From mlopez@kiae.su Wed Feb 09 11:22:55 1994 Path: ashpoly!cascade!brgate!saturno!kiae!mlopez From: mlopez@kiae.su (Morag López) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb09.112255.3899@kiae.su> Date: Wed, 09 Feb 1994 11:22:55 GMT Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. 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. -- Morag López *PLONK* filter active for trolls. Decstation 5000/200 - NetBSD 1.0 From msantos@titech.ac.jp Wed Feb 09 12:26:55 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!titech!msantos From: msantos@titech.ac.jp (Mei Santos) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb09.122655.8997@titech.ac.jp> Date: Wed, 09 Feb 1994 12:26:55 GMT References: <1994Feb09.112255.3899@kiae.su> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: Netscape 1.1N Lines: 12 In article <1994Feb09.112255.3899@kiae.su>, mlopez@kiae.su (Morag López) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Mei Santos Practical Peripherals 14.4 @ 28,800 bps "When every node is whole, the channel opens." From kkim@unam.mx Fri Feb 11 04:03:55 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!unam!kkim From: kkim@unam.mx (Katrin Kim) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb11.040355.5928@unam.mx> Date: Fri, 11 Feb 1994 04:03:55 GMT References: <1994Feb09.112255.3899@kiae.su> <1994Feb09.122655.8997@titech.ac.jp> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1994Feb09.122655.8997@titech.ac.jp>, msantos@titech.ac.jp (Mei Santos) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! > My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- === Katrin Kim === Dept of Electrical Engineering, Universidad Nacional Autónoma de México (DGSCA) "Measuring a record you own is listening, not piracy." From alopez@tum.de Sun Feb 13 02:21:55 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!tum!alopez From: alopez@tum.de (Anton López) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb13.022155.2423@tum.de> Date: Sun, 13 Feb 1994 02:21:55 GMT References: <1994Feb09.112255.3899@kiae.su> <1994Feb09.122655.8997@titech.ac.jp> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Feb09.122655.8997@titech.ac.jp>, msantos@titech.ac.jp (Mei Santos) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! > My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Anton López *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From tduarte@mindspring.com Mon Feb 14 20:43:55 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!mindspring!tduarte From: tduarte@mindspring.com (Tobias Duarte) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Feb14.204355.5439@mindspring.com> Date: Mon, 14 Feb 1994 20:43:55 GMT References: <1994Feb09.112255.3899@kiae.su> <1994Feb09.122655.8997@titech.ac.jp> <1994Feb11.040355.5928@unam.mx> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Feb11.040355.5928@unam.mx>, kkim@unam.mx (Katrin Kim) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! > Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Tobias Duarte SupraFAXModem 28.8 @ ISDN 64k bps "Hold for relay."