From asuzuki@cern.ch Thu Feb 24 18:15:06 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!cern!asuzuki From: asuzuki@cern.ch (Anton Suzuki) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb24.181506.9402@cern.ch> Date: Thu, 24 Feb 1994 18:15:06 GMT Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: WinVN 0.99.5 Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. 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. -- Anton Suzuki *PLONK* filter active for trolls. Atari Falcon 030 - NetBSD 1.0 From bsokolov@titech.ac.jp Sat Feb 26 09:24:06 1994 Path: ashpoly!cascade!transat!ukc!fennimore!titech!bsokolov From: bsokolov@titech.ac.jp (Brian Sokolov) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb26.092406.4481@titech.ac.jp> Date: Sat, 26 Feb 1994 09:24:06 GMT References: <1994Feb24.181506.9402@cern.ch> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Feb24.181506.9402@cern.ch>, asuzuki@cern.ch (Anton Suzuki) 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. -- Brian Sokolov Opinions expressed are solely my own and not those of Tokyo Institute of Technology Computer Centre. ------------------------------------------------------------ From kdubois@delphi.com Sun Feb 27 14:33:06 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!delphi!kdubois From: kdubois@delphi.com (Katrin Dubois) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb27.143306.1585@delphi.com> Date: Sun, 27 Feb 1994 14:33:06 GMT References: <1994Feb24.181506.9402@cern.ch> <1994Feb26.092406.4481@titech.ac.jp> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Feb26.092406.4481@titech.ac.jp>, bsokolov@titech.ac.jp (Brian Sokolov) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Katrin Dubois *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0 From srobertson@mindspring.com Tue Mar 01 02:52:06 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!mindspring!srobertson From: srobertson@mindspring.com (Seo-yeon Robertson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar01.025206.9669@mindspring.com> Date: Tue, 01 Mar 1994 02:52:06 GMT References: <1994Feb24.181506.9402@cern.ch> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: Netscape 1.1N Lines: 8 In article <1994Feb24.181506.9402@cern.ch>, asuzuki@cern.ch (Anton Suzuki) 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. -- Seo-yeon Robertson -- MindSpring Enterprises "In theory there is no difference between theory and practice." From mtakahashi@stanford.edu Tue Mar 01 12:11:06 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!stanford!mtakahashi From: mtakahashi@stanford.edu (Min-jun Takahashi) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar01.121106.5468@stanford.edu> Date: Tue, 01 Mar 1994 12:11:06 GMT References: <1994Feb24.181506.9402@cern.ch> <1994Feb26.092406.4481@titech.ac.jp> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Feb26.092406.4481@titech.ac.jp>, bsokolov@titech.ac.jp (Brian Sokolov) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Min-jun Takahashi | mtakahashi@stanford.edu PGP Key fingerprint: F24C 82C2 684A 6792 "Keep the channels open."