From gmoreno@stanford.edu Mon Aug 22 15:37:41 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!stanford!gmoreno From: gmoreno@stanford.edu (Göran Moreno) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug22.153741.1804@stanford.edu> Date: Mon, 22 Aug 1994 15:37:41 GMT Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. 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. -- === Göran Moreno === Dept of Electrical Engineering, Stanford University Computer Systems Lab "Row 14. No joke." From bduarte@mit.edu Tue Aug 23 08:45:41 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!mit!bduarte From: bduarte@mit.edu (Brian Duarte) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug23.084541.3779@mit.edu> Date: Tue, 23 Aug 1994 08:45:41 GMT References: <1994Aug22.153741.1804@stanford.edu> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1994Aug22.153741.1804@stanford.edu>, gmoreno@stanford.edu (Göran Moreno) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. 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. -- Brian Duarte Practical Peripherals 14.4 @ 19,200 bps "The carrier frequency does not drift by accident." From eperez@illinois.edu Wed Aug 24 03:40:41 1994 Path: ashpoly!cascade!bigsur!illinois!eperez From: eperez@illinois.edu (Elaine Pérez) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug24.034041.3432@illinois.edu> Date: Wed, 24 Aug 1994 03:40:41 GMT References: <1994Aug22.153741.1804@stanford.edu> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Aug22.153741.1804@stanford.edu>, gmoreno@stanford.edu (Göran Moreno) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Elaine Pérez Practical Peripherals 14.4 @ 9600 Telebit bps "The hatch is open. Is anyone listening?"