Add fps rate limiter

[rickgaiser]

@freshollie can you try this?

Untested but should work. @fjtrujy what do you think? Can be added for non-HIRES as well.

[freshollie]

I'll have a go this weekend :)

I'll also use this time to determine if changing the line order for 1080i helps my TV 🤔

[freshollie]

Yep works great, having this in would be really nice!

static void gfx_ps2_swap_buffers_end(void) {
    /* How SM64 expect to run at 30 PFS we need to wait for 2 vsync */
    if (use_hires) {
        gsKit_hires_flip_ext(gs_global, GSFLIP_RATE_LIMIT_2);
    } else {
        gsKit_sync(gs_global);
        gsKit_flip(gs_global);
    }

    gsKit_queue_exec(gs_global);
    gsKit_TexManager_nextFrame(gs_global);
}

I used it like this which I think is correct?

No FPS issues in levels now I have this on

[rickgaiser]

You need to use gsKit_queue_exec(gs_global); for non-hires ONLY. With HIRES the queue is executed by the HIRES thread 120x per second for 2 passes what you're using now.

What you're doing causes 1 redundant 'pass', so removing it will make the game run a little smoother.

[freshollie]

Done. Though it did run fine without it

[freshollie]

@rickgaiser I think also adding for SD will be a good idea, but otherwise good to merge IMO

[rickgaiser]

Yes, I've already implemented that partially. Will try to finish when I have time.

[rickgaiser]

What I would like is a complete integration of hires/non-hires. Then instead of gsKit_hires_flip_ext have only gsKit_flip_ext that works for all modes. But this requires using the vsync interrupt in gsKit internally when not using hires, instead of allowing applications to register the vsync interrupt. Making this a breaking change.

There's more functions from hires that can be removed in the same way. That would also simplify applications no longer needing the if/else in a few places for SD/HD.

I tried to do this but it's taking me too much time so please review this PR as-is and leave the above as a note for those interested to tackle this issue.

[freshollie]

Makes sense. Though I think to make this non breaking couldn't this be a different function you call for handling on both modes?

[rickgaiser]

Makes sense. Though I think to make this non breaking couldn't this be a different function you call for handling on both modes?

My design idea was:

• HIRES uses HSync interrupt, from there it generates a (more relaxed) Vsync interrupt
• non-HIRES must register to the VSync interrupt

Have both interrupts call a generic function like:

void isr_vsync_handler() {
  iFrameCounter++;
  iSignalSema(iVSyncSema);
}

Then have a generic gsKit_flip_ext function that uses the iFrameCounter and iVSyncSema to create all needed vsyncs and rate limits, for both SD/HD.

The issue with SD:
You cannot always register to the VSync interrupt, becouse some apps already use that.
You cannot count frames without VSync interrupt.

Perhaps the solution is to make VSync interrupt go through a gsKit function first, before calling the registered function.
https://github.com/ps2dev/gsKit/blob/df911e9fa76177ae606ee6f09482f8fd9d910250/ee/gs/src/gsCore.c#L200L212

[fjtrujy]

LGTM