ADCMD_FREE

free audio channels for allocation

ADCMD_FREE is a command for multiple audio channels. For each selected channel (io_Unit), if the allocation key (ioa_AllocKey) is correct, ADCMD_FREE does the following:

• Restores the channel to a known state (CMD_RESET),
  
  
• Changes the channels allocation key, and
  
  
• Makes the channel available for re-allocation.
  
  
• If the channel is locked (ADCMD_LOCK) ADCMD_FREE unlocks it and clears the bit for the channel (io_Unit) in the lock I/O request. If the lock I/O request has no channel bits set ADCMD_FREE replies the lock I/O request, and
  
  
• Checks if there are allocation requests (ADCMD_ALLOCATE) waiting for the channel.
  
  

Otherwise, ADCMD_FREE returns an error (ADIOERR_NOALLOCATION). ADCMD_FREE is synchronous and only replies (mn_ReplyPort) if the quick flag (IOF_QUICK) is clear. Do not use ADCMD_FREE in interrupt code.

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 free (bits 0 thru 3 correspond to channels 0 thru 3)

io_Command

Command number for ADCMD_FREE

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 freed (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