From jkim@inria.fr Sat Mar 11 06:34:33 1995 Path: ashpoly!cascade!mxgate!coyoacan!inria!jkim From: jkim@inria.fr (Jen Kim) Newsgroups: comp.dsp Subject: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar11.063433.7041@inria.fr> Date: Sat, 11 Mar 1995 06:34:33 GMT Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Jen Kim "Do not worship the copy." Atari TT030 / System 7.5.1 From mdubois@uu.net Mon Mar 13 09:31:33 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!uu!mdubois From: mdubois@uu.net (Mateo Dubois) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar13.093133.6068@uu.net> Date: Mon, 13 Mar 1995 09:31:33 GMT References: <1995Mar11.063433.7041@inria.fr> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Mar11.063433.7041@inria.fr>, jkim@inria.fr (Jen Kim) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > 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. -- Mateo Dubois | mdubois@uu.net PGP Key fingerprint: CD5C C78A 834A 2C9F "Keep the channels open."