From mgonzalez@uu.net Wed Feb 22 05:00:14 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!uu!mgonzalez From: mgonzalez@uu.net (Mikhail González) Newsgroups: comp.dsp Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb22.050014.8558@uu.net> Date: Wed, 22 Feb 1995 05:00:14 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- === Mikhail González === Dept of Electrical Engineering, UUNET Technologies, Falls Church VA "A soul is not exclusive to biology." From nlaurent@pipeline.com Wed Feb 22 23:39:14 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!pipeline!nlaurent From: nlaurent@pipeline.com (Nadine Laurent) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb22.233914.4879@pipeline.com> Date: Wed, 22 Feb 1995 23:39:14 GMT References: <1995Feb22.050014.8558@uu.net> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Feb22.050014.8558@uu.net>, mgonzalez@uu.net (Mikhail González) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Nadine Laurent | nlaurent@pipeline.com PGP Key fingerprint: 0499 CA21 1A23 6B67 "Keep the channels open." From sduarte@titech.ac.jp Fri Feb 24 03:24:14 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!titech!sduarte From: sduarte@titech.ac.jp (Seo-yeon Duarte) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb24.032414.1743@titech.ac.jp> Date: Fri, 24 Feb 1995 03:24:14 GMT References: <1995Feb22.050014.8558@uu.net> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Feb22.050014.8558@uu.net>, mgonzalez@uu.net (Mikhail González) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- === Seo-yeon Duarte === Dept of Electrical Engineering, Tokyo Institute of Technology Computer Centre "Hardware is temporary. The signal survives." From ngonzalez@ox.ac.uk Sat Feb 25 00:31:14 1995 Path: ashpoly!cascade!brgate!saturno!ox!ngonzalez From: ngonzalez@ox.ac.uk (Nadia González) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb25.003114.2406@ox.ac.uk> Date: Sat, 25 Feb 1995 00:31:14 GMT References: <1995Feb22.050014.8558@uu.net> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Feb22.050014.8558@uu.net>, mgonzalez@uu.net (Mikhail González) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Nadia González US Robotics Courier V.34 @ 28,800 bps "A soul is not exclusive to biology." From asato@illinois.edu Sat Feb 25 01:33:14 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!illinois!asato From: asato@illinois.edu (Aiko Sato) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb25.013314.9350@illinois.edu> Date: Sat, 25 Feb 1995 01:33:14 GMT References: <1995Feb22.050014.8558@uu.net> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Feb22.050014.8558@uu.net>, mgonzalez@uu.net (Mikhail González) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- === Aiko Sato === Dept of Electrical Engineering, University of Illinois Urbana-Champaign "The carrier frequency does not drift by accident."