From aivanov@panix.com Mon Aug 21 18:50:48 1995
Path: ashpoly!cascade!transat!ukc!fennimore!panix!aivanov
From: aivanov@panix.com (Anja Ivanov)
Newsgroups: comp.dsp
Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Aug21.185048.2452@panix.com>
Date: Mon, 21 Aug 1995 18:50:48 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.
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.

-- 
=== Anja Ivanov ===
Dept of Electrical Engineering, Public Access Unix of New York
"Hardware is temporary. The signal survives."

From avasiliev@hanse.de Tue Aug 22 12:55:48 1995
Path: ashpoly!cascade!bigsur!hanse!avasiliev
From: avasiliev@hanse.de (Astrid Vasiliev)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Aug22.125548.2088@hanse.de>
Date: Tue, 22 Aug 1995 12:55:48 GMT
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In article <1995Aug21.185048.2452@panix.com>, aivanov@panix.com (Anja 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.

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

If you are posting from AOL, please read RFC 1036 before posting again.

-- 
Astrid Vasiliev -- Hanse-Netzwerk Hamburg
"They will send a copy in my place."

From bkarlsson@ox.ac.uk Thu Aug 24 12:59:48 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!ox!bkarlsson
From: bkarlsson@ox.ac.uk (Bill Karlsson)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Aug24.125948.1531@ox.ac.uk>
Date: Thu, 24 Aug 1995 12:59:48 GMT
References: <1995Aug21.185048.2452@panix.com> <1995Aug22.125548.2088@hanse.de>
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In article <1995Aug22.125548.2088@hanse.de>, avasiliev@hanse.de (Astrid Vasiliev) writes:
> Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.
> If you are posting from AOL, please read RFC 1036 before posting again.

Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in.

Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin!

-- 
Bill Karlsson -- Oxford University Computing Laboratory
"The hatch is open. Is anyone listening?"