Re: [hatari-devel] Fix DSP's rol/ror instructinos

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 02/08/2018 à 12:25, Mariusz Buras a écrit :
> Hi Laurent
> It certainly will fix one part of my upcoming demo :)
>
> Sadly there's a number of other DSP defects in hatari:
> * long interrupts are incorrectly masked. hatari don't seem to adjust 
> IPL level correctly. My case was where I have SSI SEND and RECEIVE 
> interrupts at the same time. On real machine a long interrupt would 
> block SSI interrupts in SR preventing SEND interrputs if RECEIVE was 
> fired. This is obviously only a problem when you forget
> to adjust the SR while developing on hatari and then it doesn't work on 
> Falcon :)
> * It seems that jsset/jsclr can't be used to trigger long interrupt. 
> This seems to work on Falcon. There's no mention of that in the 56001 
> manual though.
>
> SSI seems to be totally out of sync for me. I can share a piece of code 
> which plays sound perfectly fine on falcon while in hatari it sounds 
> really bad.

I can't tell for the other DSP part, laurent is more used to this, but 
for the music not playing good when using dsp, it's a case already known 
for some module players where the 68030 player code send/receive data to 
the dsp without handshake.

Some instructions have a wrong number of cycles in 68030 emulation (due 
to complex prefetch/queuing/caching in the cpu) and in such case it 
means the DSP will not run the correct number of instructions relative 
to how much instructions were done at the same time in the 68030, thus 
creating bad sound.

Unfortunately, this is very complex to fix, as there's no documentation 
for the 68020/30 inner work :(

Nicolas