-----Original Message-----
From: William Chops Westfield <billw@CISCO.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Thursday, 30 October 1997 18:04
Subject: Re: Challenge: Reverse 7 bits


>There is a clever algorithm for bit reversal "discovered" at MIT (I
>think) a long time ago.  Do:
>
>        mult a,#100040020001            ;Make some copies
>        and a, #210210210010            ; select some bits
>        div a, #377                     ; cast out / squeeze...
>
>All the numbers are octal.  The words are 36 bits long and the initial
>multiply is allowed to get an arithmatic overflow.
>Three instuctions. Five words (36 bits each).  Totally inapplicable to
>the PIC, but pretty weird...
>


Typical assembly comments!  <g>

Anyone care to explain it?

MikeS
<mikesmith_oz@relaymail.net>