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Sleep() at home (programming.dev)
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[-] EisFrei@lemmy.world 88 points 9 months ago
[-] tryptaminev@feddit.de 21 points 9 months ago

This is brilliant.

[-] bangupjobasusual@sh.itjust.works 81 points 9 months ago

I think some compilers will just drop that in the optimization step.

[-] ryannathans@aussie.zone 27 points 9 months ago

Real pain in the ass when you're in embedded and your carefully placed NOPs get stripped

[-] vrighter@discuss.tchncs.de 5 points 9 months ago

asm("nop");

[-] wreckedcarzz@lemmy.world 17 points 9 months ago

Homer: "oh yeah speed ~~holes~~ sleep"

[-] jaybone@lemmy.world 3 points 9 months ago

Sleep holes

[-] Darkassassin07@lemmy.ca 68 points 9 months ago

Tell the CPU to wait for you?

Na, keep the CPU busy with useless crap till you need it.

[-] jaybone@lemmy.world 26 points 9 months ago

Fuck those other processes. I want to hear that fan.

[-] leclownfou@sh.itjust.works 4 points 9 months ago

I paid good money for my fan, I want to know it's working!

[-] kogasa@programming.dev 24 points 9 months ago

Have you considered a career in middle management

[-] aksdb@lemmy.world 25 points 9 months ago

On microcontrollers that might be a valid approach.

[-] kevincox@lemmy.ml 10 points 9 months ago

I've written these cycle-perfect sleep loops before.

It gets really complicated if you want to account for time spent in interrupt handlers.

[-] aksdb@lemmy.world 2 points 9 months ago

Thankfully I didn't need high precision realtime. I just needed to wait a few seconds for serial comm.

[-] Darkassassin07@lemmy.ca 1 points 9 months ago

But then I gotta buy a space heater too...

[-] YIj54yALOJxEsY20eU@lemm.ee 4 points 9 months ago

Microcontrollers run 100% of the time even while sleeping.

[-] towerful@programming.dev 3 points 9 months ago

Nah, some MCUs have low power modes.
ESP32 has 5 of them, from disabling fancy features, throttling the clock, even delegating to an ultra low power coprocessor, or just going to sleep until a pin wakes it up again. It can go from 240mA to 150uA and still process things, or sleep for only 5uA.

[-] YIj54yALOJxEsY20eU@lemm.ee 3 points 9 months ago* (last edited 9 months ago)

Nah, Sleeping != Low power mode. The now obsolete ATmega328 has a low power mode.

[-] Matty_r@programming.dev 13 points 9 months ago

This should be the new isEven()/isOdd(). Calculate the speed of the CPU and use that to determine how long it might take to achieve a 'sleep' of a required time.

[-] henfredemars@infosec.pub 11 points 9 months ago

I took an embedded hardware class where specifically we were required to manually calculate our sleeps or use interrupts and timers rather than using a library function to do it for us.

[-] vcmj@programming.dev 10 points 9 months ago* (last edited 9 months ago)
[-] drmoose@lemmy.world 9 points 9 months ago* (last edited 9 months ago)

Javascript enters chat:

await new Promise(r => setTimeout(r, 2000));

Which is somehow even worse.

[-] sbv@sh.itjust.works 4 points 9 months ago

As someone who likes to use the CPU, I don't think it's worse.

[-] KairuByte@lemmy.dbzer0.com 2 points 9 months ago

I mean, it’s certainly better than pre-2015.

[-] ExtraMedicated@lemmy.world 5 points 9 months ago

I actually remember the teacher having us do this in high school. I tried it again a few years later and it didn't really work anymore.

[-] snaggen@programming.dev 13 points 9 months ago

On my first programming lesson, we were taught that 1 second sleep was for i = 1 to 1000 😀, computers was not that fast back then...

[-] aBundleOfFerrets@sh.itjust.works 3 points 9 months ago

I mean maybe in an early interpreted language like BASIC… even the Intel 8086 could count to 1000 in a fraction of a second

[-] snaggen@programming.dev 4 points 9 months ago

This was in 1985, on a ABC80, a Swedish computer with a 3 MHz CPU. So, in theory it would be much faster, but I assume there were many performance losses (slow basic interpretor and thing like that) so that for loop got close enough to a second for us to use.

https://en.m.wikipedia.org/wiki/ABC_80

[-] lauha@lemmy.one 4 points 9 months ago

I can relate. We have breaks ate work too.

[-] Socsa@sh.itjust.works 4 points 9 months ago

You gotta measure the latency of the first loop.

[-] Bronco1676@lemmy.ml 2 points 9 months ago

I just measured it, and this takes 0.17 seconds. And it's really reliable, I added another zero to that number and it was 1.7 seconds

this post was submitted on 24 Jan 2024
577 points (97.4% liked)

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