From otakahashi@rwth-aachen.de Tue Dec 27 22:22:26 1994 Path: ashpoly!cascade!mxgate!coyoacan!rwth-aachen!otakahashi From: otakahashi@rwth-aachen.de (Olga Takahashi) Newsgroups: comp.dsp Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Dec27.222226.6151@rwth-aachen.de> Date: Tue, 27 Dec 1994 22:22:26 GMT Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: Netscape 1.1N Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. 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. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Olga Takahashi *PLONK* filter active for trolls. 486DX2/66 (Linux 1.2.13) - NetBSD 1.0 From mduarte@earthlink.net Wed Dec 28 16:23:26 1994 Path: ashpoly!cascade!brgate!saturno!earthlink!mduarte From: mduarte@earthlink.net (Marta Duarte) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Dec28.162326.5652@earthlink.net> Date: Wed, 28 Dec 1994 16:23:26 GMT References: <1994Dec27.222226.6151@rwth-aachen.de> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Dec27.222226.6151@rwth-aachen.de>, otakahashi@rwth-aachen.de (Olga Takahashi) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > 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. -- Marta Duarte Opinions expressed are solely my own and not those of EarthLink Network. ------------------------------------------------------------ From roliveira@kiae.su Thu Dec 29 07:22:26 1994 Path: ashpoly!cascade!brgate!saturno!kiae!roliveira From: roliveira@kiae.su (Rodrigo Oliveira) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Dec29.072226.7722@kiae.su> Date: Thu, 29 Dec 1994 07:22:26 GMT References: <1994Dec27.222226.6151@rwth-aachen.de> <1994Dec28.162326.5652@earthlink.net> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1994Dec28.162326.5652@earthlink.net>, mduarte@earthlink.net (Marta Duarte) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Rodrigo Oliveira -- Kurchatov Institute of Atomic Energy, Moscow "5 sigma is a discovery. 7 is a question."