Re: Bit field usage

From	Joe Pfeiffer <pfeiffer@cs.nmsu.edu>
Newsgroups	comp.lang.c
Subject	Re: Bit field usage
Date	2019-10-27 10:05 -0600
Organization	A noiseless patient Spider
Message-ID	<1bblu29nsl.fsf@pfeifferfamily.net> (permalink)
References	<qorerp$af6$1@dont-email.me> <1bo8y6azlw.fsf@pfeifferfamily.net> <86woctfy1g.fsf@linuxsc.com> <1bwocsalcq.fsf@pfeifferfamily.net> <86o8y2flo5.fsf@linuxsc.com>

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Tim Rentsch <tr.17687@z991.linuxsc.com> writes:

> Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:
>>
>> It was a long time ago...  if I remember correctly (always a big if!)  I
>> was using them to construct things like instruction and floating point
>> formats, and things got scrambled in the switch from Motorola 680x0 to
>> Sparc.
>
> Do you remember anything else?  This tells me when you ran into
> some problems but not what the problems were.  Might the problems
> have been not with bitfields per se but just with platform
> differences?  Making a guess, maybe you simply found it easier to
> get things right (for the two platforms) using shifting and
> masking than using two sets of bitfields?  I think bitfields
> work pretty well for a single platform, but are sometimes hard to
> get right if dealing with multiple platforms.

Oh, the issue was definitely platform differences and portability.  And
yes, I found it immensely easier to get it right for the multiple
platforms with shifts and masks (and macroes defining those shifts and
masks) than bitfields.

I suppose if I'd been confident I was never going to switch platforms
again I might have tried to figure out how to get them to work with the
new platform.  But if I'm remembering correctly that it was the
680x0-Sparc switch, I've changed platforms once (to x86) and arguably
twice (x86-64) since then.

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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