Path: utzoo!utgpu!water!watmath!clyde!rutgers!mit-eddie!bloom-beacon!athena.mit.edu!eichin
From: eichin@athena.mit.edu (Mark W. Eichin)
Newsgroups: comp.lang.c
Subject: Re: XOR-trick and PUZZLE (was comma-operator)
Summary: Use it for redundancy
Keywords: BYTE xor files
Message-ID: <2484@bloom-beacon.MIT.EDU>
Date: 23 Jan 88 21:19:44 GMT
References: <269@vsi1.UUCP> <226@goofy.megatest.UUCP>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: eichin@athena.mit.edu (Mark W. Eichin)
Organization: Mercury, Io and Titan
Lines: 20

In article <226@goofy.megatest.UUCP> djones@megatest.UUCP (Dave Jones) writes:
>PUZZLE for those lucky enough not to have seen it previously:
>
>How can you use the XOR trick to keep a doubly linked list, using only
>one field for in each record, to code for finding both the following and 
>the previous record?  
I recall seeing an article in BYTE about five years back on using this
for a floppy disk file management technique... I think the suggestion
was to keep it as an extra pointer to recover from, but from a given
record you could always find the `next' record. Anybody recall the
reference in more detail?
				Mark Eichin
			<eichin@athena.mit.edu>
		SIPB Member & Project Athena ``Watchmaker'' 



				Mark Eichin
			<eichin@athena.mit.edu>
		SIPB Member & Project Athena ``Watchmaker''