From alarsson@cmu.edu Wed Jul 12 18:06:18 1995
Path: ashpoly!cascade!mxgate!coyoacan!cmu!alarsson
From: alarsson@cmu.edu (Amy Larsson)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Jul12.180618.3809@cmu.edu>
Date: Wed, 12 Jul 1995 18:06:18 GMT
Organization: Carnegie Mellon University School of CS
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Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.

However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.
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.

-- 
Amy Larsson | alarsson@cmu.edu
PGP Key fingerprint: DC7D B1AE 7158 E696
"Keep the channels open."

From esantos@cmu.edu Thu Jul 13 17:55:18 1995
Path: ashpoly!cascade!bigsur!cmu!esantos
From: esantos@cmu.edu (Elaine Santos)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Jul13.175518.1429@cmu.edu>
Date: Thu, 13 Jul 1995 17:55:18 GMT
References: <1995Jul12.180618.3809@cmu.edu>
Organization: Carnegie Mellon University School of CS
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In article <1995Jul12.180618.3809@cmu.edu>, alarsson@cmu.edu (Amy Larsson) writes:
> Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.
> However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.

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

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-- 
Elaine Santos -- Carnegie Mellon University School of CS
"The carrier frequency does not drift by accident."