8000 utimeq overflows after reaching 0x3fffffff, while ticks_ms values will grow larger · Issue #232 · pycom/pycom-micropython-sigfox · GitHub
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utimeq overflows after reaching 0x3fffffff, while ticks_ms values will grow larger #232

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martijnthe opened this issue Dec 5, 2018 · 3 comments
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utimeq overflows after reaching 0x3fffffff, while ticks_ms values will grow larger #232

martijnthe opened this issue Dec 5, 2018 · 3 comments

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@martijnthe
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utimeq is mostly used in conjunction with ticks_ms() in uasyncio, where "timestamps" generated by ticks_ms() are passed into the queue to sort the elements in the queue.

What the problem is depends a bit on what you deem "correct". The values returned from ticks_ms() can grow larger than utimeq's fields to hold the time values. peektime() can only return values up to 0x3fffffff ((1 << 30) - 1).

If one attempts to use uasyncio on a Pycom board, sooner or later (after 12.42 days when the overflow happens) mayhem will happen because of this wrap-around...

I guess one fix would be to make ticks_ms() wrap at 0x3fffffff as well and fix ticks_diff() to return serial distance (taking wrap-arounds into account) -- see #231. Another could be to change utimeq to be able to handle larger time values.

Related issues: #231, #112.

cc @robert-hh @iwahdan88
@martijnthe martijnthe changed the title utimeq overflows after reaching 0x3fffffff, while ticks_ms values will grows larger utimeq overflows after reaching 0x3fffffff, while ticks_ms values will grow larger Dec 5, 2018
@martijnthe
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Part of the problem: micropython/micropython#4336

@robert-hh
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See alsomy comment here: #231

@husigeza
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husigeza commented Jan 5, 2019

Hello!
PR235 will fix this problem, thanks @robert-hh for the fix.

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@martijnthe @husigeza @iwahdan88 @robert-hh
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