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.

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

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