From: DavMac AT iname DOT com (Davin McCall)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Re[2]: Bit counting?
Date: Tue, 17 Aug 1999 06:33:31 GMT
Organization: Monash Uni
Lines: 33
Distribution: world
Message-ID: <37b9010b.24972024@newsserver.cc.monash.edu.au>
References: <37b4e020 DOT 2582291 AT newsserver DOT cc DOT monash DOT edu DOT au> <792 DOT 990817 AT Phreaker DOT net>
NNTP-Posting-Host: damcc5.halls.monash.edu.au
X-Trace: towncrier.cc.monash.edu.au 934871554 4282 130.194.198.138 (17 Aug 1999 06:32:34 GMT)
X-Complaints-To: abuse AT monash DOT edu DOT au
NNTP-Posting-Date: 17 Aug 1999 06:32:34 GMT
X-Newsreader: Forte Free Agent 1.1/32.230
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

You are using "value" each time. You should only use it the first
time, and use "tempvalue" after that. To use your example (value = 7d
= 111b, 3 bits are set):

>2 bit sequemce:
>value = 7
>mask1 = 0000000000000111 & 0101010101010101 = 5
>mask2 = 0000000000000111 & 1010101010101010 = 2
>mask2 >>=1 = 1
>tempvalue = mask1 + mask2 = 5 + 1 = 6


>4 bit sequence:
>value = 7
----> rather, tempvalue = 6  
>mask1 = 0000000000000111 & 0011001100110011 = 3
>mask2 = 0000000000000111 & 1100110011001100 = 4
---> mask1 = 00000000000110 & 0011001100110011 = 2
     mask2 = 00000000000110 & 1100110011001100 = 4
>mask2 >>= 2 = 1
>tempvalue = mask1 + mask2 = 3 + 1 = 4
   .. = 2 + 1 = 3.

Continuing the process will not change the value; "3" is the final
answer.

Hope this made things clear,

Davin.

__________________________________________________________
       *** davmac - sharkin'!! davmac AT iname DOT com ***
my programming page: http://yoyo.cc.monash.edu.au/~davmac/