Yea; it's double-buffering in a ring buffer? Or maybe I don't really understand ring buffers or the terminology; thought I did from the article, since it said they were called circular buffers, and you set up the DMA in "circular" mode for this, and it's using a buffer!

Half-transfer means when 1/2 of the DMA transfer size is done, an interrupt fires. So, you can use this and full-transfer interrupts to manage the sequencing.