Docs » Autodocs » audio.device » ADCMD_PERVOL
ADCMD_PERVOL -- change the period and volume for writes in progress to
audio channels
ADCMD_PERVOL is a command for multiple audio channels. For each
selected channel (io_Unit), if the allocation key (ioa_AllocKey) is
correct and there is a write (CMD_WRITE) in progress, ADCMD_PERVOL
loads a new volume and period immediately or at the end of the current
cycle depending on the sync flag (ADIOF_SYNCCYCLE). If the allocation
key in incorrect, ADCMD_PERVOL returns an error
(ADIOERR_NOALLOCATION). ADCMD_PERVOL is synchronous and only replies
(mn_ReplyPort) if the quick flag (IOF_QUICK) is clear. Do not use
ADCMD_PERVOL in interrupt code at interrupt level 5 or higher.
mn_ReplyPort- pointer to message port that receives I/O request
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 load period and volume (bits 0
thru 3 correspond to channels 0 thru 3)
io_Command - command number for ADCMD_PERVOL
io_Flags - flags, must be cleared if not used:
IOF_QUICK - (CLEAR) reply I/O request
ADIOF_SYNCCYCLE- (CLEAR) load period and volume
immediately
(SET) load period and volume at the end
of the current cycle
ioa_AllocKey- allocation key, must be set by (or copied from I/O block
set by) OpenDevice function or ADCMD_ALLOCATE command
ioa_Period - new sample period in 279.365 ns increments (124 thru
65536, anti-aliasing filter works below 300 to 500
depending on waveform)
ioa_Volume - new volume (0 thru 64, linear)
io_Unit - bit map of channels that successfully loaded period and
volume (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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