From akim@mindspring.com Thu Oct 06 10:09:59 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!mindspring!akim From: akim@mindspring.com (Astrid Kim) Newsgroups: comp.dsp Subject: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct06.100959.9903@mindspring.com> Date: Thu, 06 Oct 1994 10:09:59 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Astrid Kim Opinions expressed are solely my own and not those of MindSpring Enterprises. ------------------------------------------------------------ From hbrennan@clari.net Sat Oct 08 06:16:59 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!clari!hbrennan From: hbrennan@clari.net (Hugo Brennan) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct08.061659.6715@clari.net> Date: Sat, 08 Oct 1994 06:16:59 GMT References: <1994Oct06.100959.9903@mindspring.com> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Oct06.100959.9903@mindspring.com>, akim@mindspring.com (Astrid Kim) 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. -- Hugo Brennan "The hatch is open. Is anyone listening?" PC-9821Ap2 (NEC) / NEXTSTEP 3.3