LPOVERLAPPED_COMPLETION_ROUTINE Function Pointer

Points to a function that notifies the host when an overlapped (that is, asynchronous) I/O to a device has completed.

typedef VOID (*LPOVERLAPPED_COMPLETION_ROUTINE) (
        [in] DWORD  dwErrorCode,
        [in] DWORD  dwNumberOfBytesTransfered,
        [in] LPVOID lpOverlapped
);

Parameters

dwErrorCode

[in] A value that is an error code if the device has been closed; otherwise, this value is zero.

Closing a device causes all pending I/O to the device to be completed immediately.

dwNumberOfBytesTransfered

[in] The number of bytes transferred by the I/O operation.

lpOverlapped

[in] A pointer to a structure that contains information to be used to complete the I/O request.