Avoid reuse of local variables in Embedded coder

I'm generating code for an m-function in the simulink enviroment which solves an MPC algorithm. When the C-code is generated, some variables are used multiple times in the generated code, in different contexts. This behaviour breaks down my algorithm, and the resulting C-code does not produce the desired output (in this particular case, it does not produce an output at all). I have seen that using 'config.PreserveVariableNames = "UserNames"' produce code which does not modify the local variables. However, the configuration has to be applied using the codegen command. I have tried to pass this configuration to simulink without luck. Is there a way to tell the Embedded Coder to not modify the local variables in the m-function when generating code from Simulink?

Answer 1

[Fangjun Jiang]

That is probably not the correct option. You should try to disable the "Reuse local block outputs" option.

https://www.mathworks.com/help/rtw/ref/optimization-pane-general.html

There is a "PreserveName" option in Simulink Coder but it is reserved by the Mathworks. https://www.mathworks.com/help/rtw/ref/code-generation-pane-general.html

[Felipe Herrera]

Thank you for your answer. Sadly, It didn't work. The embedded coder is still not capable of translating accurately the MATLAB code written in an m-function in simulink to C code.

[Fangjun Jiang]

Okay. It seems that even though you are generating code in Simulink, the MATLAB Function block uses MATLAB Coder to generate code. This quote is from doc "The MATLAB Function block uses the same infrastructure as MATLAB Coder, which you use to generate C/C++ code from MATLAB code outside of Simulink."

So you could open the MATLAB Coder App alone and try to generate code for your function first. Along the way, there is a setting you can choose for "Preserve Variable Names". Compare this code with the code generated from Simulink.

Then, when you generate code in Simulink using Embedded Coder, you can follow this page. There is an option for "PreserveVariableNames".

"Preserve variable names" and "Do not re-use variable names" are two different things, but if the original M-code doesn't re-use variable names, then I assume the generated C code won't re-use variable names when "PreserveVariableNames" is set as "UserNames".

https://www.mathworks.com/help/coder/ref/coder.embeddedcodeconfig.html

[Felipe Herrera]

Thanks. I was able to generate the code without MATLAB coder changing the variables names. I want to integrate this code into a S-function builder to test it in Simulink. However, the MATLAB coder generates to many files. Embedded coder generates only four files, so it is more manageable. I have already set the option

coder.FilePartitionMethod = "SingleFile";

into my script, but it didn't reduce the files. Is there a way to reduce the amount of files generated by the MATLAB coder?

As the MATLAB coder generates a static library, some answers in the forum propose to use the C caller in Simulink. However, I found the setup of the C caller really difficult. I was hoping that it would be a plug-and-play aproach where I browse the file into the folder where it is stored and simulink would take care of the rest. However, it wasn't the case and I'm feeling like a fish out of water with this. Not my area really.

[Fangjun Jiang]

Yes. Controlling the code generation exactly as what you want regarding number of files, variable names etc. is sometimes difficult. I would think your best shot is still using the MATLAB Function block in Simulink and generating code as a whole from Simulink. Did you try that "PreserveVariableNames" in the embedded coder configuration? https://www.mathworks.com/help/coder/ref/coder.embeddedcodeconfig.html

Contact the Mathworks tech support for direct assistance.

[Felipe Herrera]

Yes, I tried to control code generation in simulink using Embedded Coder Config options. However, I couldn't find a way to tell simulink to actually use those configuration parameters. I tried using SwitchTarget, and it did apply the parameters but it didn't last long. When the m-script used to inicialize the parameters stop executing, simulink configuration returns to its previous values.

I will contact Mathwords tech support, thank for your assistance.