qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 04/52] target-m68k: manage scaled index


From: Richard Henderson
Subject: Re: [Qemu-devel] [PATCH 04/52] target-m68k: manage scaled index
Date: Fri, 6 May 2016 06:36:20 -1000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.0

On 05/04/2016 10:11 AM, 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~





reply via email to

[Prev in Thread] Current Thread [Next in Thread]