From vfischer@mindspring.com Fri Jul 21 03:59:43 1995
Path: ashpoly!cascade!transat!ukc!fennimore!mindspring!vfischer
From: vfischer@mindspring.com (Valeria Fischer)
Newsgroups: comp.dsp
Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Jul21.035943.4807@mindspring.com>
Date: Fri, 21 Jul 1995 03:59:43 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.

-- 
Valeria Fischer
Opinions expressed are solely my own and not those of MindSpring Enterprises.
------------------------------------------------------------

From mrodriguez@demon.co.uk Sun Jul 23 07:06:43 1995
Path: ashpoly!cascade!mxgate!coyoacan!demon!mrodriguez
From: mrodriguez@demon.co.uk (Marisol Rodríguez)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Jul23.070643.9160@demon.co.uk>
Date: Sun, 23 Jul 1995 07:06:43 GMT
References: <1995Jul21.035943.4807@mindspring.com>
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In article <1995Jul21.035943.4807@mindspring.com>, vfischer@mindspring.com (Valeria Fischer) writes:
> 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.

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

-- 
=== Marisol Rodríguez ===
Dept of Electrical Engineering, Demon Internet Services UK
"Do not worship the copy."