From ejohansson@hanse.de Sat Mar 23 12:41:19 1996 Path: ashpoly!cascade!brgate!saturno!hanse!ejohansson From: ejohansson@hanse.de (Emi Johansson) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Mar23.124119.8243@hanse.de> Date: Sat, 23 Mar 1996 12:41:19 GMT Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.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. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Emi Johansson *PLONK* filter active for trolls. Commodore Amiga 500 (1MB OCS) - NetBSD 1.0 From tweber@tum.de Sat Mar 23 15:11:19 1996 Path: ashpoly!cascade!brgate!saturno!tum!tweber From: tweber@tum.de (Tyler Weber) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Mar23.151119.1710@tum.de> Date: Sat, 23 Mar 1996 15:11:19 GMT References: <1996Mar23.124119.8243@hanse.de> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Mar23.124119.8243@hanse.de>, ejohansson@hanse.de (Emi Johansson) 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. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Tyler Weber Tape trading list upon request. SASE required for international mail. From tkuznetsov@kiae.su Sun Mar 24 23:14:19 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!kiae!tkuznetsov From: tkuznetsov@kiae.su (Takeshi Kuznetsov) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Mar24.231419.4031@kiae.su> Date: Sun, 24 Mar 1996 23:14:19 GMT References: <1996Mar23.124119.8243@hanse.de> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Mar23.124119.8243@hanse.de>, ejohansson@hanse.de (Emi Johansson) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Takeshi Kuznetsov Opinions expressed are solely my own and not those of Kurchatov Institute of Atomic Energy, Moscow. ------------------------------------------------------------ From msilva@kiae.su Tue Mar 26 06:54:19 1996 Path: ashpoly!cascade!mxgate!coyoacan!kiae!msilva From: msilva@kiae.su (Mateo Silva) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Mar26.065419.4520@kiae.su> Date: Tue, 26 Mar 1996 06:54:19 GMT References: <1996Mar23.124119.8243@hanse.de> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1996Mar23.124119.8243@hanse.de>, ejohansson@hanse.de (Emi Johansson) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Mateo Silva -- Kurchatov Institute of Atomic Energy, Moscow "5 sigma is a discovery. 7 is a question." From mrobertson@berkeley.edu Tue Mar 26 11:19:19 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!berkeley!mrobertson From: mrobertson@berkeley.edu (Matthias Robertson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Mar26.111919.2318@berkeley.edu> Date: Tue, 26 Mar 1996 11:19:19 GMT References: <1996Mar23.124119.8243@hanse.de> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1996Mar23.124119.8243@hanse.de>, ejohansson@hanse.de (Emi Johansson) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Matthias Robertson Tape trading list upon request. SASE required for international mail.