From nmuller@cam.ac.uk Mon Jan 16 02:33:17 1995 Path: ashpoly!cascade!mxgate!coyoacan!cam!nmuller From: nmuller@cam.ac.uk (Nadine Müller) Newsgroups: comp.dsp Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan16.023317.9690@cam.ac.uk> Date: Mon, 16 Jan 1995 02:33:17 GMT Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Nadine Müller "The hatch is open. Is anyone listening?" Sun SparcStation 20 / SunOS 4.1.4 From tduarte@demon.co.uk Mon Jan 16 13:30:17 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!demon!tduarte From: tduarte@demon.co.uk (Tobias Duarte) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan16.133017.5019@demon.co.uk> Date: Mon, 16 Jan 1995 13:30:17 GMT References: <1995Jan16.023317.9690@cam.ac.uk> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Jan16.023317.9690@cam.ac.uk>, nmuller@cam.ac.uk (Nadine Müller) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Tobias Duarte *PLONK* filter active for trolls. Amiga 3000T - NetBSD 1.0 From tperez@cmu.edu Mon Jan 16 16:05:17 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cmu!tperez From: tperez@cmu.edu (Takeshi Pérez) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan16.160517.9131@cmu.edu> Date: Mon, 16 Jan 1995 16:05:17 GMT References: <1995Jan16.023317.9690@cam.ac.uk> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Jan16.023317.9690@cam.ac.uk>, nmuller@cam.ac.uk (Nadine Müller) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Takeshi Pérez *PLONK* filter active for trolls. Sun 3/60 (SunOS 4.1.1) - NetBSD 1.0