Creating a DriverProc Function

You create a DriverProcJIGHER function in much the same way as you create a window procedure. The function consists of a switch statement, and each case processes a given driver message, returning a value indicating success or failure. The DriverProc function has the following form:

LONG DriverProc(DWORD dwDriverId, HDRVR hdrvr, UINT msg,
    LONG lParam1, LONG lParam2)
{ 
    DWORD dwRes = 0L;

    switch (msg) { 
    case DRV_LOAD:
    // Sent when the driver is loaded. This is always  
    // the first message received by a driver.
        dwRes = 1L;  // returns 0L to fail
        break;

    case DRV_FREE:
    // Sent when the driver is about to be discarded.
    // This is the last message a driver receives
    // before it is freed.
        dwRes = 1L;  // return value ignored
        break;

    case DRV_OPEN:
    // Sent when the driver is opened.
        dwRes = 1L;  // returns 0L to fail
        break;       // value subsequently used
                     // for dwDriverId.

    case DRV_CLOSE:
    // Sent when the driver is closed. Drivers are
    // unloaded when the open count reaches zero.
        dwRes = 1L;  // returns 0L to fail
        break;

    case DRV_ENABLE:
    // Sent when the driver is loaded or reloaded and
    // when Windows is enabled. Install interrupt
    // handlers and initialize hardware. Expect the
    // driver to be in memory only between the enable
    // and disable messages.
        dwRes = 1L;  // return value ignored
        break;

    case DRV_DISABLE:
    // Sent before the driver is freed or when Windows
    // is disabled. Remove interrupt handlers and place
    // hardware in an inactive state.
        dwRes = 1L;  // return value ignored
        break;

    case DRV_INSTALL:
    // Sent when the driver is installed.
        dwRes = DRVCNF_OK;  // Can also return
        break;              // DRVCNF_CANCEL
                            // and DRV_RESTART

    case DRV_REMOVE:
    // Sent when the driver is removed.
        dwRes = 1L;  // return value ignored
        break;

    case DRV_QUERYCONFIGURE:
    // Sent to determine if the driver can be
    // configured.
        dwRes = 0L;  // Zero indicates configuration
        break;       // NOT supported

    case DRV_CONFIGURE:
    // Sent to display the configuration
    // dialog box for the driver.
        dwRes = DRVCNF_OK;  // Can also return
        break;              // DRVCNF_CANCEL
                            // and DRVCNF_RESTART

    default:
    // Process any other messages.
        return DefDriverProc (dwDriverId, hdrvr,
            msg, lParam1, lParam2);

    }
    return dwRes;
}