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Re: [Qemu-devel] [PATCH v2 3/3] target-m68k: add cas/cas2 ops


From: Richard Henderson
Subject: Re: [Qemu-devel] [PATCH v2 3/3] target-m68k: add cas/cas2 ops
Date: Thu, 3 Nov 2016 13:20:02 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0

On 11/03/2016 12:03 PM, Laurent Vivier wrote:
CC_OP_CMPW for cas2w.

It was working because I have used helper_be_ldsw_mmu() to load values,
is it better to use helper_be_lduw_mmu with CC_OP_CMPW?

IIRC, one needs the extra sign-extension here:

    case CC_OP_CMPB:                                                       \
    case CC_OP_CMPW:                                                       \
    case CC_OP_CMPL:                                                       \
        src1 = n;                                                          \
        src2 = v;                                                          \
        res = EXTSIGN(src1 - src2, op - CC_OP_CMPB);                       \

to get all of the flags correct, even though just Z would be correct without.


r~



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