Docs » Autodocs » audio.device » CMD_START
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 an
d
only replies (mn_ReplyPort) if the quick flag (IOF_QUICK) is clear. D
o
not use CMD_START in interrupt code at interrupt level 5 or higher.
mn_ReplyPort- pointer to message port that receives I/O request after
if the quick flag (IOF_QUICK) is clear
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
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