> You may want to look at some of the audio drivers which allow you to
> mmap a buffer into userland.  From memory they handle the
> userland/kernel interaction by updating the head/tail pointers in a
> circular queue, userland updates one pointer and the kernel updates
> the other... when they pointers are equal the queue is empty.
> Unfortunately, it still needs an ioctl to kick the process along but
> the bulk data transfer is handled more efficiently.

I think our audio driver is too hard for learners to read.

(I'm also looking for a simpler code which handles ring buffer /
streams. :-)

Masao