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From: Bonita Montero <Bonita.Montero@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Good hash for pointers
Date: Sun, 26 May 2024 18:36:25 +0200
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Am 26.05.2024 um 18:24 schrieb Tim Rentsch:
> Bonita Montero <Bonita.Montero@gmail.com> writes:
> 
>> Am 25.05.2024 um 19:40 schrieb Tim Rentsch:
>>
>>> Bonita Montero <Bonita.Montero@gmail.com> writes:
>>>
>>>> Am 25.05.2024 um 11:12 schrieb Tim Rentsch:
>>>>
>>>>> Your hash function is expensive to compute, moreso even
>>>>> than the "FNV" function shown earlier.  In a case like
>>>>> this one where the compares are cheap, it's better to
>>>>> have a dumb-but-fast hash function that might need a
>>>>> few more looks to find an open slot, because the cost
>>>>> of looking is so cheap compared to computing the hash
>>>>> function.
>>>>
>>>> A (size_t)pointer * LARGE_PRIME can be sufficient,
>>>> ignoring the overflow.
>>>
>>> Plenty fast but the output quality is poor. ...
>>
>> If the prime is large enough there'e no regular distribution.
> 
> Your conjecture is contradicted by empirical facts.

There are no empirival facts for that since two times the
taken prime is beyond the 64 bit address space.