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Merged
merged 1 commit into from
Oct 14, 2020
Merged

runtime: add cheap atomic condition variable #1172

merged 1 commit into from
Oct 14, 2020

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@niaow
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@niaow niaow commented Jun 15, 2020

Earlier on slack @aykevl suggested that something like this would be needed.

Usage example with systick:

package main

import (
	"device/arm"
	"machine"
	"runtime"
)

var cond runtime.Cond

func main() {
	machine.LED.Configure(machine.PinConfig{Mode: machine.PinOutput})

	// timer fires 10 times per second
	arm.SetupSystemTimer(machine.CPUFrequency() / 10)

	for {
		machine.LED.Low()
		cond.Wait()
		machine.LED.High()
		cond.Wait()
	}
}

//export SysTick_Handler
func timer_isr() {
	cond.Notify()
}

Current issues making this WIP/not ready:

  1. runtime: make channels work in interrupts #1142 needs to be merged
  2. Where should this go? It was originally in runtime/interrupt, but that caused an import cycle.
  3. The no-scheduler implementation is still suboptimal (it should wait instead of using a polling loop).

@niaow niaow added this to the v0.15 milestone Jun 27, 2020
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niaow commented Jul 12, 2020

The no-scheduler implementation is still suboptimal (it should wait instead of using a polling loop).

This part has now been resolved.

@niaow
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niaow commented Jul 12, 2020

Where should this go?

@aykevl any opinion?

@deadprogram
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deadprogram commented Sep 12, 2020

Reminder to @aykevl and @niaow about this PR. 😺

@niaow niaow marked this pull request as ready for review September 12, 2020 14:29
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niaow commented Sep 12, 2020

This should work decently now. However, my computer isn't recognizing my ARM boards right now so I have not been able to test on hardware.

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deadprogram commented Sep 12, 2020

Tested with the provided example on ATSAMD21 board (Circuit Playground Express) and then also on nrf52840 (Circuit Playground Bluefruit) and both worked exactly as expected.

@aykevl any feedback before this gets merged?

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deadprogram commented Oct 14, 2020

We really need this for something specific. Code looks good, and works as promised, so now merging. Thanks @niaow for this feature!

@deadprogram deadprogram merged commit ed9b97c into tinygo-org:dev Oct 14, 2020
@deadprogram deadprogram mentioned this pull request Oct 14, 2020
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@aykevl aykevl mentioned this pull request Oct 14, 2020
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@niaow niaow mentioned this pull request May 11, 2021
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@aykevl aykevl mentioned this pull request Dec 1, 2024
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@niaow @deadprogram