VPEND_LOAD

Initializes variables so the tablet can later be enabled.

• If successful, returns a handle that the driver uses when it needs to enable or disable interrupts to itself. (This handle is also in the EAX register.) The handle can also be used when the driver sends a subsequent DRV_FREE message. Otherwise, returns DRV_FAILURE.

lParam1

Pointer to a VPEND_INIT structure.

lParam2

Should be set to zero.

The virtual driver receives the VPEND_LOAD message every time a process registers to receive interrupt callbacks from the virtual pen driver. When sent from the ring 3 driver, the DS:SI registers (or SS:SI, if DS=SS) should contain a pointer to a VpenD_Init structure. The virtual driver stores all the information in the _VpenD_Register structure for future reference.

This routine can be called from either a driver in the system virtual machine (VM) or from a driver in some MS-DOS VM. Every time the user switches VMs, the system notifies the virtual pen driver. This enables the virtual pen driver to route pen packets to the current VM, if a device in that VM has registered to receive pen information. This functionality is not provided in the sample virtual pen driver code.

At this time, only one device in each VM can register to receive pen packet information. If a driver has already registered for the VM that this driver is currently requesting to serve, this routine will return DRV_FAILURE.