xrun handling in winealsa.drv

[Timofei V. Bondarenko]

Hi.

I've noticed the winealsa does not handle alsa XRUNs.
In the case of XRUN application hangs.

That's happened because return value of snd_pcm_avail_update() is not 
checked.

For example:
wavein.c
175             DWORD bytes;
180             /* read all the fragments accumulated so far */
181             frames = snd_pcm_avail_update(wwi->pcm);
182             bytes = snd_pcm_frames_to_bytes(wwi->pcm, frames);

waveout.c
476     DWORD               availInQ;
479     availInQ = snd_pcm_avail_update(wwo->pcm);
482     if (availInQ > 0) {

The snd_pcm_avail_update() returns a _signed_ type and it really does 
return negative number -EPIPE in the case of XRUN.

More over, any return value of less than period_size may indicate XRUN 
state too.
The snd_pcm_state() may help then.

Th dsoutput.c and dscapture.c do exactly the same wrong thigs.

BTW, using DWORD type causes problems.
Following fragment is from wavein.c too:

177             DWORD read;
181             frames = snd_pcm_avail_update(wwi->pcm);
182             bytes = snd_pcm_frames_to_bytes(wwi->pcm, frames);
193                     read = wwi->read(wwi->pcm, lpWaveHdr->lpData + 
194                     bytesRead = snd_pcm_frames_to_bytes(wwi->pcm, 
197                     if (bytesRead != (DWORD) -1)

This is obviously will not work as expected.

I hope someone will fix these issues :)

Regards,
	Tim.