From bramirez@rwth-aachen.de Wed Jul 13 16:05:00 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!rwth-aachen!bramirez
From: bramirez@rwth-aachen.de (Bastien Ramírez)
Newsgroups: comp.dsp
Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Jul13.160500.2453@rwth-aachen.de>
Date: Wed, 13 Jul 1994 16:05:00 GMT
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Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

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

Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm.

-- 
Bastien Ramírez
Opinions expressed are solely my own and not those of RWTH Aachen Informatik.
------------------------------------------------------------

From kpopov@panix.com Thu Jul 14 14:21:00 1994
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From: kpopov@panix.com (Katrin Popov)
Newsgroups: comp.dsp
Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Jul14.142100.4926@panix.com>
Date: Thu, 14 Jul 1994 14:21:00 GMT
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In article <1994Jul13.160500.2453@rwth-aachen.de>, bramirez@rwth-aachen.de (Bastien Ramírez) writes:
> Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

-- 
=== Katrin Popov ===
Dept of Electrical Engineering, Public Access Unix of New York
"There are 14 nodes and only 10 countries. Count again."