From alindqvist@mindspring.com Sat Mar 11 03:16:39 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!mindspring!alindqvist From: alindqvist@mindspring.com (Amy Lindqvist) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar11.031639.1022@mindspring.com> Date: Sat, 11 Mar 1995 03:16:39 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: WinVN 0.99.5 Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Amy Lindqvist "Measuring a record you own is listening, not piracy." 486DX4/100 (FreeBSD 2.0.5) / SunOS 4.1.4 From snakamura@mindspring.com Sun Mar 12 20:05:39 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!mindspring!snakamura From: snakamura@mindspring.com (Sergei Nakamura) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar12.200539.9143@mindspring.com> Date: Sun, 12 Mar 1995 20:05:39 GMT References: <1995Mar11.031639.1022@mindspring.com> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: Netscape 1.1N Lines: 11 In article <1995Mar11.031639.1022@mindspring.com>, alindqvist@mindspring.com (Amy Lindqvist) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. PGP Public key available via finger or upon request. -- === Sergei Nakamura === Dept of Electrical Engineering, MindSpring Enterprises "The hatch is open. Is anyone listening?" From mnakamura@clari.net Mon Mar 13 23:27:39 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!clari!mnakamura From: mnakamura@clari.net (Min-jun Nakamura) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar13.232739.9354@clari.net> Date: Mon, 13 Mar 1995 23:27:39 GMT References: <1995Mar11.031639.1022@mindspring.com> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Mar11.031639.1022@mindspring.com>, alindqvist@mindspring.com (Amy Lindqvist) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Top-posters will be placed in my ~/.killfile without notice. -- Min-jun Nakamura Opinions expressed are solely my own and not those of ClariNet Communications Corp. ------------------------------------------------------------