snd_xfern         548 include/uapi/sound/asound.h #define SNDRV_PCM_IOCTL_WRITEN_FRAMES	_IOW('A', 0x52, struct snd_xfern)
snd_xfern         549 include/uapi/sound/asound.h #define SNDRV_PCM_IOCTL_READN_FRAMES	_IOR('A', 0x53, struct snd_xfern)