From dnilsson@kth.se Sun Dec 04 07:12:41 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!kth!dnilsson From: dnilsson@kth.se (Dong-hyun Nilsson) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Dec04.071241.8625@kth.se> Date: Sun, 04 Dec 1994 07:12:41 GMT Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: NewsWatcher 2.0b24 Lines: 10 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. -- Dong-hyun Nilsson -- Royal Institute of Technology, Stockholm "The hatch is open. Is anyone listening?" From bnovak@titech.ac.jp Sun Dec 04 12:50:41 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!titech!bnovak From: bnovak@titech.ac.jp (Bastien Novak) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Dec04.125041.6607@titech.ac.jp> Date: Sun, 04 Dec 1994 12:50:41 GMT References: <1994Dec04.071241.8625@kth.se> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1994Dec04.071241.8625@kth.se>, dnilsson@kth.se (Dong-hyun Nilsson) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. If you are posting from AOL, please read RFC 1036 before posting again. -- Bastien Novak Hayes Optima 288 @ 33,600 bps "Row 14. No joke." From lsato@earthlink.net Tue Dec 06 04:49:41 1994 Path: ashpoly!cascade!transat!ukc!fennimore!earthlink!lsato From: lsato@earthlink.net (Lisa Sato) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Dec06.044941.1068@earthlink.net> Date: Tue, 06 Dec 1994 04:49:41 GMT References: <1994Dec04.071241.8625@kth.se> <1994Dec04.125041.6607@titech.ac.jp> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Dec04.125041.6607@titech.ac.jp>, bnovak@titech.ac.jp (Bastien Novak) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Lisa Sato *PLONK* filter active for trolls. Acorn RiscPC 600 - NetBSD 1.0