On Sun, Jul 25, 2021 at 07:44:11PM +1200, Michael Schmitz wrote: > Am 25.07.2021 um 00:05 schrieb Andreas Schwab: > >On Jul 24 2021, Michael Schmitz wrote: > > > >>According to my understanding, you can't get a F-line exception on > >>68040. > > > >The F-line exception vector is used for all FPU illegal and > >unimplemented insns. > > Thanks - now from my reading of the fpsp040 code (which has mislead me in > the past), it would seem that operations like sin() and exp() ought to raise > that exception then. I don't see that in ARAnyM. Yes, according to the 68040 user's manual, unimplemented and illegal F-line instructions trigger the standard F-line exception vector (11) but have separate stack frame formats so the fpsp040 code gets some extra data. The CPU does a bunch of the prep work so that part doesn't need to be emulated in software. The ARAnyM docs appear to claim a strange combination that wouldn't exist in hardware by implementing a full 68882 instead of the limited subset found on a real 68040. Strangely, that might have been easier to implement. However, it would also completely bypass any use of fpsp040. Brad Boyer flar@xxxxxxxxxxxxx
