From yweber@hanse.de Tue Apr 19 21:06:47 1994 Path: ashpoly!cascade!transat!ukc!fennimore!hanse!yweber From: yweber@hanse.de (Yuki Weber) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Apr19.210647.4628@hanse.de> Date: Tue, 19 Apr 1994 21:06:47 GMT Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Yuki Weber "Hardware is temporary. The signal survives." 486DX4/100 (FreeBSD 2.0.5) / SunOS 4.1.4 From rtakahashi@mit.edu Thu Apr 21 17:38:47 1994 Path: ashpoly!cascade!brgate!saturno!mit!rtakahashi From: rtakahashi@mit.edu (Raj Takahashi) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Apr21.173847.1224@mit.edu> Date: Thu, 21 Apr 1994 17:38:47 GMT References: <1994Apr19.210647.4628@hanse.de> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 12 In article <1994Apr19.210647.4628@hanse.de>, yweber@hanse.de (Yuki Weber) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > 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. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Raj Takahashi "We don't sign stars. We build them." NeXTstation Turbo Color / NEXTSTEP 3.3