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From: jak <nospam@please.ty>
Newsgroups: comp.lang.c
Subject: Re: Good hash for pointers
Date: Fri, 24 May 2024 04:09:41 +0200
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Chris M. Thomasson ha scritto:
> 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.

<https://wiki.osdev.org/Global_Descriptor_Table>