtwtypes.h' header file generated by Embedded Coder defines the mapping between Simulink data types and primitive C/C++ data types. Embedded Coder makes such decisions based on the word length of target hardware code generation to make sure generated code leads to the same result as in simulation. This file should not be manually edited for customization.
Although you should not manually customize this file, you can still customize your typedefs. In some cases customization is needed so that generated code aligns with coding standards. In this case, use data type replacement.
Data type replacement allows you to import customized data type aliases defined in your own header files and use them to define Simulink data types in generated code. If a Simulink data type is defined with an alias, then its definition in 'rtwtypes.h' is not used. Instead, the compiler goes to the custom header file for the definition.
For more information about data type replacement, please see the following reference:
