Re: What happened to short float?

Subject	Re: What happened to short float?
Newsgroups	comp.lang.c
References	<p3nt6t$uid$1@solani.org> <p3o61s$66s$1@dont-email.me> <p3q3am$cd4$1@solani.org>
From	bartc <bc@freeuk.com>
Message-ID	<8B08C.431211$eO2.190050@fx34.am4> (permalink)
Organization	virginmedia.com
Date	2018-01-18 12:40 +0000

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On 18/01/2018 12:18, Philipp Klaus Krause wrote:
> Am 17.01.2018 um 19:52 schrieb jacobnavia:
>> Le 17/01/2018 à 17:21, Philipp Klaus Krause a écrit :
>>> At the 2016 London meeting of WG14, adding a new short float type
>>> (N2016) was discussed, and there was a clear consensus to move forward.
>>>
>>> What has happened about short float since?
>>>
>>> Philipp
>>>
>> lcc hasn't implemented them because of time constraints.
>>
>> They are a memory only format. The x86 transforms them on floats on
>> reading them from RAM. The same for ARM.
>>
>> They reduce the size of the data at the expense of precision. For many
>> applications that can be a bonus, it depends.
>>
> 
> I'm somewhat interested in them, since their implementation could be
> cosiderably faster than float/double on machines without hardware
> support for floating-point operations. Typical examples would be most
> 8-bit µCs.

If the 8-bit machine has some 16-bit support, then 24-bit is another 
option, which gives more precision and range (somewhat better than the 
4-figure log tables I used at school actually).

That would be 8-bit sign/exponent and 16-bit mantissa, which can be 
accessed more tidily. There can't be an extra implied bit unless it can 
be done without requiring 17-bit arithmetic.

I understand the official 16-bit format uses a 10-bit mantissa (11 in 
total) so some 16-bit calculations are needed anyway.

-- 
bartc

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What happened to short float? Philipp Klaus Krause <pkk@spth.de> - 2018-01-17 17:21 +0100
  Re: What happened to short float? "James R. Kuyper" <jameskuyper@verizon.net> - 2018-01-17 11:42 -0500
    Re: What happened to short float? jacobnavia <jacob@jacob.remcomp.fr> - 2018-02-02 23:08 +0100
      Re: What happened to short float? Jakob Bohm <jb-usenet@wisemo.com> - 2018-02-05 07:57 +0100
        Re: What happened to short float? jameskuyper@verizon.net - 2018-02-05 05:31 -0800
      Re: What happened to short float? Tim Prince <tprince@intelretiree.com> - 2018-02-05 08:55 -0500
        Re: What happened to short float? jacobnavia <jacob@jacob.remcomp.fr> - 2018-02-05 15:46 +0100
        Re: What happened to short float? GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-02-08 01:29 +0100
          Re: What happened to short float? Keith Thompson <kst-u@mib.org> - 2018-02-07 16:59 -0800
            Re: What happened to short float? Philipp Klaus Krause <pkk@spth.de> - 2018-02-08 09:08 +0100
              Re: What happened to short float? Keith Thompson <kst-u@mib.org> - 2018-02-08 09:27 -0800
            Re: What happened to short float? GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-02-08 09:54 +0100
              Re: What happened to short float? Keith Thompson <kst-u@mib.org> - 2018-02-08 10:13 -0800
            Re: What happened to short float? jameskuyper@verizon.net - 2018-02-08 06:36 -0800
              Re: What happened to short float? GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-02-08 17:04 +0100
                Re: What happened to short float? jameskuyper@verizon.net - 2018-02-08 08:56 -0800
                Re: What happened to short float? scott@slp53.sl.home (Scott Lurndal) - 2018-02-08 17:23 +0000
                Re: What happened to short float? GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-02-08 18:52 +0100
                Re: What happened to short float? jameskuyper@verizon.net - 2018-02-08 11:27 -0800
                Re: What happened to short float? GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-02-08 22:58 +0100
              Re: What happened to short float? Keith Thompson <kst-u@mib.org> - 2018-02-08 10:18 -0800
          Re: What happened to short float? Jakob Bohm <jb-usenet@wisemo.com> - 2018-02-08 18:59 +0100
            Re: What happened to short float? Robert Wessel <robertwessel2@yahoo.com> - 2018-02-08 16:22 -0600
              Re: What happened to short float? Jakob Bohm <jb-usenet@wisemo.com> - 2018-02-09 15:01 +0100
  Re: What happened to short float? Chad <cdalten@gmail.com> - 2018-01-17 09:12 -0800
  Re: What happened to short float? scott@slp53.sl.home (Scott Lurndal) - 2018-01-17 17:31 +0000
  Re: What happened to short float? jacobnavia <jacob@jacob.remcomp.fr> - 2018-01-17 19:52 +0100
    Re: What happened to short float? Philipp Klaus Krause <pkk@spth.de> - 2018-01-18 13:18 +0100
      Re: What happened to short float? bartc <bc@freeuk.com> - 2018-01-18 12:40 +0000

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