Sound Programming and Signals

Sound Programming and Signals

[Chuck Winters]

I am trying to write a program which get a SIGIO signal from a
sound device, and then selects on the fd to decide if the device
can accept write, read, exception data.  The problem is that
it doesn't seem like the device every raises a SIGIO signal.  If
I do a kill -SIGIO <test_pid>, my handler runs.  Anyone have any ideas?

Chuck

Re: Sound Programming and Signals

[Glynn Clements]

Chuck Winters wrote:

> I am trying to write a program which get a SIGIO signal from a
> sound device, and then selects on the fd to decide if the device
> can accept write, read, exception data.  The problem is that
> it doesn't seem like the device every raises a SIGIO signal.  If
> I do a kill -SIGIO <test_pid>, my handler runs.  Anyone have any ideas?

1. Did you set the O_ASYNC flag on the descriptor, either in the call
to open(), or with a subsequent call to fcntl(fd, F_SETFL, O_ASYNC)?

2. Did you set the target process ID with fcntl(fd, F_SETOWN, pid)?

If you have done both of these, but you still don't receive SIGIO,
then I would suspect that it's a limitation of the sound card driver.

-- 
Glynn Clements <glynn.clements@virgin.net>

Re: Sound Programming and Signals

[chuckw]

On Thu, Jun 13, 2002 at 10:48:00PM +0100, Glynn Clements wrote:
> 
> Chuck Winters wrote:
> 
> > I am trying to write a program which get a SIGIO signal from a
> > sound device, and then selects on the fd to decide if the device
> > can accept write, read, exception data.  The problem is that
> > it doesn't seem like the device every raises a SIGIO signal.  If
> > I do a kill -SIGIO <test_pid>, my handler runs.  Anyone have any ideas?
> 
> 1. Did you set the O_ASYNC flag on the descriptor, either in the call
> to open(), or with a subsequent call to fcntl(fd, F_SETFL, O_ASYNC)?
I used fcntl(fd, F_SETFL, f_flags|F_ASYNC)
after I used the F_SETOWN fcntl.  
> 
> 2. Did you set the target process ID with fcntl(fd, F_SETOWN, pid)?
> 
> If you have done both of these, but you still don't receive SIGIO,
> then I would suspect that it's a limitation of the sound card driver.
That really sucks then.  I thought all the drivers would support that.

Thanks
Chuck