From fsouza@mindspring.com Wed Aug 23 01:53:12 1995 Path: ashpoly!cascade!mxgate!coyoacan!mindspring!fsouza From: fsouza@mindspring.com (Freya Souza) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug23.015312.1172@mindspring.com> Date: Wed, 23 Aug 1995 01:53:12 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. 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. -- Freya Souza Tape trading list upon request. SASE required for international mail. From nsilva@tum.de Thu Aug 24 22:02:12 1995 Path: ashpoly!cascade!bigsur!tum!nsilva From: nsilva@tum.de (Natalia Silva) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug24.220212.5100@tum.de> Date: Thu, 24 Aug 1995 22:02:12 GMT References: <1995Aug23.015312.1172@mindspring.com> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: Netscape 1.1N Lines: 12 In article <1995Aug23.015312.1172@mindspring.com>, fsouza@mindspring.com (Freya Souza) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Natalia Silva *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0