Re: [hatari-devel] Movem and cycles

[Toni Wilen <twilen@xxxxxxxxxx>]

> Hi
> 
> for now, only 68030 in CE will count cycles for instructions with non
> fixed cycles count.
> 
> Toni, do you think it would be possible to extend gencpu and to define
> "using_simple_cycles = 1" for cpu id 20 and 22, maybe 32 too ? (as it's
> the case for id 12 and 68000 in prefetch mode).
> 
> It could give some extra accuracy when CE mode is not needed for movem,
> bit shift, muls/divs
> 
> Just adding "using_simple_cycles = 1;" is not enough at the moment
> because in that case gencpu checks for "using_prefetch" and not for
> "using_prefetch_020", but maybe adding this would be not to invasive ?

I don't think it helps. MOVEM depends on memory access speed, it is not
CPU core's problem to time it ("memory cycle exact mode" should do that,
which only counts external memory access cycles, CPU internal cycles are
instant), shift cycle usage is static in 68020+ (it has barrel shifter).
And finally, no one knows how mul or div work in 68020+.