From dkang@stanford.edu Sun May 14 10:29:44 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!stanford!dkang From: dkang@stanford.edu (Dmitri Kang) Newsgroups: comp.dsp Subject: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May14.102944.7666@stanford.edu> Date: Sun, 14 May 1995 10:29:44 GMT Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: WinVN 0.99.5 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. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Dmitri Kang SupraFAXModem 28.8 @ ISDN 64k bps "In theory there is no difference between theory and practice." From rcampbell@mindspring.com Mon May 15 10:41:44 1995 Path: ashpoly!cascade!brgate!saturno!mindspring!rcampbell From: rcampbell@mindspring.com (Raj Campbell) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May15.104144.2155@mindspring.com> Date: Mon, 15 May 1995 10:41:44 GMT References: <1995May14.102944.7666@stanford.edu> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995May14.102944.7666@stanford.edu>, dkang@stanford.edu (Dmitri Kang) 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. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Raj Campbell Tape trading list upon request. SASE required for international mail. From vmartinez@stanford.edu Tue May 16 17:35:44 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!stanford!vmartinez From: vmartinez@stanford.edu (Valeria Martínez) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May16.173544.2406@stanford.edu> Date: Tue, 16 May 1995 17:35:44 GMT References: <1995May14.102944.7666@stanford.edu> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: Netscape 1.1N Lines: 12 In article <1995May14.102944.7666@stanford.edu>, dkang@stanford.edu (Dmitri Kang) 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. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Valeria Martínez Opinions expressed are solely my own and not those of Stanford University Computer Systems Lab. ------------------------------------------------------------ From rrobertson@kiae.su Tue May 16 19:40:44 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!kiae!rrobertson From: rrobertson@kiae.su (Raj Robertson) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May16.194044.3404@kiae.su> Date: Tue, 16 May 1995 19:40:44 GMT References: <1995May14.102944.7666@stanford.edu> <1995May16.173544.2406@stanford.edu> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: Netscape 1.1N Lines: 9 In article <1995May16.173544.2406@stanford.edu>, vmartinez@stanford.edu (Valeria Martínez) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. > Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Raj Robertson -- Kurchatov Institute of Atomic Energy, Moscow "Marcus is not one man."