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From: David Hildenbrand <david@redhat.com>
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Date: Tue, 16 Apr 2019 11:10:30 +0200
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Subject: Re: [Qemu-devel] [PATCH v1 15/41] s390x/tcg: Implement VECTOR
 GALOIS FIELD MULTIPLY SUM (AND ACCUMULATE)
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To: Richard Henderson <richard.henderson@linaro.org>, qemu-devel@nongnu.org
Cc: qemu-s390x@nongnu.org, Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>, Richard Henderson <rth@twiddle.net>

On 13.04.19 01:44, Richard Henderson wrote:
> On 4/11/19 12:08 AM, David Hildenbrand wrote:
>> A galois field multiplication in field 2 is like binary multiplication,
>> however instead of doing ordinary binary additions, xor's are performed.
>> So no carries are considered.
>>
>> Implement all variants via helpers. s390_vec_sar() and s390_vec_shr()
>> will be reused later on.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  target/s390x/helper.h           |   8 ++
>>  target/s390x/insn-data.def      |   4 +
>>  target/s390x/translate_vx.inc.c |  38 ++++++++
>>  target/s390x/vec_int_helper.c   | 168 ++++++++++++++++++++++++++++++++
>>  4 files changed, 218 insertions(+)
> 
> FYI, this is now the 4th copy of this operation.
> 
>   arm: pmull
>   x86: pclmulqdq
>   ppc: vpmsum[bhwd]
> 
> We really should promote this to generic.  But that can come later,

huh, I tried my best to search for anything related to galois, but seems
like only s390x uses that terminology.  :) Well at least I learned how
it is supposed to be calculated.

Thanks!

> 
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> 
> 
> r~
> 


-- 

Thanks,

David / dhildenb