Re: [hatari-devel] Blitter bug in STe mode

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Hi,

On 6/8/20 11:15 PM, Vincent Rivière wrote:
On 08/06/2020 at 21:30, Eero Tamminen wrote:
I'm not yet fully convinced it's necessarily Hatari specific though.

I can just say that I'm unable to reproduce this bug with Steem SSE or real STe hardware. It would be rather incredible if the problem was not caused by Hatari. Only difference could be the speed of mouse events, or synchronization between mouse and VBL... In any case, that's extremely weird.

Because Roger said the bug doesn't happen with
16Mhz, triggering it is timing related.

Because Hatari processes host input only on VBL,
IKBD mouse data is injected at specific time in
frame.

I assume that on real HW, IKBD processes mouse
moves completely asynchronously, and EmuTOS
handles the move effects whenever it gets
IKBD interrupt(?) of that.

If true, that means hitting on real HW exactly
the same timing as on Hatari would be quite
unlikely.  With the bug being already otherwise
hard to trigger, well...

Atari and Hatari host mouse movement distances
may also differ, in case the movement distance
has an impact on when the bug appears.


> I guess that adding traces in Hatari Blitter code would help.

"--trace blitter" option provides trace of blitter
register accesses.  they look like this:
blitter write ctrl=80 ctrl_old=00 video_cyc=36936 360@72 pc=e53dea instr_cyc=16 blitter write ctrl=89 ctrl_old=89 video_cyc=37220 136@73 pc=e53df4 instr_cyc=14 blitter write ctrl=81 ctrl_old=81 video_cyc=37508 424@73 pc=e53df4 instr_cyc=14 blitter write ctrl=89 ctrl_old=89 video_cyc=37796 204@74 pc=e53df4 instr_cyc=14 blitter write ctrl=81 ctrl_old=81 video_cyc=38084 492@74 pc=e53df4 instr_cyc=14 blitter write ctrl=80 ctrl_old=00 video_cyc=38136 36@75 pc=e53df4 instr_cyc=14 blitter write ctrl=8c ctrl_old=00 video_cyc=122174 254@240 pc=e512d4 instr_cyc=12 blitter write ctrl=8b ctrl_old=8b video_cyc=122454 26@241 pc=e512dc instr_cyc=14 blitter write ctrl=8b ctrl_old=8b video_cyc=122742 314@241 pc=e512dc instr_cyc=14 blitter write ctrl=8a ctrl_old=8a video_cyc=123030 94@242 pc=e512dc instr_cyc=14 blitter write ctrl=8a ctrl_old=8a video_cyc=123318 382@242 pc=e512dc instr_cyc=14 blitter write ctrl=87 ctrl_old=07 video_cyc=123586 142@243 pc=e512dc instr_cyc=14 blitter write ctrl=8c ctrl_old=07 video_cyc=123788 344@243 pc=e51086 instr_cyc=12


	- Eero



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