1994-07-07 - Bit counting
Header Data
From: Ian Farquhar <ifarqhar@laurel.ocs.mq.edu.au>
To: cypherpunks@toad.com
Message Hash: 1d7314d1fe69719702cb22aa2ae19b81662c71b4783d84df622e8a4c64309ac8
Message ID: <199407070257.AA00900@laurel.ocs.mq.edu.au>
Reply To: N/A
UTC Datetime: 1994-07-07 02:58:27 UTC
Raw Date: Wed, 6 Jul 94 19:58:27 PDT
Raw message
From: Ian Farquhar <ifarqhar@laurel.ocs.mq.edu.au>
Date: Wed, 6 Jul 94 19:58:27 PDT
To: cypherpunks@toad.com
Subject: Bit counting
Message-ID: <199407070257.AA00900@laurel.ocs.mq.edu.au>
MIME-Version: 1.0
Content-Type: text/plain
>Why bother when you can simply do an eight line function?
>int bitcount(char b)
>{
>register int retval=0;
> if (a & 1) retval++;
> if (a & 2) retval++;
> if (a & 4) retval++;
> if (a & 8) retval++;
> if (a & 16) retval++;
> if (a & 32) retval++;
> if (a & 64) retval++;
> if (a & 128) retval++;
>return retval;
>}
[...]
Because on a lot of architectures this implementation may be hideously
inefficient. All the world is not an Intel chip, thank god.
Ian.
Thread
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- 1994-07-07 (Wed, 6 Jul 94 19:58:27 PDT) - Bit counting - Ian Farquhar <ifarqhar@laurel.ocs.mq.edu.au>
- 1994-07-07 (Thu, 7 Jul 94 04:53:19 PDT) - Re: Bit counting - tim werner <werner@mc.ab.com>
- 1994-07-10 (Sat, 9 Jul 94 23:48:34 PDT) - Re: Bit counting - rarachel@prism.poly.edu (Arsen Ray Arachelian)