Re: [hatari-devel] Many changes to MFP

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

On 14/03/2013 09:46, Eero Tamminen wrote:

> I'm counting the time as: <spent cycles> / MachineClocks.CPU_Freq.
>
> Spent cycles are counted with:
>          if (bDspEnabled) {
>                  cycles = Cycles_GetCounter(CYCLES_COUNTER_CPU);
>          } else {
>                  Uint32 newcycles = Cycles_GetCounter(CYCLES_COUNTER_CPU);
>                  cycles = newcycles - cpu_profile.prev_cycles;
>                  cpu_profile.prev_cycles = newcycles;
>          }
>
>
> Any idea why that could be so wrong for TT emulation?

For now, MachineClocks.CPU_Freq is not really used, it's just 
informative. You also need to check if cpu freq is 8,16 or 32 (using the 
>> operator to divide cycles by 2 or 4). No clean solution for now, it 
can be solved latter as it doesn't impact emulation itself. Add a 
special case for the TT if you need in your code.

> 	- Eero
>
> PS. why the cycles counters are ints, instead of unsigned?

Because those counter (as they're used today) will never reach the max 
of an int, they're usually reset before :)
 That's historical, I think anyway they should be dropped at some point 
and use CyclesGlobalClockCounter instead.

Nicolas