From cfournier@demon.co.uk Mon Jun 20 13:22:14 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!demon!cfournier
From: cfournier@demon.co.uk (Camila Fournier)
Newsgroups: comp.sys.m68k
Subject: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun20.132214.5195@demon.co.uk>
Date: Mon, 20 Jun 1994 13:22:14 GMT
Organization: Demon Internet Services UK
NNTP-Posting-Host: demon.co.uk
X-Newsreader: WinVN 0.99.5
Lines: 10

Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.

I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.
By setting up Paula's audio DMA to double-buffer incoming 8-bit samples, the 68020 has plenty of cycles left for the Costas loop.

Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week.

-- 
Camila Fournier -- Demon Internet Services UK
"Extraordinary claims require extraordinary spectra."

From neriksson@tum.de Tue Jun 21 09:19:14 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!tum!neriksson
From: neriksson@tum.de (Natalia Eriksson)
Newsgroups: comp.sys.m68k
Subject: Re: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun21.091914.4073@tum.de>
Date: Tue, 21 Jun 1994 09:19:14 GMT
References: <1994Jun20.132214.5195@demon.co.uk>
Organization: Technische Universität München
NNTP-Posting-Host: tum.de
X-Newsreader: Netscape 1.1N
Lines: 10

In article <1994Jun20.132214.5195@demon.co.uk>, cfournier@demon.co.uk (Camila Fournier) writes:
> Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.
> I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.

Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window.

-- 
Natalia Eriksson
Opinions expressed are solely my own and not those of Technische Universität München.
------------------------------------------------------------

From kpetrov@mit.edu Thu Jun 23 05:21:14 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!mit!kpetrov
From: kpetrov@mit.edu (Karen Petrov)
Newsgroups: comp.sys.m68k
Subject: Re: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun23.052114.9732@mit.edu>
Date: Thu, 23 Jun 1994 05:21:14 GMT
References: <1994Jun20.132214.5195@demon.co.uk> <1994Jun21.091914.4073@tum.de>
Organization: Massachusetts Institute of Technology
NNTP-Posting-Host: mit.edu
X-Newsreader: Netscape 1.1N
Lines: 8

In article <1994Jun21.091914.4073@tum.de>, neriksson@tum.de (Natalia Eriksson) writes:
> Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window.

Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom.

-- 
Karen Petrov
Tape trading list upon request. SASE required for international mail.