Re: [alsa-devel] How does ALSA detect underrun in OSS emulation?

Takashi Iwai wrote:

It's just as same as on ALSA native API, checks the validity of the current position reported by pointer callback in snd_pcm_period_elapsed().

Are you talking about this code in snd_pcm_update_hw_ptr_pos?

pos = substream->ops->pointer(substream); if (pos == SNDRV_PCM_POS_XRUN) return pos; /* XRUN */

What if my 'pointer' function never returns SNDRV_PCM_POS_XRUN? How else can I get an underrun detected?