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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Good hash for pointers
Date: Thu, 23 May 2024 18:59:19 -0700
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On 5/23/2024 5:32 PM, Chris M. Thomasson wrote:
> On 5/23/2024 4:11 AM, Malcolm McLean wrote:
>>
>> What is a good hash function for pointers to use in portable ANSI C?
>>
>> The pointers are nodes of a tree, which are read only, and I want to 
>> associate read/write data with them. So potentially a lage number of 
>> pointers,and they might be consecutively ordered if they are taken 
>> from an array, or they might be returned from repeared calls to 
>> malloc() with small allocations. Obviously I have no control over 
>> pointer size or internal representation.
>>
> 
> I kind of remember an old one for 32-bit pointers. It was something like 
> multiply by a prime and shift to the right by 7 or 8. Shit, I think. It 
> was way back on comp.programming.threads.

There was an old paper from microsoft that had a pointer hash. It was 
used to index into a table of locks. I need to find it.