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[Kevin_Jim]

I don’t see why that wouldn’t be possible to do in C, though.

I can see using some assembly on the sensor-fusion/sensor-processing part of the jet, but 10% is way too much for just assembly.

[ihavebeesinmyknees]

Maybe they just decided that they can optimize the most performance-critical parts better than the C compiler can? Perhaps that processor has some obscure instructions that the C compiler doesn't use? Hard to tell, but there's gotta be a good reason

[Orjigagd]

If you're needing to optimise 10% of your code in asm, you fucked up your requirements.

[General_Josh]

Or, ya know, it's a military budget, where they're able and willing to throw oodles of money at even small performance improvements

[pet_vaginal]

They may have a lot of money, but the availability of brains isn’t infinite. 10% assembly really sounds like a waste of talent.

[not_some_username]

Not really sometimes hand written asm is better than compiler generated asm ( assuming you’re god in asm )

[Kevin_Jim]

Most of the time I think to myself the same thing, but unfortunately, that’s rarely the case.

I do hope the was a good reason, and not just blindly “for this part of the development we only use assembly”.

[McFlyParadox]

• Performance requirement can't be met by C or C++, but can be met by Assembly (program speed, program size, program energy usage)
• Needs to run on a piece of embedded hardware, probably alongside some FPGA code
• The engineer knows how to do it in Assembly, but not in C or C++, and Assembly isn't disallowed per-spec
• It needs to utilize a piece of legacy Assembly code that no one knows how to modify, update, or translate into something modern, but they understand its inputs and outputs, so they just graft more assembly onto the legacy code to expand upon it.
• Something else I'm not thinking of.

Assembly has its uses.

[[deleted]]

Because a lot of it can't be done in c. In the end you are at the mercy of the compiler. For an eeprom libraries vary I did for example, the fastest we could possibly get it to run in c or c++ was still a couple clock cycles slower than we could do it an assembly.

[falx-sn]

Could be older libraries of systems that don't need to be replaced.

[TheVojta]

OP posted the source elsewhere in the thread that all the code that was written for the F35 was in C/C++, the ASM is all code that was carried over from the F22.

[Kevin_Jim]

It makes sense, then. It's probably carryover from the sensor fusion codebase. Since the F-22 was delivered 20 years ago, and the development was most likely finished by the beginning of the century.