From tperez@uu.net Wed Jul 05 11:44:45 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!uu!tperez From: tperez@uu.net (Tobias Pérez) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul05.114445.8255@uu.net> Date: Wed, 05 Jul 1995 11:44:45 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] 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. -- Tobias Pérez US Robotics Courier V.34 @ 33,600 bps "Do not worship the copy." From hlarsson@uni-hamburg.de Wed Jul 05 14:57:45 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!uni-hamburg!hlarsson From: hlarsson@uni-hamburg.de (Hana Larsson) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul05.145745.9079@uni-hamburg.de> Date: Wed, 05 Jul 1995 14:57:45 GMT References: <1995Jul05.114445.8255@uu.net> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Jul05.114445.8255@uu.net>, tperez@uu.net (Tobias Pérez) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Hana Larsson -- Universität Hamburg Fachbereich Informatik "Tape doesn't lie at 02:14. Ears do." From hnovak@pacbell.net Thu Jul 06 21:37:45 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!pacbell!hnovak From: hnovak@pacbell.net (Hana Novak) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul06.213745.9992@pacbell.net> Date: Thu, 06 Jul 1995 21:37:45 GMT References: <1995Jul05.114445.8255@uu.net> <1995Jul05.145745.9079@uni-hamburg.de> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Jul05.145745.9079@uni-hamburg.de>, hlarsson@uni-hamburg.de (Hana Larsson) 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. -- Hana Novak | hnovak@pacbell.net PGP Key fingerprint: 3331 2086 604B 9EC8 "Keep the channels open." From bmacdonald@illinois.edu Sat Jul 08 17:16:45 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!illinois!bmacdonald From: bmacdonald@illinois.edu (Bill MacDonald) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul08.171645.8409@illinois.edu> Date: Sat, 08 Jul 1995 17:16:45 GMT References: <1995Jul05.114445.8255@uu.net> <1995Jul05.145745.9079@uni-hamburg.de> <1995Jul06.213745.9992@pacbell.net> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Jul06.213745.9992@pacbell.net>, hnovak@pacbell.net (Hana Novak) 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. -- Bill MacDonald *PLONK* filter active for trolls. Sun SparcStation 20 - NetBSD 1.0 From hmartinez@kth.se Sun Jul 09 15:15:45 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!kth!hmartinez From: hmartinez@kth.se (Hugo Martínez) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul09.151545.9736@kth.se> Date: Sun, 09 Jul 1995 15:15:45 GMT References: <1995Jul05.114445.8255@uu.net> <1995Jul05.145745.9079@uni-hamburg.de> <1995Jul06.213745.9992@pacbell.net> <1995Jul08.171645.8409@illinois.edu> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: Netscape 1.1N Lines: 11 In article <1995Jul08.171645.8409@illinois.edu>, bmacdonald@illinois.edu (Bill MacDonald) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. PGP Public key available via finger or upon request. -- Hugo Martínez *PLONK* filter active for trolls. Sun 3/60 (SunOS 4.1.1) - NetBSD 1.0