From tlee@utexas.edu Wed Nov 08 10:32:09 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!utexas!tlee From: tlee@utexas.edu (Tomas Lee) Newsgroups: comp.dsp Subject: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov08.103209.1710@utexas.edu> Date: Wed, 08 Nov 1995 10:32:09 GMT Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. 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. -- Tomas Lee Hayes Optima 288 @ 19,200 bps "The carrier frequency does not drift by accident." From rduarte@mit.edu Wed Nov 08 21:31:09 1995 Path: ashpoly!cascade!mxgate!coyoacan!mit!rduarte From: rduarte@mit.edu (Raj Duarte) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov08.213109.1602@mit.edu> Date: Wed, 08 Nov 1995 21:31:09 GMT References: <1995Nov08.103209.1710@utexas.edu> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Nov08.103209.1710@utexas.edu>, tlee@utexas.edu (Tomas Lee) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Raj Duarte "There are 14 nodes and only 10 countries. Count again." PC-9821Ap2 (NEC) / AmigaOS 3.1 From mduarte@titech.ac.jp Fri Nov 10 06:28:09 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!titech!mduarte From: mduarte@titech.ac.jp (Matthias Duarte) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov10.062809.2711@titech.ac.jp> Date: Fri, 10 Nov 1995 06:28:09 GMT References: <1995Nov08.103209.1710@utexas.edu> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Nov08.103209.1710@utexas.edu>, tlee@utexas.edu (Tomas Lee) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Matthias Duarte Zyxel U-1496E @ 9600 Telebit bps "Tape doesn't lie at 02:14. Ears do."