Re: Cost of handling misaligned access

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Sujet : Re: Cost of handling misaligned access
De : mitchalsup (at) *nospam* aol.com (MitchAlsup1)
Groupes : comp.arch
Date : 18. Feb 2025, 23:33:41
Autres entêtes
Organisation : Rocksolid Light
Message-ID : <a34ce3b43fab761d13b2432f9e255fab@www.novabbs.org>
References : 1 2 3 4 5 6 7 8 9 10 11
User-Agent : Rocksolid Light
On Tue, 18 Feb 2025 21:09:54 +0000, Terje Mathisen wrote:

MitchAlsup1 wrote:
On Tue, 18 Feb 2025 13:07:39 +0000, Michael S wrote:
>
On Tue, 18 Feb 2025 02:55:33 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:
>
It takes Round Nearest Odd to perform Kahan-Babashuka Summation.
>
>
Are you aware of any widespread hardware that supplies Round to Nearest
with tie broken to Odd? Or of any widespread language that can request
such rounding mode?
>
No, No
>
Until both, implementing RNO on niche HW looks to me as wastage of both
HW resources and of space in your datasheet.
>
They way I implement it, it is only an additional 10± gates.
>
With discrete logic, it should be identical to RNE, except for flipping
the ulp bit when deciding upon the rounding direction, right?
Yes,

With a full 4-bit lookup table you need a few more gates, but that is
still the obvious way to implement rounding in SW. (It is only ceil()
and floor() that requires the sign bit as input, the remaining rounding
modes can make do with ulp+guard+sticky.
sign+ULP+Gard+sticky is all you ever need for any rounding mode
IEEE or beyond.

Terje

Date Sujet#  Auteur
13 Feb 25 * Re: Cost of handling misaligned access48Marcus
13 Feb 25 +- Re: Cost of handling misaligned access1Thomas Koenig
14 Feb 25 +* Re: Cost of handling misaligned access41BGB
14 Feb 25 i`* Re: Cost of handling misaligned access40MitchAlsup1
18 Feb 25 i `* Re: Cost of handling misaligned access39BGB
18 Feb 25 i  +* Re: Cost of handling misaligned access33MitchAlsup1
18 Feb 25 i  i+- Re: Cost of handling misaligned access1BGB
18 Feb 25 i  i`* Re: Cost of handling misaligned access31Michael S
18 Feb 25 i  i +- Re: Cost of handling misaligned access1Thomas Koenig
18 Feb 25 i  i +* Re: Cost of handling misaligned access26MitchAlsup1
18 Feb 25 i  i i`* Re: Cost of handling misaligned access25Terje Mathisen
18 Feb 25 i  i i `* Re: Cost of handling misaligned access24MitchAlsup1
19 Feb 25 i  i i  `* Re: Cost of handling misaligned access23Terje Mathisen
19 Feb 25 i  i i   `* Re: Cost of handling misaligned access22MitchAlsup1
19 Feb 25 i  i i    `* Re: Cost of handling misaligned access21BGB
20 Feb 25 i  i i     +- Re: Cost of handling misaligned access1Robert Finch
20 Feb 25 i  i i     +* Re: Cost of handling misaligned access5MitchAlsup1
20 Feb 25 i  i i     i+* Re: Cost of handling misaligned access2BGB
20 Feb 25 i  i i     ii`- Re: Cost of handling misaligned access1BGB
21 Feb 25 i  i i     i`* Re: Cost of handling misaligned access2Robert Finch
21 Feb 25 i  i i     i `- Re: Cost of handling misaligned access1BGB
21 Feb 25 i  i i     `* Re: Cost of handling misaligned access14BGB
22 Feb 25 i  i i      +- Re: Cost of handling misaligned access1Robert Finch
22 Feb 25 i  i i      `* Re: Cost of handling misaligned access12Robert Finch
23 Feb 25 i  i i       +* Re: Cost of handling misaligned access10BGB
23 Feb 25 i  i i       i`* Re: Cost of handling misaligned access9Michael S
24 Feb 25 i  i i       i +- Re: Cost of handling misaligned access1BGB
24 Feb 25 i  i i       i `* Re: Cost of handling misaligned access7Michael S
24 Feb 25 i  i i       i  +* Re: Cost of handling misaligned access4Robert Finch
24 Feb 25 i  i i       i  i+- Re: Cost of handling misaligned access1BGB
24 Feb 25 i  i i       i  i`* Re: Cost of handling misaligned access2MitchAlsup1
25 Feb 25 i  i i       i  i `- Re: Cost of handling misaligned access1BGB
25 Feb 25 i  i i       i  `* Re: Cost of handling misaligned access2MitchAlsup1
25 Feb 25 i  i i       i   `- Re: Cost of handling misaligned access1BGB
23 Feb 25 i  i i       `- Re: Cost of handling misaligned access1Robert Finch
18 Feb 25 i  i `* Re: Cost of handling misaligned access3BGB
19 Feb 25 i  i  `* Re: Cost of handling misaligned access2MitchAlsup1
19 Feb 25 i  i   `- Re: Cost of handling misaligned access1BGB
18 Feb 25 i  `* Re: Cost of handling misaligned access5Robert Finch
18 Feb 25 i   `* Re: Cost of handling misaligned access4BGB
18 Feb 25 i    `* Re: Cost of handling misaligned access3Brett
18 Feb 25 i     `* Re: Cost of handling misaligned access2Marcus
18 Feb 25 i      `- Re: Cost of handling misaligned access1BGB
17 Feb 25 `* Re: Cost of handling misaligned access5Terje Mathisen
17 Feb 25  +- Re: Cost of handling misaligned access1Thomas Koenig
17 Feb 25  `* Re: Cost of handling misaligned access3MitchAlsup1
17 Feb 25   `* Re: Cost of handling misaligned access2Terje Mathisen
17 Feb 25    `- Re: Cost of handling misaligned access1MitchAlsup1

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