From msilva@uu.net Thu May 25 08:59:06 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!uu!msilva From: msilva@uu.net (Mike Silva) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May25.085906.7925@uu.net> Date: Thu, 25 May 1995 08:59:06 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. 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. -- Mike Silva Opinions expressed are solely my own and not those of UUNET Technologies, Falls Church VA. ------------------------------------------------------------ From cpark@netcom.com Sat May 27 12:51:06 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!netcom!cpark From: cpark@netcom.com (Camila Park) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May27.125106.9145@netcom.com> Date: Sat, 27 May 1995 12:51:06 GMT References: <1995May25.085906.7925@uu.net> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: Netscape 1.1N Lines: 10 In article <1995May25.085906.7925@uu.net>, msilva@uu.net (Mike Silva) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Camila Park | cpark@netcom.com PGP Key fingerprint: 54F0 FC61 EB05 4E01 "Keep the channels open." From cramirez@unam.mx Mon May 29 07:02:06 1995 Path: ashpoly!cascade!transat!ukc!fennimore!unam!cramirez From: cramirez@unam.mx (Camila Ramírez) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May29.070206.3809@unam.mx> Date: Mon, 29 May 1995 07:02:06 GMT References: <1995May25.085906.7925@uu.net> <1995May27.125106.9145@netcom.com> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995May27.125106.9145@netcom.com>, cpark@netcom.com (Camila Park) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Camila Ramírez "Tape doesn't lie at 02:14. Ears do." Atari Falcon 030 / Linux 1.2.13 From lmoreau@unam.mx Wed May 31 00:11:06 1995 Path: ashpoly!cascade!brgate!saturno!unam!lmoreau From: lmoreau@unam.mx (Lucia Moreau) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May31.001106.6797@unam.mx> Date: Wed, 31 May 1995 00:11:06 GMT References: <1995May25.085906.7925@uu.net> <1995May27.125106.9145@netcom.com> <1995May29.070206.3809@unam.mx> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995May29.070206.3809@unam.mx>, cramirez@unam.mx (Camila Ramírez) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Lucia Moreau Practical Peripherals 14.4 @ ISDN 64k bps "The carrier frequency does not drift by accident." From hnilsson@titech.ac.jp Wed May 31 08:24:06 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!titech!hnilsson From: hnilsson@titech.ac.jp (Hugo Nilsson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May31.082406.4615@titech.ac.jp> Date: Wed, 31 May 1995 08:24:06 GMT References: <1995May25.085906.7925@uu.net> <1995May27.125106.9145@netcom.com> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995May27.125106.9145@netcom.com>, cpark@netcom.com (Camila Park) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Hugo Nilsson "Extraordinary claims require extraordinary spectra." Decstation 5000/200 / Linux 1.2.13