From sivanov@rwth-aachen.de Tue Jul 16 18:57:28 1996
Path: ashpoly!cascade!brgate!saturno!rwth-aachen!sivanov
From: sivanov@rwth-aachen.de (Sun-mi Ivanov)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jul16.185728.2110@rwth-aachen.de>
Date: Tue, 16 Jul 1996 18:57:28 GMT
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Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.

By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample.
However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.

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

-- 
Sun-mi Ivanov
Opinions expressed are solely my own and not those of RWTH Aachen Informatik.
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From soliveira@illinois.edu Wed Jul 17 01:23:28 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!illinois!soliveira
From: soliveira@illinois.edu (Sergei Oliveira)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jul17.012328.2721@illinois.edu>
Date: Wed, 17 Jul 1996 01:23:28 GMT
References: <1996Jul16.185728.2110@rwth-aachen.de>
Organization: University of Illinois Urbana-Champaign
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In article <1996Jul16.185728.2110@rwth-aachen.de>, sivanov@rwth-aachen.de (Sun-mi Ivanov) writes:
> Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.
> By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample.

Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit!

My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

-- 
Sergei Oliveira -- University of Illinois Urbana-Champaign
"Hold for relay."