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Re: Bit field usage

From Reinhardt Behm <rbehm@hushmail.com>
Newsgroups comp.lang.c
Subject Re: Bit field usage
Date 2019-10-25 15:46 +0800
Organization A noiseless patient Spider
Message-ID <qou98p$19c$1@dont-email.me> (permalink)
References (5 earlier) <qoss1i$71t$1@news.albasani.net> <vImsF.854893$bv6.259570@fx04.am4> <qot3i5$13b$1@dont-email.me> <87k18tvmng.fsf@bsb.me.uk> <qou7jc$vg9$1@dont-email.me>

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On 10/25/19 3:18 PM, David Brown wrote:
> On 24/10/2019 23:50, Ben Bacarisse wrote:
>> David Brown <david.brown@hesbynett.no> writes:
>>
>>> On 24/10/2019 21:12, Bart wrote:
>> <cut>
>>>> I thought it was generally accepted that bit N of an integer value
>>>> adds 2**N to its value when set. So bit 0 (adding 2**0 or 1) would be
>>>> the least significant.
>>>
>>> It is /generally/ accepted, yes.  But there are exceptions (not here,
>>> though).  In PowerPC (which is primarily big-endian, but some devices
>>> support little-endian mode too) documentation, "bit 0" is the most
>>> significant bit.
>>
>> That numbering is a long-standing IBM tradition.
>>
> 
> I only met it when working with PPC microcontrollers, but I assumed it
> was a tradition that came from the Power processors, following older
> habits from their earliest mainframes.  It certainly has to have
> originated a very long time ago, since (to my knowledge) everyone else
> standardised on "bit x is 2**x" many decades ago.

I remember TI did this too with their 99xx CPUs.

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Thread

Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 08:03 +0200
  Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-24 10:15 -0600
    Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 18:55 +0200
      Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-24 21:28 -0600
    Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-24 17:22 +0000
      Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-24 19:45 +0200
        Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 19:59 +0200
          Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-24 20:02 +0200
            Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-24 21:29 -0600
              Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-25 07:51 +0200
                Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-25 15:05 +0000
        Re: Bit field usage Bart <bc@freeuk.com> - 2019-10-24 19:13 +0100
          Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-24 20:54 +0200
            Re: Bit field usage Bart <bc@freeuk.com> - 2019-10-24 20:12 +0100
              Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-24 23:03 +0200
                Re: Bit field usage Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 22:50 +0100
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-25 09:18 +0200
                Re: Bit field usage Reinhardt Behm <rbehm@hushmail.com> - 2019-10-25 15:46 +0800
                Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:36 -0500
                Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-25 15:04 +0000
                Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:40 -0500
                Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 21:12 +0200
              Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-25 09:25 -0600
                Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:52 -0500
      Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 19:56 +0200
        Re: Bit field usage already5chosen@yahoo.com - 2019-10-24 12:03 -0700
          Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-24 19:40 +0000
            Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 22:15 +0200
            Re: Bit field usage already5chosen@yahoo.com - 2019-10-24 14:16 -0700
    Re: Bit field usage Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-10-24 17:50 -0700
      Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-25 09:36 -0600
        Re: Bit field usage Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-10-27 04:54 -0700
          Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-27 10:05 -0600
  Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 20:15 +0200
    Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 20:16 +0200
      Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-26 20:37 +0200
        Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 13:41 -0500
          Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-26 21:54 +0200
            Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 03:46 -0700
              Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-27 12:50 +0100
                Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 06:37 -0700
              Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-27 13:00 +0100
                Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 07:19 -0700
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-27 22:30 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-07 12:36 -0800
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-08 08:18 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-08 10:19 -0800
                Re: Bit field usage Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-11-08 21:47 +0000
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-10 14:08 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-11 09:26 -0800
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-11 20:31 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-11 23:01 -0800
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-11 23:25 -0800
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-12 10:54 +0100
                Re: Bit field usage Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-11-12 14:43 +0000
                Re: Bit field usage James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-12 10:54 -0500
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-12 19:37 +0100
              Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-27 08:36 -0500
                Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 06:49 -0700
            Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-27 14:23 +0100
            Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-27 08:42 -0500
        Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 21:06 +0200
        Re: Bit field usage Bart <bc@freeuk.com> - 2019-10-26 20:41 +0100
          Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-27 08:29 +0100
            Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-27 13:05 +0100

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