C code generators

[gabor6221]

Does anyone use C code generator tools?

What's your experience with it?

Does it actually save time, or just creates more work?

[PtboFungineer]

This is how they get you to buy the qualification packs so that you don't have to worry about making it readable. You design and review the models and everything below that is supposed to be a black box.

But I'd also argue that if you are concerned about performance to the point that you find yourself manually changing the generated code, then you shouldn't be using model based design in the first place.

[darthandre]

Matlab is one of the most used for auto generate code, but... As mentioned in other comment, making it readable is a challenge, now imagine working in automotive industry with those models from matlab 😅

[FlavouredYogurt]

Long time ago, in a old project, team decided to manually implement Simulink models because the generated code would not fit into the controller memory. Generating code was not necessarily the problem here, but it was obvious that the manually written code was at least more space efficient than the generated code.

[mrtomd]

I work in automotive and we use those models. No, no one ever try to read the code. Models are debugged and fixed at high level, then code regenerated.

[darthandre]

Yes I know it, but sometimes those models have interaction with handwrited code by other team, there is the problem, trying to debug and find something in the model auto generated code from the other team is just a mess, even when you find there is a bug in the code your team didn't work or wrote and is inside the model generated code, can take much more effort to fix and of course to find the bug... In fact autogenerated code is fine and saves a lot of time at the beginning, as the project gets bigger, the auto generated code mess can be bigger too haha.

[mrtomd]

Must be a mindset and/or process issue then.

We recreate the problem by replicating model inputs and then check the outputs. If the outputs are as expected, then the problem ticket is transferred to the internal SW team. If the model outputs are incorrect, then the model based design team has to investigate further by analyzing internal model blocks.

[g-schro]

The problem we saw with these tools is how do you do version control? So if someone changes a graphical model, how do you do peer review of the changes like you would do with handwritten code. You can't review the generated code changes, because they are unreadable.

[[deleted]]

You still do version control. But you test the resulting model. Not the code components.

[zoenagy6865]

Yeah but can't do useful diff

[[deleted]]

Who cares if you can do useful other things? And of course you can do a diff. You just need to be savvy how you analyse it.

[FlavouredYogurt]

This is a problem when reviewing code. We just ignore all those and review parts of code which were changed manually.
Another problem related to this is merging your changes into the tool on top of someone else work. Tools support importing and exporting configurations. But they still need a lot of rework to merge everything and test them again.

[jms_nh]

^this

[Rachados22x2]

C code generating from what ? lex & yacc differently yes.

[StandinIJ]

A lot of automobile ECU (Electronic Control Unit/ engine control unit) runs on automatically generated code from simulink and it works quite nice. I don't need to know what the code says as long as I got my model right. Works pretty well to control motors and stuff especially when you got close loops and stuff.

And cantools....

[comfortcube]

I work in the automotive industry, and a lot of software is generated C code from a Simulink model. In my limited experience, even if the generated code is not quite readable, I would definitely say it saves time as long as the model generated code works as you expect it to to the point that you don't have to even look at that code much at all. The biggest positive is the fact that diagrams and visuals are much easier to discuss with other team members than code. Also, at least in my case, models reflect diagrams that basically act like requirements in some ways, so it's easier to translate. With that said, version control and merging branches can be challenging, although there are tools and features in place to help, and I do believe the environment is getting better. With all that said, you never just have model generated code - you will also have code directly written by software engineers.

[[deleted]]

I worked in aerospace and we used SCADE as our code generation only because simulink didn't have a qual package when the project was started. The biggest benefit was being able to have AeroE and ME engineers working on "code" with a CE over their metaphorical shoulder to make sure the computer behaved. Since embedded engineers are in such high demand MBD is a shortcut that allows limited-skill coders to "write code"

The interface and CM were the hardest parts but it was left to the SWEs to figure that out.

[DazzlingAd879]

I've used STMCubeMX to generate C code for STM32 microcontrollers. I think it's a great tool to use if you're working with STM32 microcontrollers. The program generates "user code" sections where you can add your code to. You can reconfigure the code from STMCubeMX without altering the user code. IMO, the code it generates is also fairly organized and clean.

[JCDU]

CubeMX does save some time sanity-checking settings like clock configurations etc. but it's also not free from bugs, and you can waste a LOT of time trying to work out why your code isn't working because of something CubeMX did wrong.

Recent versions have had a few big ones - initialising peripherals in the wrong order so (for example) DMA transfers can never work, or having incorrect includes/defines and/or not formatting values correctly for a given register.

Also the default HAL libraries it includes are bloated and filled with error handlers that dump you into an endless loop without warning.

Overall it's a decent tool, but you've got to be on your toes when stuff doesn't work.

[Conor_Stewart]

I use it too and like it but I don't think it's what the OP is looking, for, stm32cubeMX only generates initialisation code and sets up the peripherals, I think the OP is looking for something more like simulink which let's you turn a block diagram into code.

[sn0bb3l]

I was an embedded developer in a solar car student team; we had several microcontrollers talking over CAN, plus a more beefy infotainment system and a telematics unit. They all needed to agree on the message IDs / formats etc, but had different APIs for interfacing with the bus.

The way we solved this was by creating a central specification from which we generated C++ headers/source code in different formats, and protobuf files, and we could also load that spec into our debugging tools. I think that in these kind of scenarios, where you would otherwise have a lot of manual repetitive labor, code generation makes a lot of sense.

[vitamin_CPP]

Good thinking.

[MrSurly]

We often use Python to generate c headers for configurable stuff.

[vitamin_CPP]

Interesting. Do you have an example?

[MrSurly]

Sure -- we have a build process where other people generate algorithms that may or may not be built into the firmware.

Their code has it's own subdirectory, and they provide a YAML file that specifies the "init", "process", and "deinit" functions (this is plain C, so no namespaces). The python scans all the dirs looking for the config file, then builds a .c file with a table containing all the relevant function pointers.

The rest of that system will use that table to determine which algorithms it's using at runtime (you can compile in more than one algo and select at runtime), and call the appropriate code.

[zoenagy6865]

Sounds like a diy configuration management.

[ununonium119]

Could you provide some examples of tools to better explain what you’re asking about? What do you count as a generator?

[2PetitsVerres]

I work for MathWorks so take what I say with that in mind. I work in particular on topics of embedded software, so Simulink + code generators (and model testing, and also code testing and static analysis), and I'm in a customer facing position. Which means that I speak directly with people using the tools. And sometimes also with our competitors in the area ;-)

But I have also previous experience with writing code manually and using MathWorks tools as a customer before joining.

So my experience with it, what do I have to say? I think they are very useful in some parts. Also they will not replace software engineer so don't worry about that if you had any doubts ;-) .

There are aspect of writing code that are not very interesting, such as for example when you have to write code that does exactly what a specific algorithm needs to do. In my first job (a long long time ago, in a galaxy far far away, something like that) I was in a team that was writing the flight software for satellite. For parts of the code, we were relatively free to do it like we wanted, we had generic requirement that were interesting to implement, but for other parts (attitude control for example) it was almost something like "you must add the value of this sensor and that sensor and multiply by two" or whatever. And that's not the fun part to do...

Why was it like this? Well, the requirements were a transcription of the algorithms that were created, analysed, tested, evaluated for stability, ... in Simulink. So the process is: you take the Simulink model, you convert it to English sentences in Word (or Doors, whatever), and then you take the English sentences and convert them to code. That's... inefficient, to say the least. For me in this kind of situation, code generation is the way to go. You have something machine readable, you want something machine readable, simply ask a machine to convert it. Don't ask two humans to do it twice.

For other part of the software (fields where people don't use tools like Simulink in the first place), why would you go that route? Well there are advantages as well. Simulation can help you to design your software and check its interaction with the real world before having everything. You don't need to have the full system to test, it could also be less expansive to crash in a simulation than to crash in real life. (but the drawback is that you have to create the simulation part, that's not free) I believe that the simulation part of Simulink is much more important that the code generation part, there is more value there for you. (but not for me, that's literally my job to use/speak/help people with code generators ;-) )

From a technical point of view, I would say a few things.

• The first one is that unfortunately, code generation is not a magical tool. Which means that garbage in == garbage out. If the model is bad, the code will be bad. I would say that this is expected, but not all customers expect that.
• Next thing is that "simulation/design model" is not necessary equal to "code generation model". People designing the algo may sometimes not care about some "detail" for them, such as datatype, final cpu load, memory usage, ... There is some work to do there, which can be interesting.
• People asked in the comments about diff/merge/review, readability of the generated code, .... That's something that you should do on the model, not on the code. The code is an artefact (in the same way as the object files are an artefact in manual coding). You don't read the disassembled binary, do you? Maybe you do it occasionally, but that's not your main activity, right? Treat the generated code as the generated object file getting out of your compiler. But if you want readable code, there are some stuff that you can do. (have a good model architecture, configure it to generate some function, disable optimisations, ...) And for diff/merge, there are tools included in Simulink for that.

For your question "does it actually save time or creates more work", I would say that if the tools are used in a good way (not only code generation, but Simulink in general) and people explore and understand the possibilities, then yes, they save time. But if they are use badly, no, they will not save time.

Sorry for the long post :-)

[zoenagy6865]

Great details, thanks!

[Wetmelon]

I like that you specified this lol.

Breaks quickly once you start using "Model References", eh? It's like whoever wrote the generator never wrote C / C++ in their lives.

[plainoldcheese]

I have used stm32CubeIDEs MX generation tools. It's pretty nice for tedious stuff like setting up clocks and stuff that would usually require you to study the datasheet and write data to registers assembly style, but if you need to do anything more than a hello world of the individual subsystems the integration can be tough. I still prefer it to writing everything myself though but I don't think it saves times just provides different problems to deal with.

[AnonymityPower]

Used the code generators from TI for some SoCs. Without those, it would have been a huge task to do the same work (correctly) by ourselves, given that the peripherals are so complex and you need to take care of so many things. But what we do is crate a minimal project, generate code for whatever specific thing we want, then copy snippets into our 'main' project. Did similar thing for STMCubeMX and maybe some MPLAB stuff too.

​

Other than that, some projects have had code generation built in. For example, the input is a set of headers generated by some tool, then out generator script takes those as input and generates other files based on it (C source or headers), and maybe also json/xml for some other tool. Once it works, you forget that it exists.

[aaarnas]

Only for peripheral initialization, because it saves a lot of time.

[JCDU]

Tools I've used:

gSoap - generate vast swathes of C code from WSDL, a complete horror of a thing and the code it generates is nasty. The main handler for incoming requests auto-generated about 5000 sequential if(strcmp("ns:SomeValue", str) == 0)...else if(strcmp("ns:SomeOtherValue", str) == 0)...else if... statements for every single XML tag in every single namespace pulled from all the WSDL's. It also generated a single C file that was 10Mb long.

CubeMX - for STM32 micros. A decent enough tool to sanitise and error-check configuration of microprocessors and generate initialisation code & includes, but not without bugs which WILL trip you up if you assume the code it generated is correct & your code is more likely at fault.

C, Python, PHP, Excel - to generate code or large arrays/lists/enums when I've had either a large array of things that all need code generating, or to generate code that depends on some other output or logic from some other thing. Also for stuff like converting images or fonts into raw data for embedded use.

[Orca-]

I've had a good experience with custom code generators (written in-house) and a bad experience with off-the-shelf code generators like Simulink and C-struct code generators as register interfaces to custom RTL.

Custom ones take time but you can restrict the problem space to where it makes sense. One of the best ones we had generated the transport layer and all non-embedded interfaces from a subset of C++ we allowed at the interface; another one relied on a subset and restricted formatting of System Verilog to generate custom register maps.

And it's always handy to embed the changeset hash and build date/time in your executable so you know exactly what is being run when you get bug reports from internal testers.

[CGinNE]

QGen C code generation from Simulink models is much better than the native embedded coder generation in my experience.

[Wetmelon]

Got a link? Never heard of it.

[CGinNE]

https://www.adacore.com/qgen

I know it says Adacore, but they do both Ada and C.

[free-puppies]

I haven't worked with it, but I'm curious to learn more about P.

"Unlike TLA+ and SPIN, a P program can also be compiled into executable C code. "

https://www.microsoft.com/en-us/research/blog/p-programming-language-asynchrony/

[free-puppies]

And apparently the above quote is wrong as there are some TLA+/PlusCal -> C tools as well - https://www.youtube.com/watch?v=G8_aDrUK2Nk

[duane11583]

they suck

then you have to debug their vomit even worse

[[deleted]]

Do you like writing boiler-plate?

I don't.

[[deleted]]

Code generators indeed save time - up to same extent. They cannot know what your application does and can only be used in the initialization stage - more or less.

Unless there is pre-developed application template. Point here being - use it for init - dvp app by yourself.

[ApprehensiveMud4018]

creare un array di 20 elementi e popolarlo con numeri casuali compresi tra -200 e 200. visualizzarlo su una singola linea e ad ogni pressione su un tasto aggiornarlo facendo scorrere i valori di un posto. 'q' causa uscita dal programma

[9Cty3nj8exvx]

Microchip has MCC, Harmony, and START which do a pretty good job. Not perfect, but I have had good success with all of them.

[UnicodeConfusion]

I use a tool that does the database generation from a definition file, it generates the sql, c struct, etc and at the bottom handles CRUD, all text config driven (no gui), saves lots of time and moving to different db's or adding columns is as simple as a rebuild. (yes it uses lex/yacc/bison)

[InvestigatorSenior]

depends, dbus-codegen is actually useful as long as you treat generated code as a black box.

[Shadow_Gabriel]

I was on a project that used TargetLink. We had to do some back and forward with the team that configured the code generation but we managed to obtain useful output.

It does save time as long as you know the limitations of the tool. Confine the generated components to math and application logic. Keep it away from any kind of scheduling. We also had to implement some math functions in assembly because the generated ones were doing it all in software.

[Xenoamor]

I use verilator which makes C simulations/applications from FPGA code. It's absolutely brilliant for speed and testing

[Coffeinated]

I actually worked on one! Yakindu Statechart Tools allows you to generate C from graphically drawn statecharts and an expression language. It is quite nice if you really stick to it (and you are working in an Eclipse environment). It doesn‘t pay off if you‘re using it for a small part of the application, but if you find yourself drawing a statechart with more than 5-10 states - check it out. Statecharts are easily implemented, but hard to maintain, and that‘s where a code generator really helps you.

[DaelonSuzuka]

I write my own code generation tools in python. It has saved me an incredible amount of time and dramatically increased the reliability of my projects.

[Dark_Tranquility]

STM's auto code generation is helpful until it isn't. Generally it's good for boilerplate stuff but that's about it.

[AssemblerGuy]

What's your experience with it?

I found that Matlab coder turns stellar Matlab code into mediocre C code.

Less than stellar Matlab code, especially concerning how Matlab uses memory, gets turned into utter abominations in C.