From bnilsson@uu.net Sun Aug 06 11:11:33 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!uu!bnilsson From: bnilsson@uu.net (Bastien Nilsson) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug06.111133.6481@uu.net> Date: Sun, 06 Aug 1995 11:11:33 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: WinVN 0.99.5 Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Bastien Nilsson "We don't sign stars. We build them." Pentium 90 (OS/2 Warp) / System 7.5.1 From kito@uni-hamburg.de Sun Aug 06 20:53:33 1995 Path: ashpoly!cascade!mxgate!coyoacan!uni-hamburg!kito From: kito@uni-hamburg.de (Kenji Ito) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug06.205333.6741@uni-hamburg.de> Date: Sun, 06 Aug 1995 20:53:33 GMT References: <1995Aug06.111133.6481@uu.net> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Aug06.111133.6481@uu.net>, bnilsson@uu.net (Bastien Nilsson) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Kenji Ito | kito@uni-hamburg.de PGP Key fingerprint: 3A26 CD5A 3BFF 3BFB "Keep the channels open." From llarsson@uu.net Tue Aug 08 10:13:33 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!uu!llarsson From: llarsson@uu.net (Lucia Larsson) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug08.101333.6332@uu.net> Date: Tue, 08 Aug 1995 10:13:33 GMT References: <1995Aug06.111133.6481@uu.net> <1995Aug06.205333.6741@uni-hamburg.de> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Aug06.205333.6741@uni-hamburg.de>, kito@uni-hamburg.de (Kenji Ito) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Lucia Larsson | llarsson@uu.net PGP Key fingerprint: CF6A B7AF E3CE C418 "Keep the channels open." From ltanaka@rwth-aachen.de Tue Aug 08 18:42:33 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!rwth-aachen!ltanaka From: ltanaka@rwth-aachen.de (Lucia Tanaka) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug08.184233.7839@rwth-aachen.de> Date: Tue, 08 Aug 1995 18:42:33 GMT References: <1995Aug06.111133.6481@uu.net> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Aug06.111133.6481@uu.net>, bnilsson@uu.net (Bastien Nilsson) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Lucia Tanaka SupraFAXModem 28.8 @ ISDN 64k bps "A soul is not exclusive to biology."