Ah yes. The speedup-loop.
https://thedailywtf.com/articles/The-Speedup-LoopI think some compilers will just drop that in the optimization step.
Real pain in the ass when you’re in embedded and your carefully placed NOPs get stripped
On microcontrollers that might be a valid approach.
I’ve written these cycle-perfect sleep loops before.
It gets really complicated if you want to account for time spent in interrupt handlers.
But then I gotta buy a space heater too…
Microcontrollers run 100% of the time even while sleeping.
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.
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
Javascript enters chat:
await new Promise(r => setTimeout(r, 2000));Which is somehow even worse.
Tell the CPU to wait for you?
Na, keep the CPU busy with useless crap till you need it.
Have you considered a career in middle management
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.
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…I mean maybe in an early interpreted language like BASIC… even the Intel 8086 could count to 1000 in a fraction of a second
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.
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.
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.
