Re: [hatari-devel] Hatari profiler updates and CPU cycle questions

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 30/01/2013 16:45, Eero Tamminen a écrit :
> Hi,
>
> I've put the first version of Hatari profiler post-processor to Mercurial.
>
> It can be used like explained here:
> http://sourceforge.net/mailarchive/forum.php?thread_name=201301301616..27316.oak%40helsinkinet.fi&forum_name=emutos-
> devel
>
> I noticed that CPU cycle counter returns cumulative values so I compensated
> for that, and for the cycle value being for a previous instruction [1].
>
> Now I'd like to know, is it possible for an instruction to use 0 cycles,
> like CPU cycle counter value difference would indicate for subq here:

Hello,

no that's not possible (except for "stop" which is particular as the cpu 
goes idle until an interrupt happens), unless some kind of parallelism 
is taking place.
Here, subq should be 4 cycles I guess.

> ------------------------------------------
> [...]
> $e0247e :  cmp.w     $ff88(a6),d0     0.00% (26, 104, 0)
> $e02482 :  bgt       $e02586          0.00% (26, 52, 0)
> $e02486 :  add.w     $ff96(a6),d0     0.00% (26, 104, 0)
> $e0248a :  subq.w    #1,d0            0.00% (26, 0, 0)
> $e0248c :  cmp.w     $ff88(a6),d0     0.00% (26, 104, 26)
> $e02490 :  ble.s     $e0249a          0.00% (26, 52, 26)
> [...]
> ------------------------------------------
> ?
>
> Also, what is the largest cycle count that a single m68k instruction
> can have?

depend on the 680xx variant. For 68000, movem.l or div should be the 
largest instruction.

Nicolas