Re: FPU emulation incorrect for 68LC040?

Mattias Engdegård
2010-07-21T21:27:30Z

21 jul 2010 kl. 22.32 skrev Geert Uytterhoeven:

> As the 'LC040 doesn't implement FPU instructions, I'd expect it to
> just generate an
> exception when the "fadd.d (a0)+,fp0" is encountered. I.e. not do
> anything else,
> like postincrementing a0.

According to the manual, it generates a special 8-word exception frame
that contains the decoded effective address, as a help to the
emulator. It only makes sense if the user can just use that EA right
away (after having established that it is a memory operand). I suppose
the only way to find out is to find someone with a genuine 'LC040 (a
non-buggy one).