From smacdonald@earthlink.net Wed Feb 08 07:29:33 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!earthlink!smacdonald From: smacdonald@earthlink.net (Steve MacDonald) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb08.072933.2600@earthlink.net> Date: Wed, 08 Feb 1995 07:29:33 GMT Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Steve MacDonald SupraFAXModem 28.8 @ ISDN 64k bps "5 sigma is a discovery. 7 is a question." From dpetrov@pacbell.net Fri Feb 10 04:06:33 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!pacbell!dpetrov From: dpetrov@pacbell.net (Diego Petrov) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb10.040633.7610@pacbell.net> Date: Fri, 10 Feb 1995 04:06:33 GMT References: <1995Feb08.072933.2600@earthlink.net> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Feb08.072933.2600@earthlink.net>, smacdonald@earthlink.net (Steve MacDonald) writes: > 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Diego Petrov -- Pacific Bell Internet Services "When every node is whole, the channel opens." From vtanaka@panix.com Sun Feb 12 04:11:33 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!panix!vtanaka From: vtanaka@panix.com (Valeria Tanaka) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb12.041133.1848@panix.com> Date: Sun, 12 Feb 1995 04:11:33 GMT References: <1995Feb08.072933.2600@earthlink.net> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Feb08.072933.2600@earthlink.net>, smacdonald@earthlink.net (Steve MacDonald) 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. If you are posting from AOL, please read RFC 1036 before posting again. -- Valeria Tanaka Tape trading list upon request. SASE required for international mail.