Re: [hatari-devel] 68030 cycle timings for 64bit div/mul

[laurent.sallafranque@xxxxxxx]

Hi,

Motorola doc gives a max value in the docs for the mul and div instructions (for every declinaison of these instruction, ie .w, .l, 64 bits, and for the signed/unsigned instructions).

I've inplemented these max values into hatari, but of course, this is not accurate.
As long as we don't manage to figure how motorola implemented these instr into the CPU, 68030 emu won't be accurate here.

Regards

Laurent


----- Mail original -----
De: "Douglas Little" <doug694@xxxxxxxxxxxxxx>
À: "Nicolas Pomarède" <npomarede@xxxxxxxxxxxx>
Cc: hatari-devel@xxxxxxxxxxxxxxxxxxx
Envoyé: Mardi 29 Janvier 2013 17:05:46
Objet: Re: [hatari-devel] 68030 cycle timings for 64bit div/mul

Hi Nicolas, 




it's not handled. 64 bit mul/div are more complex than the 68000 equivalent and so far no one has reverse engineered those instructions to "guess" the algorithm and its timing. 




Ok I see. So what is the expected behaviour for a program using these instructions in Hatari? 


BadMood uses these instructions and I have not studied any diverse effects from using them (timing, accuracy, invalid results....). It just appeared to work.... 


Thanks, 
D.