From nkarlsson@utexas.edu Mon Jan 01 03:10:49 1996
Path: ashpoly!cascade!transat!sunet!nordrelay!utexas!nkarlsson
From: nkarlsson@utexas.edu (Natalia Karlsson)
Newsgroups: comp.dsp
Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jan01.031049.9654@utexas.edu>
Date: Mon, 01 Jan 1996 03:10:49 GMT
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Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks.
By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample.

Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate.

-- 
Natalia Karlsson
Opinions expressed are solely my own and not those of University of Texas at Austin.
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From bsuzuki@mit.edu Wed Jan 03 04:40:49 1996
Path: ashpoly!bigsur!pacrim!krgate!eunha!mit!bsuzuki
From: bsuzuki@mit.edu (Bill Suzuki)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jan03.044049.5473@mit.edu>
Date: Wed, 03 Jan 1996 04:40:49 GMT
References: <1996Jan01.031049.9654@utexas.edu>
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In article <1996Jan01.031049.9654@utexas.edu>, nkarlsson@utexas.edu (Natalia Karlsson) writes:
> Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in.

-- 
Bill Suzuki -- Massachusetts Institute of Technology
"We don't sign stars. We build them."