Accurate timing ~1ms...

[wildfire]

Hi again,

Going back to my emulator (it's a 6510 BTW), I'm now looking at timing accuracy.

My current thought is to use a timer that triggers every 25ms which executes 25000 clock cycles (1Mhz processor) and stalls the virtual CPU until the timer triggers again.

I'm thinking 25ms as any less is not reliable (at least under windows OS) and any more would likely be noticable.

Does anyone have an idea of a better approach?

[Curt Carpenter]

If your windows8 will allow you to use the MMSYSTEM unit, you'll find a better timer there (for multimedia use) than the standard windows timer.  It's been a while, but I think it lets you get down to 5ms or so.

However -- my experience is that windows just isn't real-time friendly no matter what you do 

[wildfire]

Thanks Curt, I'll take a look at that.

Apologies for the brain fart earlier, I've amended my post (obviously it wasn't 400 clock cycles)

[irfanbagus]

just an idea, but works on my opengl application as walkaround to driver bug with vsync

1. find your period (p), 25ms in your case
2. save your current time (t0)
3. run your process
4. save your current time (t1)
5. if t1 less than t0+25ms go to step 4. optional, you can sleep before go to step 4 to save power.
6. t0 = t1 - (t1-t0) mod p
7. go to step 3

[chrnobel]

Can't you use EpikTimer in some way?

Christian

[wildfire]

Would work in conjunction with irfanbagus's method chrnobel,I'll look into it (it may be possible to reduce the period down to 10 or even 5ms with EpikTimer).

Does anyone know if EpikTimer is thread safe?-