| Re: [hatari-devel] Small bug in Hatari Falcon emulation |
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On 25 Nov 2020 at 2:34, Eero Tamminen wrote:
>
> Hopefully this pseudo-code (without bus error
> checking) clarifies what I meant:
> -------------------------------------
> for (addr = start; addr < end; addr++) {
> old = value;
> value = *addr;
> /* this check is what I'm referring to: */
> if (value == old) {
> value = ^value;
> old = value;
> value = *addr;
> if (value == old) {
> printf("0x%06x = <no value>\n", addr);
> continue;
> }
> }
> printf("0x%06x = 0x02x\n", addr, value);
> }
> -------------------------------------
>
>
> > I did write a separate program to do:
> > read
> > write new/read
> > write old/read
> > and the value returned isn't always $ff (and rewriting the original value
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > doesn't restore it, unsurprising considering there's no RAM there). I
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> think
> > it's just floating bus values, but I'm not a hardware guy.
> >
> >> You seemed to be doing byte reads. For IO HW
> >> regs, it matters whether read is byte or word
> >> sized. Did you try word access?
> >>
> > 1. As I said in my original post, the report is NOT about accessing the
> I/O
> > memory area. Hatari already has some code to handle that & I haven't
> > investigated whether that code is correct or not. The report is strictly
> about
> > accessing the RAM area, both existing & non-existing memory.
>
> You said that value is 0xff, which I assume to
> be from a byte read. If you do word reads from
> non-existing RAM area, is the value 0xffff (as
> expected), or something else?
>
>
> > 2. I spent some more of my time and added support for different widths of
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > memory access. Unsurprisingly (to me) the same issue happens with
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > byte/word/long widths.
^^^^^^^^^^^^^^^^^^^^^^^^^^
> >
Did you read my 2nd message (quoted above)? See the underlined bits.
> > If you want any more answers, I'll send you the code & you can investigate
> > further.
>
> Unfortunately I don't have Falcon HW.
>
If you write a program to get the data you want, I'll run it on my Falcon.
Roger