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Re: [Qemu-devel] [PATCH for-2.5 02/30] m68k: manage scaled index


From: Richard Henderson
Subject: Re: [Qemu-devel] [PATCH for-2.5 02/30] m68k: manage scaled index
Date: Tue, 11 Aug 2015 20:42:44 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0

On 08/09/2015 01:13 PM, Laurent Vivier wrote:
Scaled index is not supported by 68000, 68008, and 68010.

     EA = (bd + PC) + Xn.SIZE*SCALE + od

Ignore it:

M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
2.4 BRIEF EXTENSION WORD FORMAT COMPATIBILITY

"If the MC68000 were to execute an instruction that
  encoded a scaling factor, the scaling factor would be
  ignored and would not access the desired memory address.
  The earlier microprocessors do not recognize the brief
  extension word formats implemented by newer processors.
  Although they can detect illegal instructions, they do not
  decode invalid encodings of the brief extension word formats
  as exceptions."

Signed-off-by: Laurent Vivier<address@hidden>
---
  target-m68k/translate.c | 5 +++++
  1 file changed, 5 insertions(+)

Reviewed-by: Richard Henderson <address@hidden>


r~



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