From dfischer@panix.com Sun Aug 11 19:01:56 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!panix!dfischer From: dfischer@panix.com (Diego Fischer) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Aug11.190156.5808@panix.com> Date: Sun, 11 Aug 1996 19:01:56 GMT Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: WinVN 0.99.5 Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Diego Fischer "In theory there is no difference between theory and practice." Mac IIci / 68882 FPU / System 7.5.1 From joliveira@delphi.com Sun Aug 11 20:00:56 1996 Path: ashpoly!cascade!brgate!saturno!delphi!joliveira From: joliveira@delphi.com (Julien Oliveira) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Aug11.200056.2077@delphi.com> Date: Sun, 11 Aug 1996 20:00:56 GMT References: <1996Aug11.190156.5808@panix.com> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: TIN [version 1.2 PL2] Lines: 12 In article <1996Aug11.190156.5808@panix.com>, dfischer@panix.com (Diego Fischer) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Julien Oliveira Opinions expressed are solely my own and not those of Delphi Internet Services. ------------------------------------------------------------