Date: Thu, 28 Aug 2003 06:17:46 +0300
Subject: Re: Lockless file reading
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Cc: root@chaos.analogic.com, Martin Konold <martin.konold@erfrakon.de>,
       linux-kernel@vger.kernel.org
To: Jamie Lokier <jamie@shareable.org>
From: Timo Sirainen <tss@iki.fi>
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On Thursday, Aug 28, 2003, at 04:50 Europe/Helsinki, Jamie Lokier wrote:

>> 	checksum[0]++;
>> 	xor = buf[0] ^ checksum[0];
>
> Your algorithm isn't going to work if the new value of xor is the same
> as the old value of xor.

I was trying to prevent it with the checksum[0]++ .. but yes, you're 
right.

I'm sure someone has figured out a way to make a checksum of data that 
can detect if there's even a single bit wrong, if the checksum is 
allowed to take as much space as the data itself. I should read more 
about algorithms..

How about checksum[n] = data[n-1] ^ data[n]? That looks like it would 
work.

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