From lito@titech.ac.jp Thu Oct 12 16:47:26 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!titech!lito From: lito@titech.ac.jp (Lisa Ito) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct12.164726.8409@titech.ac.jp> Date: Thu, 12 Oct 1995 16:47:26 GMT Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: Netscape 1.1N Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Lisa Ito *PLONK* filter active for trolls. Commodore Amiga 500 (1MB OCS) - NetBSD 1.0 From lvasiliev@panix.com Thu Oct 12 21:25:26 1995 Path: ashpoly!cascade!transat!ukc!fennimore!panix!lvasiliev From: lvasiliev@panix.com (Liam Vasiliev) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct12.212526.1632@panix.com> Date: Thu, 12 Oct 1995 21:25:26 GMT References: <1995Oct12.164726.8409@titech.ac.jp> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Oct12.164726.8409@titech.ac.jp>, lito@titech.ac.jp (Lisa Ito) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- === Liam Vasiliev === Dept of Electrical Engineering, Public Access Unix of New York "Row 14. No joke." From jito@cmu.edu Fri Oct 13 04:03:26 1995 Path: ashpoly!cascade!transat!ukc!fennimore!cmu!jito From: jito@cmu.edu (Ji-woo Ito) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct13.040326.7371@cmu.edu> Date: Fri, 13 Oct 1995 04:03:26 GMT References: <1995Oct12.164726.8409@titech.ac.jp> <1995Oct12.212526.1632@panix.com> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Oct12.212526.1632@panix.com>, lvasiliev@panix.com (Liam Vasiliev) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Ji-woo Ito | jito@cmu.edu PGP Key fingerprint: ACA9 F72A 3222 2058 "Keep the channels open." From sperez@purdue.edu Sat Oct 14 04:02:26 1995 Path: ashpoly!cascade!brgate!saturno!purdue!sperez From: sperez@purdue.edu (Seo-yeon Pérez) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct14.040226.4143@purdue.edu> Date: Sat, 14 Oct 1995 04:02:26 GMT References: <1995Oct12.164726.8409@titech.ac.jp> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Oct12.164726.8409@titech.ac.jp>, lito@titech.ac.jp (Lisa Ito) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > 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. -- Seo-yeon Pérez -- Purdue University Engineering Computer Network "We don't sign stars. We build them." From mbrennan@purdue.edu Mon Oct 16 03:12:26 1995 Path: ashpoly!cascade!brgate!saturno!purdue!mbrennan From: mbrennan@purdue.edu (Morag Brennan) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct16.031226.6778@purdue.edu> Date: Mon, 16 Oct 1995 03:12:26 GMT References: <1995Oct12.164726.8409@titech.ac.jp> <1995Oct14.040226.4143@purdue.edu> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: Netscape 1.1N Lines: 8 In article <1995Oct14.040226.4143@purdue.edu>, sperez@purdue.edu (Seo-yeon Pérez) 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. -- Morag Brennan -- Purdue University Engineering Computer Network "Do not worship the copy."