Question about Inp ?

[Daniel Ouellette]

Even if it seems to work, it would be better to use Screensync since it also works. When the graphics card doesn't support Screensync, does it just go straight through or can it freeze?

[Daniel Ouellette]

I'll use Screensync if it's safe, that is, if it won't jam. But, the synchronization effect of "A = Inp(&h3da)" is still interesting.

[Imortis]

I'll use Screensync if it's safe, that is, if it won't jam. But, the synchronization effect of "A = Inp(&h3da)" is still interesting.

Why or how would it jam? I have used screensync before, no issues.

[caseih]

Are you using Inp with the Windows 32-bit or 64-bit compiler or are we talking about the DOS version?

[Daniel Ouellette]

I asked the question for Screensync because I have no idea what could be behind this command.

It's Windows 32-bit compiler.

[Daniel Ouellette]

In both cases, Screensync or "A = Inp(&h3da)", the synchronization effect is the same and the execution time is between 0.00001 sec and 0.01790 sec (a bit more sometimes).

0.00001 sec indicates that the graphics card has ended tracing the frame juste at the time of the Screensync command (as well as with "A = Inp(&h3da)"), I have doubts about the efficiency of the synchronization at that moment.

[fxm]

Look at my article and example: Graphics Mode Refresh and Anti-Flickering

[Imortis]

I asked the question for Screensync because I have no idea what could be behind this command.

It's Windows 32-bit compiler.

The windows Screensync translates to roughly this:

Code: Select all

Sleep(1000 / iif(refresh_rate, refresh_rate,60))

So it is just waiting for the set refresh rate of the system, and if that is not set, it just defaults to 1 60th of a second.

[Daniel Ouellette]

I'm not an expert like all of you, so I stupidly used "Sleep(1000 / iif(refresh_rate, refresh_rate,60))" and it doesn't work as well as Screensync and even "A = Inp(&h3da)".

[Daniel Ouellette]

According to my tests, Screensync and "A = Inp(&h3da)" query the hardware. It is not a Sleep related to the refresh rate.

[Imortis]

According to my tests, Screensync and "A = Inp(&h3da)" query the hardware. It is not a Sleep related to the refresh rate.

I don't know what to tell you, then. This is the C code for the graphic library. There is no hardware query during Screensync.

Code: Select all

void fb_hWin32WaitVSync(void)
{
	Sleep(1000 / (__fb_gfx->refresh_rate ? __fb_gfx->refresh_rate : 60));
}

That is all it does in Win32, at least.

The refresh rate is grabbed by the library when you initialize a graphic screen. If you init a screen, it uses that, if you did not, it use 1/60 of a second.

[Daniel Ouellette]

What is Wait Vsync ?

[caseih]

It's the internal FB runtime function that Screensync calls on Windows.

[Daniel Ouellette]

Is it more than a Sleep ?

[Imortis]

Is it more than a Sleep ?

No. That was the point of me posting it. That is exactly what code is executed when you call screensync or wait with the port number.