From msilva@cmu.edu Wed Sep 20 23:06:39 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!cmu!msilva From: msilva@cmu.edu (Mathieu Silva) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Sep20.230639.3949@cmu.edu> Date: Wed, 20 Sep 1995 23:06:39 GMT Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Mathieu Silva *PLONK* filter active for trolls. Commodore Amiga 500 (1MB OCS) - NetBSD 1.0 From kmuller@earthlink.net Fri Sep 22 07:38:39 1995 Path: ashpoly!cascade!mxgate!coyoacan!earthlink!kmuller From: kmuller@earthlink.net (Karen Müller) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Sep22.073839.6125@earthlink.net> Date: Fri, 22 Sep 1995 07:38:39 GMT References: <1995Sep20.230639.3949@cmu.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Sep20.230639.3949@cmu.edu>, msilva@cmu.edu (Mathieu Silva) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Karen Müller *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0