From ykim@purdue.edu Sat Apr 23 06:23:10 1994
Path: ashpoly!cascade!bigsur!purdue!ykim
From: ykim@purdue.edu (Yuki Kim)
Newsgroups: comp.dsp
Subject: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Apr23.062310.3322@purdue.edu>
Date: Sat, 23 Apr 1994 06:23:10 GMT
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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.

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

-- 
=== Yuki Kim ===
Dept of Electrical Engineering, Purdue University Engineering Computer Network
"Hold for relay."

From ssato@utexas.edu Sun Apr 24 04:40:10 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!utexas!ssato
From: ssato@utexas.edu (Sergei Sato)
Newsgroups: comp.dsp
Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Apr24.044010.7844@utexas.edu>
Date: Sun, 24 Apr 1994 04:40:10 GMT
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In article <1994Apr23.062310.3322@purdue.edu>, ykim@purdue.edu (Yuki Kim) 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.

-- 
Sergei Sato
Tape trading list upon request. SASE required for international mail.