Emulator too fast !

[lamogui]

The emulator speed is too fast whatever the emulation mode i use (by time or by frame) I can see it with the clock.bin program : the second are half of real second. I don't know if it's my config or other...

[Zardoz89]

I just see it, It's running at double of the speed that should work the clock.

[Zardoz89]

Plus I just see that does something much more problematic. The VM hangs sometimes running clock.bin!

[lamogui]

You think that come from the clock or from the dcpu ?

[Zardoz89]

I need to check what happen here. (Now I going to dinner). Later, I will try to check if the hardware tick() is being called at the desired rate of 100KHz. An alternative is to use sfml timer/clock stuff to measure time, instead of the cpu clock ticks. In the specs not say anything of how the generic clock measures the time.

[Zardoz89]

The VM hangs sometimes running clock.bin!

False alarm! In my desktop, I have yakuake, a Terminal that works like Quake console. It's launched with F12. So every time that I press F12 to hide/show it, the VM go/return of the debug mode. I will inspect what happen with the clock timing and later , i will try to create a window that represent the keyboard. If it have the Focus, then interprets the keyboard events, if not ignores it.

[Zardoz89]

I just checked that gclock had had wrong calculation the max_tick. I fixed it, but I noticed that keeps running too fast. Also I just rechecked and the max_tick and B register values are correct for a interrupt every second, so the VM timming should be bad.

[Zardoz89]

Ok, I think that I discover what happen. GClock measures time using the CPU clock, but the problem is that the CPU running speed isn't contant. Always run a bit faster that should be, thanks rounding errors. For example, with a Delta of 0.017516, the ticks that need to run are 1751, but If you do the math of measure how many time does 1751 ticks in VM time:

1751 * 100000^(-1) = 0.01751  < 0.017516

I will try to fix it, using asMicroseconds() and using a bool flag to add 1 tick every even loop, to keep the time around 100%

[Zardoz89]

Actually I did this:

• Tweaked the main loop to get CPU emulation speeds around 100% (sometimes is 99.9..% other 100.0..)
• Using sf::Clock in generic clock to measure time. Now is more precise, but it keeps running a different speed of what should be. In my computer, now the clock is a bit slower that a real clock .. Deviates at a rate of1 second per minute.

[lamogui]

On my computer the speed is really unstable oscillate between 95% and 177%. I have the sensation that's it slower than normal...

[lamogui]

Now the emulator run at 94%-95% pretty stable and the clock.bin program seems slower (but coherent with the indicated speed) with your recent changes (Sorry i have no time to see your changes monday/tuersday and wenesday, i have busy schedule 8->19)

[Zardoz89]

Now the emulator run at 94%-95% pretty stable I'm my case it's around 97%-102%. Depend of what method of sync you uses. With time method looks more stable. Also, I change refresh rate to 50Hz, because it happens exactly every 2000 cycles of the CPU, instead of 60Hz that need 1666.66... cycles.

(Sorry i have no time to see your changes monday/tuersday and wenesday, i have busy schedule 8->19) Don't worry. Actually I have a lot of free time, so I not stop of coding :P Actually I'm making a floppy drive. It's half working. I only need to talk, in Trillek forums, about the file format to store the disk image. I not like to implement something to find that nobody will use it.

[lamogui]

Emulator is now full speed in timed mode ! 95% in refresh mode, It's the clock which have a problem : the accumation sometimes accumulate 0 instead of 1 or 2 (cause the time resolution on windows is not accurate and the refresh is too speed and the clock is restarted. I fixed that, it's not beautifull but that's should work.

[Zardoz89]

The generic clock keeps being more slower that should be in Linux. I move this to a fresh issue