Re: [hatari-devel] Special WinUAE FPU settings

[ Thread Index | Date Index | More Archives ]

>> Seems like there is a similar setting for the FPU, too:
>>   fpu_no_unimplemented
>> ... should we also initialize that to "true"?
> hi,
> I would say yes if we want to be close to real HW ; this affects a few
> instruction, but I don't know the different fpu specs that much, maybe
> Toni can give us detail if he read this.

If it is true, 68040/060 FPU emulation matches real hardware: 68040 FPU
instructions that are not implemented in hardware (trigonometric
functions, some FMOVEM variants etc..) cause unimplemented FPU
exceptions (that Motorola FPU library normally catches and emulates)

If it is false, all FPU instructions are emulated, all 6888x
instructions + new 68040 FPU FSx and FDx variants. (Note that some older
versions in 6888x mode also incorrectly supported 68040+ only FPU

cpu_no_implemented is matching option for 68060 unimplemented integer
instructions (MOVEP, some 64-bit variants of MUL/DIV etc).

It is recent option, 68040/060 missing instruction exception emulation
was not easy to implement.

Note that they are not fully JIT compatible. IMHO there is not much
point anyway in fast modes where it is only important that FPU returns
correct results, not how it does it.

(What did this have to do with 68030 MMU PMOVE?)

Mail converted by MHonArc 2.6.19+