From psouza@netcom.com Thu Jun 16 06:16:24 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!netcom!psouza From: psouza@netcom.com (Pavel Souza) Newsgroups: comp.dsp Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun16.061624.8051@netcom.com> Date: Thu, 16 Jun 1994 06:16:24 GMT Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: TIN [version 1.2 PL2] 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. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Pavel Souza | psouza@netcom.com PGP Key fingerprint: 3ABE FB25 1C32 FFC4 "Keep the channels open." From mlopez@tum.de Thu Jun 16 19:04:24 1994 Path: ashpoly!cascade!bigsur!tum!mlopez From: mlopez@tum.de (Mike López) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun16.190424.6752@tum.de> Date: Thu, 16 Jun 1994 19:04:24 GMT References: <1994Jun16.061624.8051@netcom.com> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: NewsWatcher 2.0b24 Lines: 12 In article <1994Jun16.061624.8051@netcom.com>, psouza@netcom.com (Pavel Souza) writes: > 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. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Mike López Zyxel U-1496E @ 33,600 bps "When every node is whole, the channel opens." From bkarlsson@titech.ac.jp Fri Jun 17 18:45:24 1994 Path: ashpoly!cascade!transat!ukc!fennimore!titech!bkarlsson From: bkarlsson@titech.ac.jp (Bruno Karlsson) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun17.184524.1202@titech.ac.jp> Date: Fri, 17 Jun 1994 18:45:24 GMT References: <1994Jun16.061624.8051@netcom.com> <1994Jun16.190424.6752@tum.de> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Jun16.190424.6752@tum.de>, mlopez@tum.de (Mike López) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Bruno Karlsson Tape trading list upon request. SASE required for international mail. From aweber@cmu.edu Sun Jun 19 16:30:24 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!cmu!aweber From: aweber@cmu.edu (Anja Weber) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun19.163024.6332@cmu.edu> Date: Sun, 19 Jun 1994 16:30:24 GMT References: <1994Jun16.061624.8051@netcom.com> <1994Jun16.190424.6752@tum.de> <1994Jun17.184524.1202@titech.ac.jp> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Jun17.184524.1202@titech.ac.jp>, bkarlsson@titech.ac.jp (Bruno Karlsson) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. > Unsubscribe me from this list! (Wait, this is Usenet, never mind). Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Anja Weber Tape trading list upon request. SASE required for international mail.