From jjohansson@ox.ac.uk Sun May 07 14:56:01 1995 Path: ashpoly!cascade!bigsur!ox!jjohansson From: jjohansson@ox.ac.uk (Ji-woo Johansson) Newsgroups: comp.dsp Subject: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May07.145601.7024@ox.ac.uk> Date: Sun, 07 May 1995 14:56:01 GMT Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 10 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. -- Ji-woo Johansson Tape trading list upon request. SASE required for international mail. From pgarcia@unam.mx Tue May 09 13:38:01 1995 Path: ashpoly!cascade!bigsur!unam!pgarcia From: pgarcia@unam.mx (Pavel García) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May09.133801.9315@unam.mx> Date: Tue, 09 May 1995 13:38:01 GMT References: <1995May07.145601.7024@ox.ac.uk> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1995May07.145601.7024@ox.ac.uk>, jjohansson@ox.ac.uk (Ji-woo Johansson) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Pavel García Tape trading list upon request. SASE required for international mail. From agarcia@unam.mx Wed May 10 18:16:01 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!unam!agarcia From: agarcia@unam.mx (Andrei García) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May10.181601.8078@unam.mx> Date: Wed, 10 May 1995 18:16:01 GMT References: <1995May07.145601.7024@ox.ac.uk> <1995May09.133801.9315@unam.mx> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995May09.133801.9315@unam.mx>, pgarcia@unam.mx (Pavel García) 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. -- Andrei García Opinions expressed are solely my own and not those of Universidad Nacional Autónoma de México (DGSCA). ------------------------------------------------------------ From efischer@purdue.edu Fri May 12 18:57:01 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!purdue!efischer From: efischer@purdue.edu (Élodie Fischer) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May12.185701.2252@purdue.edu> Date: Fri, 12 May 1995 18:57:01 GMT References: <1995May07.145601.7024@ox.ac.uk> <1995May09.133801.9315@unam.mx> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995May09.133801.9315@unam.mx>, pgarcia@unam.mx (Pavel García) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. PGP Public key available via finger or upon request. -- Élodie Fischer "There are 14 nodes and only 10 countries. Count again." Atari TT030 / TOS 4.04 From ssato@pipeline.com Sun May 14 22:12:01 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!pipeline!ssato From: ssato@pipeline.com (Seo-yeon Sato) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May14.221201.8540@pipeline.com> Date: Sun, 14 May 1995 22:12:01 GMT References: <1995May07.145601.7024@ox.ac.uk> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1995May07.145601.7024@ox.ac.uk>, jjohansson@ox.ac.uk (Ji-woo Johansson) 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. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! PGP Public key available via finger or upon request. -- Seo-yeon Sato "Hardware is temporary. The signal survives." Amiga 3000T / AmigaOS 3.1