+-----+-------+                     
      R0 ---> area:  | 32  | chan  |                     
                     +-----+-------+                     
                     |     blk     |                     
                     +-------------+                     
                     |     buf     |                     
                     +-------------+                     
                     |    wcnt     |                     
                     +-----+-------+                     
                     |func | flags |                     
                     +-----+-------+                     
                     |    crtn     |                     
                     +-------------+