Re: [hatari-devel] New version of WinUAE's cpu core

The first region clears $fffffa01, 03, 05, 07, 09, b, d, f, 11, 13, 15, 17 - without touching the even addresses. It's a nice and proper usage of the movep instruction. Achieving the same using the same amount of code space (18 bytes, makes for simple patching) is doable. Suggestion:

lea $fffffa01.w,a0

moveq #11,d0

loop clr.b (a0)

lea 2(a0),a0

dbf d0,loop

nop

(The last nop is a space filler, this code is actually smaller than the original)

In hex:

41f8 fa01

700b 4210

41e8 0002

51c8 fff8

4e71

The second region is trickier due to space limitations. It sets $fffffa27 to $00, 29 to $88, 2b to $01 and 2d to $05 using only 7 bytes of code. A naïve clr.b/move.b replacement is 12 bytes. I'll ponder it over lunch.

/Troed

On Mon, Nov 24, 2014 at 11:44 AM, Thomas Huth <th.huth@xxxxxx> wrote:

Am Mon, 24 Nov 2014 10:41:03 +0100
schrieb Nicolas Pomarède <npomarede@xxxxxxxxxxxx>:

> Le 24/11/2014 08:47, Thomas Huth a écrit :
>
> > FYI, as a quick hack, I've patched the movep instructions that occur
> > during the boot process to nops:
> >
> > static const TOS_PATCH TosPatches[] =
> > {
> > ...
> > { 0x404, -1, "060fix", TP_ALWAYS, 0xE025E2, 0x01C80000, 12,
> > pNopOpcodes }, { 0x404, -1, "060fix", TP_ALWAYS, 0xE0263C,
> > 0x01C80026, 4, pNopOpcodes }, ...
> > };
> >
> > Then the desktop is successfully reached again also in 68060 mode..
> > So it's not that much that has to be fixed in TOS.
> >
>
> hi
>
> does it mean those movep were useless ? Shouldn't they be replaced by
> 2 move.b for example ?

First region seems to pre-initialize the MFP:

$e025dc : 41f8 fa01 lea $fffffa01.w,a0
$e025e0 : 7000 moveq #0,d0
$e025e2 : 01c8 0000 movep.l d0,0(a0)
$e025e6 : 01c8 0008 movep.l d0,8(a0)
$e025ea : 01c8 0010 movep.l d0,$10(a0)
$e025ee : 117c 0048 0016 move.b #$48,$16(a0)
$e025f4 : 08e8 0002 0002 bset #2,2(a0)

The second region is setting some more values there:

$e02632 : 41f8 fa01 lea $fffffa01.w,a0
$e02636 : 203c 0088 0105 move.l #$880105,d0
$e0263c : 01c8 0026 movep.l d0,$26(a0)

So it likely works in Hatari to nop them out because the MFP is in a
sane state at the beginning, but that's certainly not a proper fix and
should be replaced with correct code for setting up the MFP instead.

Thomas