Re: [hatari-devel] Getting cycles used by previous or next instruction without modifying CPU state?

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

On 20/02/2012 23:50, Eero Tamminen wrote:
> Hi,
>
> How do I get how many cycles previous instruction used, for
> profiling purposes?
>
> src/debug/profile.c has this code:
>          Uint32 opcode, cycles;
>          opcode = get_iword_prefetch (0);
>          cycles = (*cpufunctbl[opcode])(opcode) + nWaitStateCycles;
>
> But that's bad, calling the opcode table function modifies
> the CPU state.

Hello

I don't think you can get this easily. Only the current instruction 
cycles are available.
Always saving current cycles in previous cycles before executing a new 
opcode would be too costy.

If that's just for test purpose, you can add some kind of breakpoint 
that would trigger on every instruction and then save the current cycles 
in your own variable. But this would certainly slow down emulation a lot.

Nicolas