From sjohansson@mindspring.com Mon Nov 06 09:18:05 1995 Path: ashpoly!cascade!mxgate!coyoacan!mindspring!sjohansson From: sjohansson@mindspring.com (Sun-mi Johansson) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov06.091805.3949@mindspring.com> Date: Mon, 06 Nov 1995 09:18:05 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: TIN [version 1.2 PL2] Lines: 11 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. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Sun-mi Johansson US Robotics Courier V.34 @ 9600 Telebit bps "When every node is whole, the channel opens." From hbrennan@titech.ac.jp Tue Nov 07 08:04:05 1995 Path: ashpoly!cascade!bigsur!titech!hbrennan From: hbrennan@titech.ac.jp (Hugo Brennan) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov07.080405.4811@titech.ac.jp> Date: Tue, 07 Nov 1995 08:04:05 GMT References: <1995Nov06.091805.3949@mindspring.com> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Nov06.091805.3949@mindspring.com>, sjohansson@mindspring.com (Sun-mi Johansson) 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- === Hugo Brennan === Dept of Electrical Engineering, Tokyo Institute of Technology Computer Centre "We don't sign stars. We build them." From jschneider@inria.fr Wed Nov 08 21:53:05 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!inria!jschneider From: jschneider@inria.fr (Ji-woo Schneider) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov08.215305.1005@inria.fr> Date: Wed, 08 Nov 1995 21:53:05 GMT References: <1995Nov06.091805.3949@mindspring.com> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Nov06.091805.3949@mindspring.com>, sjohansson@mindspring.com (Sun-mi Johansson) 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. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- === Ji-woo Schneider === Dept of Electrical Engineering, INRIA Rocquencourt "In theory there is no difference between theory and practice." From btanaka@uni-hamburg.de Thu Nov 09 13:51:05 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!uni-hamburg!btanaka From: btanaka@uni-hamburg.de (Bruno Tanaka) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov09.135105.6782@uni-hamburg.de> Date: Thu, 09 Nov 1995 13:51:05 GMT References: <1995Nov06.091805.3949@mindspring.com> <1995Nov08.215305.1005@inria.fr> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Nov08.215305.1005@inria.fr>, jschneider@inria.fr (Ji-woo Schneider) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Bruno Tanaka *PLONK* filter active for trolls. Amiga 1200 (Blizzard 030/50) - NetBSD 1.0