From: brodskye at cae.wisc.edu
Newsgroups: alt.sb.programmer
Subject: Re: Need help on (auto)detecting SB
References: <33b48f6a.2991144@news.pi.net>
Reply-To: ebrodsky@pobox.com
Organization: Capital Sound Programming

In article <33b48f6a.2991144@news.pi.net>,  <Willem Romijn> wrote:
>Could someone plz point me to some sources on how to detect the
>presence of a soundblaster card? I also would like to autodetect
>address, irq and dma if that's possible.

for source, look around the ftp site x2ftp.oulu.fi.  I believe
there are a couple of SB detection programs available there.  

Autodetecting the address is the easiest.  You iterate through
each address though, attempting to reset the card.  If it is
successful, then you've found it; if not, try another.

Detecting the IRQ is a bit harder.  The usual way to do this
is to install a handler on each IRQ supported by a sound card,
then trigger an interrupt, detecting which handler is called.
There are two ways to trigger an interrupt.  The easiest is
to write DSP command 0xF2.  However, this is undocumented and
may not work on all sound cards.  A more reliable method would
be to run a short DMA transfer, but this requires using a DMA
channel.

Detecting the DMA channel is the most difficult.  The only
way I've found to do this is to program a transfer and see
what channel it goes on.  I've never tried this myself, so
I have several theories on how to detect the channel.  One
is to program the transfer with the DSP, then examine the 
DRQ register to see whether which channel has a request.  If
this doesn't work, you can program each channel in turn 
until it works.  

If you're using a SB16, you can read the IRQ and DMA channel
from a register in the mixer, making detection only a matter
of finding the base address.

I've never written any detection code myself, although I've
looked at the source code for a few and disassembled one,
though none supported DMA.  I have seen a program that 
detects DMA though, so I know it's possible.

If I find some time, maybe I'll write some code to detect
sound card.  I've been suggesting these techniques for years
without ever having tried them myself.

    Ethan Brodsky