typedef struct { } DMA_Channel;
/*
 * Start or restart (after a stop) a DMA operation. The operation will stop
 * automatically when complete. Before this can be called, the channel must
 * have been previously set up with DMA_channel_single or DMA_channel_chain,
 * and the device must have been specified with DMA_channel_device.
 * If the operation is on a hardware device, actual transfers will begin when
 * the device requests them; if the transfer is memory to memory, transfers
 * will begin immediately.
 */
void DMA_channel_start(DMA_Channel *channel	/* DMA channel to start */);