Trouble inlining C-Mex S-Functions
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Hello everyone!
After spending quite a long time fighting with this issue I think I’m at the point of having to ask for some help to clear up my confussion. I consulted the documentation, examples and discussions, and thought I understood, but my failure to get it working proves the contrary.
So: I want to inline a quite heavy iterative algorithm that was given to me in form of a C-Mex S-Function. I’m working with code generation for embedded microcontroller targets, compiling the code in the corresponding IDE (TI CCSv3.3 and CCSv5). Everything was working fine until I decided to implement this S-Function and to inline it, mainly to avoid the S-Function API and improve the efficiency on target.
Writing a wohle new TLC is not a reasonable option for me. So I thought I could use the Legacy Code Tool. Am I wrong here and is this just thought for “pure” C code? Maybe I still could use it later on for registry operations, but first I need to implement the algorithm.
All the legacy_code commands seemed to work (sfcn_cmex_generate, slblock_generate, sfcn_tlc_generate…) except the ‘compile’ which failed with docens of messages like: “sfun_orig.obj : error LNK2005: _ssSetStateAbsTol already defined in ex_sfun_out.obj”
I’m therefore assuming I must use a wrapper. I understand this requires writing a small TLC to embodie the calling function. This shouldn’t be a big deal, as the algorithm has 2 inputs, 1 output, 1 discrite inherited sample time and just needs a couple of values from the previous steps... but I still didn’t manage it. Using it as a common level-2 C-Mex S-Functions works fine.
I’m even starting to think of “extracting” the c routines of the s-function and create a regular .c to work with, but I’m not sure if it’s a good solution... and maybe it’s an unnecessary mess.
Hopefully someone will give me a clue… so that I know in which way to focus my efforts.. .
Regards, and thanks a lot in advance!
Martin
2 个评论
Kaustubha Govind
2013-2-19
Are you using functions like ssSetStateAbsTol in your C code? If yes, that may be the issue. The code that you give to the Legacy Code Tool is supposed to be something that can run independently (including on an embedded target).
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Kaustubha Govind
2013-3-13
I think you might be using the Legacy Code Tool incorrectly - the code that you supply to the tool is supposed to be standalone C code (probably some legacy algorithms that you inherited which you want to run as part of a Simulink model), and the tool generates the "wrapper" S-function interface like mdlInitializeSizes, mdlOutputs, etc. along with TLC code which basically just asks Simulink Coder to generates calls into your standalone C code. I wonder if it might be easier if you manually create the TLC file, unless there is an easy way to separate out the algorithm part of your S-function into standalone C code, and then generate a new S-function and TLC using Legacy Code Tool or S-function Builder.
4 个评论
Kaustubha Govind
2013-3-15
Martin: I don't know of a significant difference in the generated TLC for performance - I think you can use whatever you find more convenient.
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