From mlopez@tum.de Thu Feb 23 01:57:10 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!tum!mlopez From: mlopez@tum.de (Mateo López) Newsgroups: comp.dsp Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb23.015710.9011@tum.de> Date: Thu, 23 Feb 1995 01:57:10 GMT Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: Netscape 1.1N 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. -- Mateo López Tape trading list upon request. SASE required for international mail. From vbrennan@unam.mx Thu Feb 23 04:44:10 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!unam!vbrennan From: vbrennan@unam.mx (Valeria Brennan) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb23.044410.9406@unam.mx> Date: Thu, 23 Feb 1995 04:44:10 GMT References: <1995Feb23.015710.9011@tum.de> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Feb23.015710.9011@tum.de>, mlopez@tum.de (Mateo López) 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. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Valeria Brennan *PLONK* filter active for trolls. Atari TT030 - NetBSD 1.0 From esouza@titech.ac.jp Fri Feb 24 09:21:10 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!titech!esouza From: esouza@titech.ac.jp (Elaine Souza) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb24.092110.9179@titech.ac.jp> Date: Fri, 24 Feb 1995 09:21:10 GMT References: <1995Feb23.015710.9011@tum.de> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Feb23.015710.9011@tum.de>, mlopez@tum.de (Mateo López) 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Elaine Souza Opinions expressed are solely my own and not those of Tokyo Institute of Technology Computer Centre. ------------------------------------------------------------ From gnovak@utexas.edu Fri Feb 24 23:13:10 1995 Path: ashpoly!cascade!mxgate!coyoacan!utexas!gnovak From: gnovak@utexas.edu (Göran Novak) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Feb24.231310.1043@utexas.edu> Date: Fri, 24 Feb 1995 23:13:10 GMT References: <1995Feb23.015710.9011@tum.de> <1995Feb23.044410.9406@unam.mx> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Feb23.044410.9406@unam.mx>, vbrennan@unam.mx (Valeria Brennan) 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. -- Göran Novak "Hold for relay." Commodore Amiga 500 (1MB OCS) / Linux 1.2.13