SpritesMind.Net

Do you plan to fix this on the xgm side, by allowing interrupts during fades, or by allowing interrupts + clearing the pointers during the fade?

Yes, they most certainly are made in quantity. Even if you care about singles pricing: 32kb, single pricing at 4 UK cents: http://uk.rs-online.com/web/p/sram-memory-chips/0538142/ (it's been a while since I did electronics, so no guarantee that chip is straight Gen compatible. Just to show the gener...

Sure, but in 2016 that costs about 0.15 cents

I'd like a way to disable it completely. Any game with a high score would use SRAM.

Would it be enough to edit boot/sega.s, such that "bne.s SkipSetup" became "bne.s Continue"?

I want a soft-reset to be exactly the same as a hard reset. I see sgdk currently doesn't zero anything on a soft reset. How do I change it? Where is the reset vector set up?

I doubt it'll be of much help though since I'm 100% sure it was optimized for modern architectures. I had considered once making a fast 32-bit integer to string subroutine in assembly, but again it requires the BCD instructions ( and a good bunch of look-up tables). At least could be called as a no...

I measured the DMA queue, and it took about 19 lines. Seems I had some too long frames on rarely executed functions, optimized a bit, let's see if that takes care of it.

Have you tried the number-to-string function from Facebook (IIRC)?

It used a lot of ifs instead of division, and it was faster on x86_64.

I think you can even measure it using background color change but really the overhead is small enough... How would you measure something that lasts less than a frame with a color change? Emulators only display at 60fps, hw displays at 60fps, and even if you had a 200Hz screen, you'd also need a hig...

Hm, so 7.2kb if you use XGM, and 6.8kb with the XGM extra protection. I ask about this, because in a game I was writing 4.4kb in the dma queue, and it was lagging on hw. So I wondered if the XGM overhead was big enough to cause that. If the overhead would indeed drop the budget to just 6.8kb, then I...

In _vint_callback(): if (vintp & PROCESS_XGM_TASK) XGM_doVBlankProcess(); // dma processing if (vintp & PROCESS_DMA_TASK) { // DMA protection for XGM driver if (currentDriver == Z80_DRIVER_XGM) { SND_set68KBUSProtection_XGM(TRUE); // delay enabled ? --> wait a bit to improve PCM playback (test on SO...

The docs say a NTSC system can DMA 7.6kb per vsync. Since XGM does some processing there, and the DMA protection also affects some, what is the safe DMA budget when using XGM?

In other words, what is the worst-case amount XGM will steal from the DMA budget?

Is it perhaps because the fade disables interrupts, and XGM does some processing in vint? // process asynchrone fading if (async) VIntProcess |= PROCESS_PALETTE_FADING; // process fading immediatly else { // disable interrupts to avoid VDP accesses conflict SYS_disableInts(); while (VDP_doStepFading...

Taking a closer look, it's not waitVsync(), but just the fade. It happens in multiple emulators. SND_startPlay_XGM(sample); for (i = 0; i < 180; i++) VDP_waitVSync(); // the first time, this short song plays properly VDP_fadeIn(1, 15, intropal, 30, 0); // during the fade, the first note hangs. After...

Whenever there's a fade, or just a loop of "for (i = 0; i < 180; i++) VDP_waitVSync();", the XGM driver just plays one note, as if it's stuck. Known issue? Any workarounds?