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b6d45608
@REPLYADDR Terje Mathisen
<terje.mathisen@tmsw.no>
@REPLYTO 2:5075/128 Terje Mathisen
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Anton Ertl wrote:
> John Levine <
johnl@taugh.com> writes:
>> But on z/Series they do indeed have packed decimal vector instructions
>> using the 128 bit vector registers as 31 digits and a sign. There is
>> also decimal floating point
>
> Decimal floating-point hardware seems to be a marketing feature to me.
> Is there any real-world application that uses that? How much CPU-time
> does it use? Intel has neglected its DFP implementation (in
> software), which indicates that any such applications, if they exist,
> are insignificant.
>
> As for packed BCD stuff, I expect that the Cobol stuff benefits from
> that. But given that the byte-by-byte instructions were good enough
> in earlier times with slower CPUs, do we need faster instructions for
> that now. Have the amounts of data processed by these programs
> increased so much?
Both Ascii and Nybble math can be done quite easily with SIMD vector
ops, giving an order of magntude better throughput than using the
single-digit instructions.
Terje
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