Path: utzoo!utgpu!news-server.csri.toronto.edu!neuron.ai.toronto.edu!radford
Newsgroups: comp.compression
From: radford@ai.toronto.edu (Radford Neal)
Subject: Re: Sound compression
Message-ID: <91May15.140250edt.750@neuron.ai.toronto.edu>
Keywords: sound compression
Organization: Department of Computer Science, University of Toronto
References: <16198@helios.TAMU.EDU> <19524@crdgw1.crd.ge.com> <104045@sgi.sgi.com>
Date: 15 May 91 18:03:08 GMT
Lines: 16

In article <104045@sgi.sgi.com> rpw3@sgi.com (Rob Warnock) writes:

>By the way, there was a paper in CACM (??? sorry, forgot the ref) a number
>of years ago which proved that there is no closed functional form without
>conditionals which will compute "the highest-order one bit".

Actually, you should be able to quickly find the position of the 
highest-order one bit of an integer on most machines with floating-point
instructions by jamming the integer into the mantissa part of a floating-
point number, along with some appropriate exponent, and then performing
some operation that will induce the floating-point processor to do a
normalization. The number of the highest-order one bit in the original
integer should then be readily obtainable by examining the exponent part
of the normalized floating-point result.

   Radford Neal