From ysanchez@stanford.edu Sun Jun 09 06:07:35 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!stanford!ysanchez From: ysanchez@stanford.edu (Yuki Sánchez) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jun09.060735.9838@stanford.edu> Date: Sun, 09 Jun 1996 06:07:35 GMT Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: Netscape 1.1N 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. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Yuki Sánchez Opinions expressed are solely my own and not those of Stanford University Computer Systems Lab. ------------------------------------------------------------ From akang@berkeley.edu Tue Jun 11 01:52:35 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!berkeley!akang From: akang@berkeley.edu (Aiko Kang) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jun11.015235.7898@berkeley.edu> Date: Tue, 11 Jun 1996 01:52:35 GMT References: <1996Jun09.060735.9838@stanford.edu> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Jun09.060735.9838@stanford.edu>, ysanchez@stanford.edu (Yuki Sánchez) 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. -- Aiko Kang "Hardware is temporary. The signal survives." 486DX2/66 (Linux 1.2.13) / AmigaOS 3.1