Re: Good hash for pointers

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Sujet : Re: Good hash for pointers
De : richard.nospam (at) *nospam* gmail.invalid (Richard Harnden)
Groupes : comp.lang.c
Date : 23. May 2024, 15:37:44
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Organisation : A noiseless patient Spider
Message-ID : <v2nkbq$1pt1p$1@dont-email.me>
References : 1
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On 23/05/2024 12:11, Malcolm McLean wrote:
 What is a good hash function for pointers to use in portable ANSI C?
All your pointers from malloc are going to be unique.
All of their low bits are going to be zero, because they need to align on some n-bit boundary.
All of their high bit are going to be the same, because that's just how it works.
So just take the middle:  hash = ((intptr_t) ptr) >> 4 & 0xffff;
Good enough?

Date Sujet#  Auteur
23 May 24 * Good hash for pointers111Malcolm McLean
23 May 24 +* Re: Good hash for pointers3Richard Harnden
24 May 24 i`* Re: Good hash for pointers2Keith Thompson
24 May 24 i `- Re: Good hash for pointers1Malcolm McLean
23 May 24 +- Re: Good hash for pointers1Kaz Kylheku
24 May 24 +* Re: Good hash for pointers16Tim Rentsch
24 May 24 i`* Re: Good hash for pointers15Malcolm McLean
24 May 24 i `* Re: Good hash for pointers14Tim Rentsch
24 May 24 i  `* Re: Good hash for pointers13Malcolm McLean
24 May 24 i   +* Re: Good hash for pointers11Tim Rentsch
24 May 24 i   i`* Re: Good hash for pointers10bart
24 May 24 i   i +* Re: Good hash for pointers3Malcolm McLean
24 May 24 i   i i`* Re: Good hash for pointers2Chris M. Thomasson
24 May 24 i   i i `- Re: Good hash for pointers1Chris M. Thomasson
24 May 24 i   i +* Re: Good hash for pointers3Tim Rentsch
24 May 24 i   i i`* Re: Good hash for pointers2Malcolm McLean
25 May 24 i   i i `- Re: Good hash for pointers1Tim Rentsch
24 May 24 i   i `* Re: Good hash for pointers3David Brown
24 May 24 i   i  `* Re: Good hash for pointers2Malcolm McLean
24 May 24 i   i   `- Re: Good hash for pointers1Michael S
24 May 24 i   `- Re: Good hash for pointers1David Brown
24 May 24 +* Re: Good hash for pointers3Chris M. Thomasson
24 May 24 i`* Re: Good hash for pointers2Chris M. Thomasson
24 May 24 i `- Re: Good hash for pointers1jak
24 May 24 +* Re: Good hash for pointers84Bonita Montero
24 May 24 i`* Re: Good hash for pointers83Malcolm McLean
25 May 24 i `* Re: Good hash for pointers82bart
25 May 24 i  `* Re: Good hash for pointers81Tim Rentsch
25 May 24 i   +* Re: Good hash for pointers4bart
25 May 24 i   i`* Re: Good hash for pointers3Tim Rentsch
25 May 24 i   i `* Re: Good hash for pointers2bart
26 May 24 i   i  `- Re: Good hash for pointers1Tim Rentsch
25 May 24 i   `* Re: Good hash for pointers76Bonita Montero
25 May 24 i    `* Re: Good hash for pointers75Tim Rentsch
25 May 24 i     +* Re: Good hash for pointers9Malcolm McLean
25 May 24 i     i+- Re: Good hash for pointers1Tim Rentsch
25 May 24 i     i+* Re: Good hash for pointers5Janis Papanagnou
26 May 24 i     ii`* Re: Good hash for pointers4Malcolm McLean
26 May 24 i     ii `* Re: Good hash for pointers3bart
26 May 24 i     ii  +- Re: Good hash for pointers1Richard Harnden
27 May 24 i     ii  `- Re: Good hash for pointers1Kaz Kylheku
26 May 24 i     i`* Re: Good hash for pointers2Bonita Montero
26 May 24 i     i `- Re: Good hash for pointers1Bonita Montero
26 May 24 i     `* Re: Good hash for pointers65Bonita Montero
26 May 24 i      `* Re: Good hash for pointers64Tim Rentsch
26 May 24 i       `* Re: Good hash for pointers63Bonita Montero
26 May 24 i        `* Re: Good hash for pointers62Tim Rentsch
26 May 24 i         +* Re: Good hash for pointers29Bonita Montero
26 May 24 i         i+- Re: Good hash for pointers1Bonita Montero
27 May 24 i         i+* Re: Good hash for pointers5Bonita Montero
28 May 24 i         ii`* Re: Good hash for pointers4Ben Bacarisse
30 May 24 i         ii `* Re: Good hash for pointers3Bonita Montero
30 May 24 i         ii  +- Re: Good hash for pointers1Bonita Montero
31 May 24 i         ii  `- Re: Good hash for pointers1Tim Rentsch
31 May 24 i         i`* Re: Good hash for pointers22Tim Rentsch
2 Jun 24 i         i `* Re: Good hash for pointers21Michael S
2 Jun 24 i         i  +* Re: Good hash for pointers2Chris M. Thomasson
3 Jun 24 i         i  i`- Re: Good hash for pointers1Chris M. Thomasson
3 Jun 24 i         i  +* Re: Good hash for pointers5Tim Rentsch
3 Jun 24 i         i  i`* Re: Good hash for pointers4Michael S
4 Jun 24 i         i  i `* Re: Good hash for pointers3Tim Rentsch
4 Jun 24 i         i  i  `* Re: Good hash for pointers2Michael S
5 Jun 24 i         i  i   `- Re: Good hash for pointers1Tim Rentsch
3 Jun 24 i         i  `* Re: Good hash for pointers13Bonita Montero
3 Jun 24 i         i   `* Re: Good hash for pointers12Michael S
3 Jun 24 i         i    `* Re: Good hash for pointers11Bonita Montero
3 Jun 24 i         i     +* Re: Good hash for pointers8bart
3 Jun 24 i         i     i+* Re: Good hash for pointers6Michael S
3 Jun 24 i         i     ii+* Re: Good hash for pointers4bart
3 Jun 24 i         i     iii+- Re: Good hash for pointers1Michael S
3 Jun 24 i         i     iii+- Re: Good hash for pointers1Michael S
4 Jun 24 i         i     iii`- Re: Good hash for pointers1Tim Rentsch
4 Jun 24 i         i     ii`- Re: Good hash for pointers1Tim Rentsch
3 Jun 24 i         i     i`- Re: Good hash for pointers1Bonita Montero
3 Jun 24 i         i     `* Re: Good hash for pointers2Michael S
3 Jun 24 i         i      `- Re: Good hash for pointers1Bonita Montero
4 Jun 24 i         `* Re: Good hash for pointers32Michael S
5 Jun 24 i          +* Re: Good hash for pointers4Bonita Montero
5 Jun 24 i          i`* Re: Good hash for pointers3Michael S
5 Jun 24 i          i `* Re: Good hash for pointers2Bonita Montero
5 Jun 24 i          i  `- Re: Good hash for pointers1Michael S
5 Jun 24 i          +* Re: Good hash for pointers17Tim Rentsch
5 Jun 24 i          i+* AES problem (was: Good hash for pointers)2Michael S
6 Jun 24 i          ii`- Re: AES problem (was: Good hash for pointers)1Tim Rentsch
5 Jun 24 i          i+* Re: Good hash for pointers11Michael S
6 Jun 24 i          ii`* Re: Good hash for pointers10Tim Rentsch
6 Jun 24 i          ii `* Re: Good hash for pointers9Michael S
17 Jun 24 i          ii  `* Re: Good hash for pointers8Tim Rentsch
17 Jun 24 i          ii   `* Re: Good hash for pointers7Michael S
18 Jun 24 i          ii    `* Re: Good hash for pointers6Tim Rentsch
19 Jun 24 i          ii     +* Re: Good hash for pointers2Keith Thompson
19 Jun 24 i          ii     i`- Re: Good hash for pointers1Tim Rentsch
19 Jun 24 i          ii     `* Re: Good hash for pointers3James Kuyper
19 Jun 24 i          ii      +- Re: Good hash for pointers1Keith Thompson
23 Jun 24 i          ii      `- Re: Good hash for pointers1Tim Rentsch
6 Jun 24 i          i`* Re: Good hash for pointers3Michael S
16 Jun 24 i          i `* Re: Good hash for pointers2Tim Rentsch
16 Jun 24 i          i  `- Re: Good hash for pointers1Chris M. Thomasson
7 Jun 24 i          `* Re: Good hash for pointers10Bonita Montero
9 Jun 24 i           `* Re: Good hash for pointers9Bonita Montero
9 Jun 24 i            +* Re: Good hash for pointers2Richard Harnden
10 Jun 24 i            `* Re: Good hash for pointers6Malcolm McLean
26 May 24 +* Re: Good hash for pointers2Bonita Montero
26 May 24 `- Re: Good hash for pointers1Bonita Montero

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