From tmoreau@clari.net Thu Sep 21 12:22:03 1995 Path: ashpoly!cascade!bigsur!clari!tmoreau From: tmoreau@clari.net (Takeshi Moreau) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Sep21.122203.5624@clari.net> Date: Thu, 21 Sep 1995 12:22:03 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Takeshi Moreau Tape trading list upon request. SASE required for international mail. From hokonkwo@netcom.com Thu Sep 21 18:16:03 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!netcom!hokonkwo From: hokonkwo@netcom.com (Hugo Okonkwo) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Sep21.181603.3436@netcom.com> Date: Thu, 21 Sep 1995 18:16:03 GMT References: <1995Sep21.122203.5624@clari.net> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Sep21.122203.5624@clari.net>, tmoreau@clari.net (Takeshi Moreau) 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. -- Hugo Okonkwo *PLONK* filter active for trolls. Atari Falcon 030 - NetBSD 1.0 From snilsson@utexas.edu Fri Sep 22 14:08:03 1995 Path: ashpoly!cascade!mxgate!coyoacan!utexas!snilsson From: snilsson@utexas.edu (Sven Nilsson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Sep22.140803.9426@utexas.edu> Date: Fri, 22 Sep 1995 14:08:03 GMT References: <1995Sep21.122203.5624@clari.net> <1995Sep21.181603.3436@netcom.com> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Sep21.181603.3436@netcom.com>, hokonkwo@netcom.com (Hugo Okonkwo) 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! If you are posting from AOL, please read RFC 1036 before posting again. -- Sven Nilsson Tape trading list upon request. SASE required for international mail. From phernandez@pipeline.com Sat Sep 23 03:07:03 1995 Path: ashpoly!cascade!brgate!saturno!pipeline!phernandez From: phernandez@pipeline.com (Pavel Hernández) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Sep23.030703.2716@pipeline.com> Date: Sat, 23 Sep 1995 03:07:03 GMT References: <1995Sep21.122203.5624@clari.net> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Sep21.122203.5624@clari.net>, tmoreau@clari.net (Takeshi Moreau) 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. -- Pavel Hernández -- The Pipeline Internet Network "Row 14. No joke."