From tsanchez@u-tokyo.ac.jp Thu Feb 23 11:10:35 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!u-tokyo!tsanchez
From: tsanchez@u-tokyo.ac.jp (Tobias Sánchez)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Feb23.111035.7035@u-tokyo.ac.jp>
Date: Thu, 23 Feb 1995 11:10:35 GMT
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Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.

The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead.
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.

-- 
Tobias Sánchez
Tape trading list upon request. SASE required for international mail.

From tschneider@tum.de Fri Feb 24 18:48:35 1995
Path: ashpoly!cascade!bigsur!tum!tschneider
From: tschneider@tum.de (Takeshi Schneider)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Feb24.184835.2648@tum.de>
Date: Fri, 24 Feb 1995 18:48:35 GMT
References: <1995Feb23.111035.7035@u-tokyo.ac.jp>
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In article <1995Feb23.111035.7035@u-tokyo.ac.jp>, tsanchez@u-tokyo.ac.jp (Tobias Sánchez) writes:
> Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.

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

-- 
Takeshi Schneider -- Technische Universität München
"They will send a copy in my place."