Add non-blocking timer module #3
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src/timer.rs
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| fn start<T>(&mut self, count: T) where T: Into<Self::Time> { | ||
| let duration = count.into(); | ||
| debug_assert!(duration.as_secs() < ((u32::MAX as u64 - duration.subsec_micros) / 1_000_000)); |
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I really don't like debug_assert!() calls in embedded because the chances are high that the code will be never exercised.
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error[E0615]: attempted to take value of method `subsec_micros` on type `core::time::Duration`
--> src/timer.rs:27:73
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27 | debug_assert!(duration.as_secs() < ((u32::MAX as u64 - duration.subsec_micros) / 1_000_000));
| ^^^^^^^^^^^^^
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= help: maybe a `()` to call it is missing?
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Yeah, I dislike the debug_assert call too. The alternatives I see are:
assertand hope it gets optimised out- I feel like this isn't too bad a choice, since using
Time = Durationalready relies onCountDown::startbeing inlined and optimised it's highly likely this will be ok.
- I feel like this isn't too bad a choice, since using
- don't assert at all, just have it as a documentation item
- since this is likely to be passed into places that aren't
nrf51specific they won't see this documentation and it's likely to go wrong at some point
- since this is likely to be passed into places that aren't
- Figure out some way to do constrain it at compile time
- I don't think even once const parameters are stable that Rust will be capable of doing this ergonomically
So, if you're happy with it I'll change this to a normal assert
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A normal assert is fine.
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Fixed compile error (I had switched a constant 1 second into the I'll try and push an example tomorrow, unfortunately it'll be going through a |
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I've pushed an example at https://github.com/Nemo157/nrf51-blinker-rs, that uses this + some even more experimental GPIOTE edge detection to wait for a timer to expire or button to be pressed non-blockingly. |
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Okay, that example is rather weird but it works. :-D I'm somewhat curious where you implemented the GPIOTE stuff you're talking about... |
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NB: I've just pushed out a new version 0.4.2 to crates.io. Thanks a lot for your contributions. |
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Nemo157/nrf51-hal@56d7cc6...input-edges I really don’t like the API I added to embedded-hal for it though; I’m going to try and come up with a better design before I’ll be opening PRs to add it. Also want to come up with a compile time checked API for assigning the event channels to avoid the assert. |
As I mentioned in rust-embedded/embedded-hal#59 the
Durationstruct gets compiled out fully in my test code, but I'm still not certain using it is the best idea in case it doesn't.