CMD_START

start device processing (like ^Q)

CMD_START is a standard command for multiple audio channels. For each selected channel (io_Unit), if the allocation key (ioa_AllocKey) is correct and the channel was previously stopped (CMD_STOP), CMP_START immediately starts all writes (CMD_WRITE) to the channel. If the allocation key is incorrect, CMD_START returns an error (ADIOERR_NOALLOCATION). CMD_START starts multiple channels simultaneously to minimize distortion if the channels are playing the same waveform and their outputs are mixed. CMD_START is synchronous and only replies (mn_ReplyPort) if the quick flag (IOF_QUICK) is clear. Do not use CMD_START in interrupt code at interrupt level 5 or higher.

io_Device

Pointer to device node, must be set by (or copied from I/O block set by) OpenDevice function

io_Unit

Bit map of channels to start (bits 0 thru 3 correspond to channels 0 thru 3)

io_Command

Command number for CMD_START

io_Flags

Flags, must be cleared if not used: IOF_QUICK - (CLEAR) reply I/O request

ioa_AllocKey

Allocation key, must be set by (or copied from I/O block set by) OpenDevice function or ADCMD_ALLOCATE command

io_Unit

Bit map of channels successfully started (bits 0 thru 3 correspond to channels 0 thru 3)

io_Error

Error number: 0 - no error ADIOERR_NOALLOCATION - allocation key (ioa_AllocKey)

does not match key for channel