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Groups > comp.lang.c > #98486

Re: micro-architectural details

From BartC <bc@freeuk.com>
Newsgroups comp.lang.c
Subject Re: micro-architectural details
Date 2016-12-09 12:12 +0000
Organization A noiseless patient Spider
Message-ID <o2e71s$bg3$1@dont-email.me> (permalink)
References (10 earlier) <o2cl1i$8c8$1@dont-email.me> <o2cmht$dkt$1@dont-email.me> <fe3c6276-4f04-465d-98da-9c127ddb9937@googlegroups.com> <o2coie$jpb$1@dont-email.me> <eavj87F7ao8U1@mid.uni-berlin.de>

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On 09/12/2016 11:35, Jens Thoms Toerring wrote:
> Noob <root@127.0.0.1> wrote:
>> On 08/12/2016 23:34, supercat@casperkitty.com wrote:
>
>>> On Thursday, December 8, 2016 at 4:25:24 PM UTC-6, Noob wrote:
>>>> "A proposal to add binary constants was rejected due to lack of
>>>> precedent and insufficient utility."
>>>>
>>>> Perhaps after a few decades of gcc, clang, and icc having that
>>>> particular extension, WG14 will accept it?
>>>
>>> Not to mention a huge variety of embedded compilers.  Statements like the
>>> above make me wonder if anyone on the Committee does anything with embedded
>>> or systems programming.
>
>> In Linux, it seems arch/arm64/kvm uses a few binary constants,
>> but I don't see other uses. Either programmers don't find them
>> useful enough, or they've grown used to not having them.
>
> I've seen them supported by some embedded compilers but just
> find them annoying. It's much harder to find bit 23 in a string
> of 32 '0' and '1' than by looking at a hex constant and doing
> the tiniest bit of mental arithmetic. Or try comparing two of
> them visually when they aren't nicely lined up, one over the
> other. So to me the "insufficient utility" argument seems not
> too far off the mark;-)

It's a rubbish implementation then. Try:

  2x0000_0100__1001_0110__0000_1111__1101_1000

They are grouped in blocks of 8 as bits 31..24, 23..16, 15..8 and 7..0. 
I've also split each block into two so that each four bits corresponds 
to the hex.

Try this however in hex, where groups of 5 bits are significant:

2x00110_01001_10000_11001

Or this where you want alternating groups of 0s and 1s, the width of 
each group increasing by one bit each time (I used stuff like this for 
defining dotted line patterns in graphics drivers):

   2x11111111_0000000_111111_00000_1111_000_11_0

Intel datasheets for devices such as 8086 used to represent instruction 
codings in binary where specific groups were significant:

   2x_01_011_101

This now matches exactly what might be in the datasheet instead of using 
hex or (more usefully) octal.

Or suppose you're comparing these two values trying to see some 
similarity or some link:

  2x11010010          // D2
  2x01101001          // 69

You'd have to be pretty good at hex to see that they are the same 
pattern but with a 1-bit shift (0xD2 is 0x69*2).

[I think gcc uses 0b rather than 2x as the prefix; but it doesn't have 
separators.]

-- 
Bartc

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"Let’s Stop Bashing C" Lynn McGuire <lynnmcguire5@gmail.com> - 2016-12-05 19:57 -0600
  Re: "Let’s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-06 02:34 +0000
    Re: "Let’s Stop Bashing C" BGB <cr88192@hotmail.com> - 2016-12-06 00:13 -0600
      Re: "Let’s Stop Bashing C" BartC <bc@freeuk.com> - 2016-12-06 23:15 +0000
        Re: "Let’s Stop Bashing C" BGB <cr88192@hotmail.com> - 2016-12-06 21:16 -0600
    Re: "Let’s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-06 11:54 +0000
    Re: "Let’s Stop Bashing C" BartC <bc@freeuk.com> - 2016-12-06 12:07 +0000
      Re: "Let’s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-06 12:25 +0000
        Re: "Let’s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-06 14:07 +0100
          Re: "Let’s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-06 13:40 +0000
        Re: "Let’s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-06 19:40 +0100
          Re: "Lete2��s Stop Bashing C" Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-06 13:55 -0500
            Re: "Lete2��s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-06 19:13 +0000
              Re: "Lete2��s Stop Bashing C" Keith Thompson <kst-u@mib.org> - 2016-12-06 11:51 -0800
                Re: "Lete2��s Stop Bashing C" supercat@casperkitty.com - 2016-12-06 12:22 -0800
            Re: "Lete2��s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-06 20:16 +0100
            Re: "Lete2�™s Stop Bashing C" supercat@casperkitty.com - 2016-12-06 11:20 -0800
              Re: "Lete2�™s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-06 22:15 +0100
                Re: "Lete2�™s Stop Bashing C" Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-06 16:49 -0500
                Re: "Lete2�™s Stop Bashing C" supercat@casperkitty.com - 2016-12-06 14:24 -0800
                Re: "Lete2�™s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 00:07 +0100
                Re: micro-architectural details Noob <root@127.0.0.1> - 2016-12-07 22:04 +0100
                Re: micro-architectural details jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 23:44 +0100
                Re: micro-architectural details BartC <bc@freeuk.com> - 2016-12-07 23:02 +0000
                Re: micro-architectural details Keith Thompson <kst-u@mib.org> - 2016-12-07 15:28 -0800
                Re: micro-architectural details Noob <root@127.0.0.1> - 2016-12-08 21:36 +0100
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-08 12:56 -0800
                Re: micro-architectural details Noob <root@127.0.0.1> - 2016-12-08 23:03 +0100
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-08 14:21 -0800
                Re: micro-architectural details Noob <root@127.0.0.1> - 2016-12-08 23:36 +0100
                Re: micro-architectural details BartC <bc@freeuk.com> - 2016-12-08 21:59 +0000
                Re: micro-architectural details Noob <root@127.0.0.1> - 2016-12-08 23:25 +0100
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-08 14:34 -0800
                Re: micro-architectural details Noob <root@127.0.0.1> - 2016-12-08 23:59 +0100
                Re: micro-architectural details Melzzzzz <mel@zzzzz.com> - 2016-12-09 00:18 +0100
                Re: micro-architectural details fir <profesor.fir@gmail.com> - 2016-12-09 00:06 -0800
                Re: micro-architectural details jt@toerring.de (Jens Thoms Toerring) - 2016-12-09 11:35 +0000
                Re: micro-architectural details BartC <bc@freeuk.com> - 2016-12-09 12:12 +0000
                Re: micro-architectural details David Brown <david.brown@hesbynett.no> - 2016-12-09 13:33 +0100
                Re: micro-architectural details Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-09 15:41 -0800
                Re: micro-architectural details Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-10 09:28 -0800
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-10 09:58 -0800
                Re: micro-architectural details Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-14 22:53 -0800
                Re: micro-architectural details Robert Wessel <robertwessel2@yahoo.com> - 2016-12-11 03:10 -0600
                Re: micro-architectural details jt@toerring.de (Jens Thoms Toerring) - 2016-12-11 13:48 +0000
                Re: micro-architectural details BartC <bc@freeuk.com> - 2016-12-11 14:43 +0000
                Re: micro-architectural details Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 16:23 +0000
                Re: micro-architectural details Keith Thompson <kst-u@mib.org> - 2016-12-11 12:53 -0800
                Re: micro-architectural details Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 21:27 +0000
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-11 08:46 -0800
                Re: micro-architectural details Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-14 21:14 -0800
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-15 08:25 -0800
                Re: micro-architectural details Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-14 21:11 -0800
                Re: micro-architectural details BartC <bc@freeuk.com> - 2016-12-15 14:28 +0000
                Re: micro-architectural details David Brown <david.brown@hesbynett.no> - 2016-12-11 18:38 +0100
                Re: micro-architectural details Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-15 00:25 -0800
                Re: micro-architectural details supercat@casperkitty.com - 2016-12-09 07:42 -0800
                Re: micro-architectural details Keith Thompson <kst-u@mib.org> - 2016-12-09 11:54 -0800
                Re: micro-architectural details David Brown <david.brown@hesbynett.no> - 2016-12-09 10:27 +0100
                Re: other missing features (no-brainers) Noob <root@127.0.0.1> - 2016-12-09 17:05 +0100
                Re: micro-architectural details jt@toerring.de (Jens Thoms Toerring) - 2016-12-09 09:51 +0000
                Re: "Lete2�™s Stop Bashing C" Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-06 20:42 -0500
                Re: "Lete2�™s Stop Bashing C" supercat@casperkitty.com - 2016-12-06 14:16 -0800
                Re: "Lete2�™s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 00:31 +0100
                Re: "Let's Stop Bashing C" Keith Thompson <kst-u@mib.org> - 2016-12-06 15:55 -0800
                Re: "Let's Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 01:01 +0100
                Re: "Lete2�™s Stop Bashing C" supercat@casperkitty.com - 2016-12-06 16:42 -0800
                Re: "Lete2�™s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 01:55 +0100
                Re: "Lete2�™s Stop Bashing C" supercat@casperkitty.com - 2016-12-07 07:11 -0800
                Re: "Lete2??s Stop Bashing C" Ike Naar <ike@iceland.freeshell.org> - 2016-12-06 23:05 +0000
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 00:43 +0100
                Re: "Lete2??s Stop Bashing C" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-07 03:06 +0000
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 11:47 +0100
                Re: "Lete2??s Stop Bashing C" Thiago Adams <thiago.adams@gmail.com> - 2016-12-07 03:10 -0800
                Re: "Lete2??s Stop Bashing C" Thiago Adams <thiago.adams@gmail.com> - 2016-12-07 03:13 -0800
                Re: "Lete2??s Stop Bashing C" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-07 11:47 +0000
                Re: "Lete2??s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-07 12:08 +0000
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-07 23:45 +0100
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 00:22 +0100
                Re: "Lete2??s Stop Bashing C" Keith Thompson <kst-u@mib.org> - 2016-12-07 15:32 -0800
                Re: "Let's Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 01:25 +0100
                Re: "Let's Stop Bashing C" supercat@casperkitty.com - 2016-12-07 16:36 -0800
                Re: "Let's Stop Bashing C" Keith Thompson <kst-u@mib.org> - 2016-12-07 17:09 -0800
                Re: "Let's Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 10:28 +0100
                Re: "Let's Stop Bashing C" Keith Thompson <kst-u@mib.org> - 2016-12-08 08:34 -0800
                Re: "Let's Stop Bashing C" Gareth Owen <gwowen@gmail.com> - 2016-12-08 20:08 +0000
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-08 10:24 +0100
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 15:49 +0100
                Re: "Lete2??s Stop Bashing C" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-08 15:23 +0000
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 16:58 +0100
                Re: "Lete2??s Stop Bashing C" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-08 18:57 +0000
                Re: "Lete2??s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-08 15:29 +0000
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 17:09 +0100
                Re: "Lete2??s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-08 16:41 +0000
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-08 17:04 +0100
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 17:15 +0100
                Re: "Lete2??s Stop Bashing C" Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-08 11:34 -0500
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 18:40 +0100
                Re: "Lete2??s Stop Bashing C" supercat@casperkitty.com - 2016-12-08 10:00 -0800
                Re: "Lete2??s Stop Bashing C" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-08 19:05 +0000
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-08 19:58 +0100
                Re: "Lete2??s Stop Bashing C" supercat@casperkitty.com - 2016-12-08 08:22 -0800
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-08 20:12 +0100
                Re: "Lete2??s Stop Bashing C" supercat@casperkitty.com - 2016-12-08 11:40 -0800
                Re: "Lete2??s Stop Bashing C" Robert Wessel <robertwessel2@yahoo.com> - 2016-12-10 02:44 -0600
                Re: "Lete2??s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-08 16:22 +0000
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-08 20:14 +0100
                Re: "Lete2??s Stop Bashing C" Robert Wessel <robertwessel2@yahoo.com> - 2016-12-10 02:19 -0600
                Re: "Lete2??s Stop Bashing C" supercat@casperkitty.com - 2016-12-08 07:44 -0800
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-08 22:05 +0100
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-08 22:14 +0100
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-09 10:39 +0100
                Re: "Lete2??s Stop Bashing C" supercat@casperkitty.com - 2016-12-08 13:33 -0800
                Re: "Lete2??s Stop Bashing C" David Brown <david.brown@hesbynett.no> - 2016-12-09 11:13 +0100
                Re: "Lete2??s Stop Bashing C" Robert Wessel <robertwessel2@yahoo.com> - 2016-12-07 06:27 -0600
                Re: "Lete2??s Stop Bashing C" supercat@casperkitty.com - 2016-12-07 07:17 -0800
                Re: "Lete2??s Stop Bashing C" Robert Wessel <robertwessel2@yahoo.com> - 2016-12-07 23:43 -0600
                Re: "Lete2??s Stop Bashing C" Ike Naar <ike@iceland.freeshell.org> - 2016-12-07 07:41 +0000
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 11:45 +0100
                Re: "Lete2??s Stop Bashing C" Keith Thompson <kst-u@mib.org> - 2016-12-07 09:22 -0800
                Re: "Lete2??s Stop Bashing C" jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-07 11:49 +0100
                Re: "Lete2??s Stop Bashing C" Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-07 09:28 -0500
            Re: "Lete2��s Stop Bashing C" "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-06 14:22 -0500
            Re: Subject field encoding Noob <root@127.0.0.1> - 2016-12-07 21:40 +0100
              Re: Subject field encoding Keith Thompson <kst-u@mib.org> - 2016-12-07 13:01 -0800
              Re: Subject field encoding Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-07 16:02 -0500
            Re: "Lete2�™s Stop Bashing C" asetofsymbols@gmail.com - 2016-12-08 15:50 -0800
          Re: "Let’s Stop Bashing C" Richard Heathfield <rjh@cpax.org.uk> - 2016-12-06 19:07 +0000
    Re: "Let€™s Stop Bashing C" Xcott Craver <nospam@nospam.invalid> - 2016-12-07 16:48 -0500
      Re: "Let's Stop Bashing C" Noob <root@127.0.0.1> - 2016-12-07 23:29 +0100
  Re: "Let’s Stop Bashing C" "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2016-12-06 12:06 +0800

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