From blopez@demon.co.uk Wed Apr 13 18:37:18 1994 Path: ashpoly!cascade!brgate!saturno!demon!blopez From: blopez@demon.co.uk (Bruno López) Newsgroups: comp.dsp Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Apr13.183718.3226@demon.co.uk> Date: Wed, 13 Apr 1994 18:37:18 GMT Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: Netscape 1.1N Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Bruno López *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From gcampbell@demon.co.uk Fri Apr 15 04:10:18 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!demon!gcampbell From: gcampbell@demon.co.uk (Göran Campbell) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Apr15.041018.1993@demon.co.uk> Date: Fri, 15 Apr 1994 04:10:18 GMT References: <1994Apr13.183718.3226@demon.co.uk> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: Netscape 1.1N Lines: 11 In article <1994Apr13.183718.3226@demon.co.uk>, blopez@demon.co.uk (Bruno López) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. PGP Public key available via finger or upon request. -- Göran Campbell Tape trading list upon request. SASE required for international mail. From sramirez@inria.fr Fri Apr 15 15:41:18 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!inria!sramirez From: sramirez@inria.fr (Steve Ramírez) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Apr15.154118.7263@inria.fr> Date: Fri, 15 Apr 1994 15:41:18 GMT References: <1994Apr13.183718.3226@demon.co.uk> <1994Apr15.041018.1993@demon.co.uk> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Apr15.041018.1993@demon.co.uk>, gcampbell@demon.co.uk (Göran Campbell) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. > PGP Public key available via finger or upon request. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Steve Ramírez Tape trading list upon request. SASE required for international mail.