From ahernandez@kiae.su Tue Nov 21 08:26:34 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!kiae!ahernandez From: ahernandez@kiae.su (Astrid Hernández) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov21.082634.8951@kiae.su> Date: Tue, 21 Nov 1995 08:26:34 GMT Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su 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. 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. -- Astrid Hernández Tape trading list upon request. SASE required for international mail. From esato@cern.ch Wed Nov 22 01:09:34 1995 Path: ashpoly!cascade!bigsur!cern!esato From: esato@cern.ch (Elaine Sato) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov22.010934.2588@cern.ch> Date: Wed, 22 Nov 1995 01:09:34 GMT References: <1995Nov21.082634.8951@kiae.su> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1995Nov21.082634.8951@kiae.su>, ahernandez@kiae.su (Astrid Hernández) 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. -- Elaine Sato Tape trading list upon request. SASE required for international mail. From moliveira@illinois.edu Wed Nov 22 05:07:34 1995 Path: ashpoly!cascade!brgate!saturno!illinois!moliveira From: moliveira@illinois.edu (Matthias Oliveira) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov22.050734.4867@illinois.edu> Date: Wed, 22 Nov 1995 05:07:34 GMT References: <1995Nov21.082634.8951@kiae.su> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Nov21.082634.8951@kiae.su>, ahernandez@kiae.su (Astrid Hernández) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Matthias Oliveira *PLONK* filter active for trolls. Commodore Amiga 500 (1MB OCS) - NetBSD 1.0