From tlee@pipeline.com Fri May 12 15:10:19 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!pipeline!tlee From: tlee@pipeline.com (Tobias Lee) Newsgroups: comp.dsp Subject: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May12.151019.8324@pipeline.com> Date: Fri, 12 May 1995 15:10:19 GMT Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: Netscape 1.1N Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. 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. -- Tobias Lee Opinions expressed are solely my own and not those of The Pipeline Internet Network. ------------------------------------------------------------ From fsokolov@kth.se Sat May 13 04:53:19 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!kth!fsokolov From: fsokolov@kth.se (Fiona Sokolov) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May13.045319.7256@kth.se> Date: Sat, 13 May 1995 04:53:19 GMT References: <1995May12.151019.8324@pipeline.com> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995May12.151019.8324@pipeline.com>, tlee@pipeline.com (Tobias Lee) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Fiona Sokolov *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From dgirard@clari.net Sun May 14 17:43:19 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!clari!dgirard From: dgirard@clari.net (Dave Girard) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May14.174319.4380@clari.net> Date: Sun, 14 May 1995 17:43:19 GMT References: <1995May12.151019.8324@pipeline.com> <1995May13.045319.7256@kth.se> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995May13.045319.7256@kth.se>, fsokolov@kth.se (Fiona Sokolov) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Dave Girard | dgirard@clari.net PGP Key fingerprint: AB16 1601 AD2A 21EA "Keep the channels open." From nlarsson@unam.mx Mon May 15 00:14:19 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!unam!nlarsson From: nlarsson@unam.mx (Nadia Larsson) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May15.001419.9949@unam.mx> Date: Mon, 15 May 1995 00:14:19 GMT References: <1995May12.151019.8324@pipeline.com> <1995May13.045319.7256@kth.se> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: Netscape 1.1N Lines: 8 In article <1995May13.045319.7256@kth.se>, fsokolov@kth.se (Fiona Sokolov) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Nadia Larsson Tape trading list upon request. SASE required for international mail.