Re: [hatari-devel] New cycle exact bus sharing for blitter

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On Sun, 13 Aug 2017, Nicolas Pomarède wrote:

Le 11/08/2017 à 16:23, Nicolas Pomarède a écrit :

I just committed some new blitter code that will handle bus sharing between blitter and CPU as a real STE (or STF with a blitter) would do.

This cycle accurate blitter mode will be enabled when using the 68000 in CE mode (as for emulating an STE)


as an extra funny feature, I added a "blitter-o-meter" to the status bar.

Depending on the blitter's usage during each VBL (from 0 to 100 %), the blitter's led will be filled with a lighter color.

For example, check "We Were" or the latest DHS demos (Sea of colors, ...) to see it in action.

This is only for the SDL UI version, someone will need to add it to the OSX version if people want it too.

By the way Anders, while checking Sommarhack 2017 invitation demo in mega STE mode, I noticed the blitter-plasma part is shifted. Is this supposed to work on real mega STE, or is this what the readme meant by "the plasma is eight pixels shorter every scanline, due to a slower blitter" ?


Thanks for the blitter updates, it's very useful for some kind of code.

The invitation works on Mega STe, but as the doc writes it's one write shorter per line. Question is what you mean with shifted? As the plasma is 8 px shorted, I centered it with an extra nop, is that what you mean by shifted?

What the hell, let's try Troeds latest Hatari and see what it looks like in MSTe mode...

Now tested, it looks like expected with 5 px of bg from the previous line. In hindsight, for the emulator sake, it would perhaps have been better to not have the center-nop and let the colour at the right border become "long". At the time of doing the demo, I'm not sure Hatari had a (working) Mega STe mode, if it did, I was unaware of it. 505 did the Mega STe testings and it's very likely that his monitor didn't see that far out in the border.

I've now got the fancy OSSC to my STe, I'll do some measurements to see how much borders it will see, and if the mythical extra "troed" scanlines at the bottom will show :)

Anders Eriksson

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