用户空间中的ALSA PCM播放设备。

I'm having a hard time figuring out how to make a Linux PCM playback device which entirely works in user space. When the application calls snd_pcm_open/snd_pcm_readi/writei, I want does calls to end up in a user space driver and the pcm data to be handled in a thread created when the user space driver was initialized. The audio process thread will then call an actual ALSA kernel driver which will output pcm to HW. This is basically what I want to achive:I'm having a hard time figuring out how to make