Re: Good hash for pointers

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: Good hash for pointers
Date	2024-05-24 06:18 -0700
Organization	A noiseless patient Spider
Message-ID	<865xv3ic14.fsf@linuxsc.com> (permalink)
References	(2 earlier) <v2okbv$1vp4n$2@dont-email.me> <86r0dshysc.fsf@linuxsc.com> <v2omvt$2049k$1@dont-email.me> <86ed9shtsj.fsf@linuxsc.com> <v2ppac$29ca1$1@dont-email.me>

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bart <bc@freeuk.com> writes:

> On 24/05/2024 02:39, Tim Rentsch wrote:
>
>> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
>>
>>> On 24/05/2024 00:52, Tim Rentsch wrote:
>>>
>>>> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
>>>>
>>>>> On 23/05/2024 23:49, Tim Rentsch wrote:
>>>>>
>>>>>> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
>>>>>>
>>>>>>> What is a good hash function for pointers to use in portable
>>>>>>> ANSI C?
>>>>>>
>>>>>> I have a preliminary question.  Do you really mean ANSI C, or
>>>>>> is C99 acceptable?
>>>>>
>>>>> C89 is better.
>>>>> But the pass has been sold.
>>>>
>>>> I'm not asking which you think is better.  I'm asking about
>>>> what your requirements are.
>>>
>>> C 89.
>>> I don't want to pull in C99 types and so on just for a hash
>>> function.
>>
>> In that case I think you are stuck with using a half-baked
>> solution.  The standard integer types available in C89 just
>> aren't a good fit in a 64-bit world.
>
> I assume the C89 implementation is one that can target current 64
> bit machines.
>
> Then char, short, int, long long will almost certainly have widths
> of 8, 16, 32 and 64 bits respectively.

C89 doesn't have long long.

> (I don't know if 'long long' was part of C89, but it sounds like
> Malcolm just doesn't want to be bothered with stdint.h, and any
> compiler used is like to support it.

What he said was C89.  He didn't mention stdint.h.  I take
him at his word.  If what he wants is something different,
he should say clearly what it is, and not make people guess
about it.  (To be clear this recommendation is intended for
every questioner, not just Malcolm.)

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Thread

Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-23 12:11 +0100
  Re: Good hash for pointers Richard Harnden <richard.nospam@gmail.invalid> - 2024-05-23 15:37 +0100
    Re: Good hash for pointers Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-05-23 15:51 -0700
      Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 00:42 +0100
  Re: Good hash for pointers Kaz Kylheku <643-408-1753@kylheku.com> - 2024-05-23 20:34 +0000
  Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-23 15:49 -0700
    Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 00:43 +0100
      Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-23 16:52 -0700
        Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 01:28 +0100
          Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-23 18:39 -0700
            Re: Good hash for pointers bart <bc@freeuk.com> - 2024-05-24 11:14 +0100
              Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 12:05 +0100
                Re: Good hash for pointers "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-05-24 10:49 -0700
                Re: Good hash for pointers "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-05-24 10:51 -0700
              Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-24 06:18 -0700
                Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 15:07 +0100
                Re: Good hash for pointers scott@slp53.sl.home (Scott Lurndal) - 2024-05-24 14:51 +0000
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-25 02:49 -0700
              Re: Good hash for pointers David Brown <david.brown@hesbynett.no> - 2024-05-24 17:00 +0200
                Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 17:10 +0100
                Re: Good hash for pointers Michael S <already5chosen@yahoo.com> - 2024-05-24 19:27 +0300
          Re: Good hash for pointers David Brown <david.brown@hesbynett.no> - 2024-05-24 09:41 +0200
  Re: Good hash for pointers "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-05-23 17:32 -0700
    Re: Good hash for pointers "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-05-23 18:59 -0700
      Re: Good hash for pointers jak <nospam@please.ty> - 2024-05-24 04:09 +0200
  Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-24 20:28 +0200
    Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-24 19:57 +0100
      Re: Good hash for pointers bart <bc@freeuk.com> - 2024-05-25 00:54 +0100
        Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-25 02:12 -0700
          Re: Good hash for pointers bart <bc@freeuk.com> - 2024-05-25 12:28 +0100
            Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-25 11:12 -0700
              Re: Good hash for pointers bart <bc@freeuk.com> - 2024-05-25 20:31 +0100
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-25 22:54 -0700
          Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-25 17:00 +0200
            Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-25 10:40 -0700
              Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-25 18:56 +0100
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-25 11:23 -0700
                Re: Good hash for pointers Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-05-25 23:13 +0200
                Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-25 23:07 +0100
                Re: Good hash for pointers bart <bc@freeuk.com> - 2024-05-25 23:42 +0100
                Re: Good hash for pointers Richard Harnden <richard.nospam@gmail.invalid> - 2024-05-26 19:58 +0100
                Re: Good hash for pointers Kaz Kylheku <643-408-1753@kylheku.com> - 2024-05-26 22:42 +0000
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 18:05 +0200
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 18:07 +0200
              Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 18:04 +0200
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-26 09:24 -0700
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 18:36 +0200
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-26 10:20 -0700
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 19:39 +0200
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 19:54 +0200
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-27 08:07 +0200
                Re: Good hash for pointers Ben Bacarisse <ben@bsb.me.uk> - 2024-05-28 11:07 +0100
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-30 10:10 +0200
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-30 11:27 +0200
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-30 19:26 -0700
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-05-30 19:27 -0700
                Re: Good hash for pointers Michael S <already5chosen@yahoo.com> - 2024-06-02 10:45 +0300
                Re: Good hash for pointers "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-02 12:42 -0700
                Re: Good hash for pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-02 16:02 -0700
                Re: Good hash for pointers Michael S <already5chosen@yahoo.com> - 2024-06-03 10:50 +0300
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-03 16:34 +0200
                Re: Good hash for pointers Michael S <already5chosen@yahoo.com> - 2024-06-03 17:46 +0300
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-03 17:54 +0200
                Re: Good hash for pointers bart <bc@freeuk.com> - 2024-06-03 17:24 +0100
                Re: Good hash for pointers Michael S <already5chosen@yahoo.com> - 2024-06-03 20:16 +0300
                Re: Good hash for pointers bart <bc@freeuk.com> - 2024-06-03 19:48 +0100
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-03 20:25 +0200
                Re: Good hash for pointers Michael S <already5chosen@yahoo.com> - 2024-06-03 19:50 +0300
                Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-03 20:31 +0200
  Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 20:06 +0200
    Re: Good hash for pointers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-05-26 20:10 +0100
  Re: Good hash for pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-05-26 20:24 +0200

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