From beriksson@mindspring.com Tue Jun 06 23:29:38 1995 Path: ashpoly!cascade!mxgate!coyoacan!mindspring!beriksson From: beriksson@mindspring.com (Brian Eriksson) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jun06.232938.5147@mindspring.com> Date: Tue, 06 Jun 1995 23:29:38 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com 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. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Brian Eriksson Practical Peripherals 14.4 @ ISDN 64k bps "Extraordinary claims require extraordinary spectra." From lsokolov@uu.net Wed Jun 07 03:12:38 1995 Path: ashpoly!cascade!mxgate!coyoacan!uu!lsokolov From: lsokolov@uu.net (Lisa Sokolov) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jun07.031238.3035@uu.net> Date: Wed, 07 Jun 1995 03:12:38 GMT References: <1995Jun06.232938.5147@mindspring.com> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Jun06.232938.5147@mindspring.com>, beriksson@mindspring.com (Brian Eriksson) 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. -- Lisa Sokolov *PLONK* filter active for trolls. Macintosh IIfx - NetBSD 1.0 From ktakahashi@rwth-aachen.de Wed Jun 07 12:02:38 1995 Path: ashpoly!cascade!mxgate!coyoacan!rwth-aachen!ktakahashi From: ktakahashi@rwth-aachen.de (Karen Takahashi) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jun07.120238.7105@rwth-aachen.de> Date: Wed, 07 Jun 1995 12:02:38 GMT References: <1995Jun06.232938.5147@mindspring.com> <1995Jun07.031238.3035@uu.net> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Jun07.031238.3035@uu.net>, lsokolov@uu.net (Lisa Sokolov) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Karen Takahashi Opinions expressed are solely my own and not those of RWTH Aachen Informatik. ------------------------------------------------------------