ChangerAdditionalExtensionSize function (mcd.h)
ChangerAdditionalExtensionSize indicates the number of bytes the changer miniclass driver requires to store device-specific information in the device extension.
Syntax
ULONG ChangerAdditionalExtensionSize();
Return value
ChangerAdditionalExtensionSize returns the size, in bytes, of the additional device extension space required by the changer miniclass driver.
Remarks
The changer class driver calls ChangerAdditionalExtensionSize to determine the number of bytes the miniclass driver requires in the device extension for a particular changer before creating the device object to represent that changer.
The device-specific information stored by a changer miniclass driver is determined by the driver. It typically includes zero-based offsets that other miniclass driver routines can use to translate between device-specific element addresses and the zero-based element addresses used by the system. It can also include SCSI inquiry data or the non-SCSI equivalent.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Desktop |
| Header | mcd.h (include Mcd.h, Ntddchgr.h) |
| IRQL | PASSIVE_LEVEL |