basilisk-devel

[B2-devel] MOVE16 (Ax)+,(Ay)+

[Lauri P. <lpe...@ni...>]

Hello,

One of the Motorola errata files ("040de.txt" in my Motorola
archive, "DOCUMENTATION CLARIFICATION FOR MC68040, MC68EC040 &
MC68LC040") states:

"MOVE16 (Ax)+,(Ay)+ where Ax=Ay is functionally the same as
 MOVE16 (Ax),(Ay)+.  The address register only gets incremented
 once and the line is copied over itself instead of copied into
 the next line."

So in op op_f620_0(), instead of:
 m68k_areg(regs, srcreg) += 16;\r\n");
 m68k_areg(regs, dstreg) += 16;\r\n");

we should probably do:
 if(srcreg != dstreg) m68k_areg(regs, srcreg) += 16;\r\n");
 m68k_areg(regs, dstreg) += 16;\r\n");

I know that this is a degenerate case, but Murphy's Law states
that some weird program relies on this particular behavior :)

Lauri

Re: [B2-devel] MOVE16 (Ax)+,(Ay)+

[Christian B. <cb...@st...>]

Hi!

On Tue, Sep 05, 2000 at 09:46:07PM +0300, Lauri Pesonen wrote:
> we should probably do:
>  if(srcreg != dstreg) m68k_areg(regs, srcreg) += 16;\r\n");
>  m68k_areg(regs, dstreg) += 16;\r\n");

Ok.

Bye,
Christian

-- 
  / Coding on PowerPC and proud of it
\/ http://www.uni-mainz.de/~bauec002/

Re: [B2-devel] MOVE16 (Ax)+,(Ay)+

[<gb...@di...>]

Hi,

> we should probably do:
>  if(srcreg != dstreg) m68k_areg(regs, srcreg) += 16;\r\n");
>  m68k_areg(regs, dstreg) += 16;\r\n");

OK, I added your patch plus other MOVE16 instructions in the table68k.
For that purpose, I added "Al" meaning absolute long. I also enhanced
the table68k for better (I hope) flag usage information and control flow
information (an extra field).

Some optimizations can still be made for MOVE16 instructions by using
do_put/do_get mem functions instead of put/get functions and thus
avoiding the double byteswapping of the data. But as we are not in a
critical point yet, I left those as is ;-)

The MOVE16 instructions in the new table68k look like:
1111 0110 0010 0rrr:40:-----:-----:--:12: MOVE16   ArP,ARP
1111 0110 00ss sSSS:40:-----:-----:--:12: MOVE16   s[Dreg-Aipi],Al
1111 0110 00dd dDDD:40:-----:-----:--:12: MOVE16   Al,d[Areg-Aipi]
1111 0110 00ss sSSS:40:-----:-----:--:12: MOVE16   s[Aind],Al
1111 0110 00dd dDDD:40:-----:-----:--:12: MOVE16   Al,d[Aipi-Aind]

% EmulOp instructions
0111 0001 0000 0000:00:-----:-----:-R:00: EMULOP_RETURN
0111 0001 EEEE EEEE:00:-----:-----:--:10: EMULOP   #E

Since, I also temporarily disabled ARM, M68K, SPARC optimizations, I
won't commit before tommorrow night. I deactivated those because
optimized flag handling are now used under a common interface. i.e.
optflag_test_*, optflag_add_*, as in the latest UAE sources.

Bye.
-- 
Gwenolé Beauchesne