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Driver Description Structure

The structure DriverDescription is used to match drivers with devices, set up and maintain a driver's run-time environment, and declare a driver's supported services.



 
struct DriverDescription {

    OSType              driverDescSignature;

    DriverDescVersion   driverDescVersion;

    DriverType          driverType;

    DriverOSRuntime     driverOSRuntimeInfo;

    DriverOSService     driverServices;

};



typedef struct DriverDescription DriverDescription;

typedef struct DriverDescription *DriverDescriptionPtr;



enum {

kTheDescriptionSignature = 'mtej'       /* first long word of */

                                            /* DriverDescription */

};



typedef UInt32 DriverDescVersion;

    enum {

    kInitialDriverDescriptor = 0        /* first version of */

                                        /* DriverDescription */

};

Field descriptions

driverDescSignature: Signature of this DriverDescription structure; currently 'mtej' is used for all. Replace with the constant kTheDescriptionSignature
driverDescVersion: Version of this driver description structure, used to distinguish different versions of DriverDescription that have the same driverDescSignature value.
driverType: Structure that contains driver name and version.
driverOSRuntimeInfo: Structure that contains driver run-time information, which determines how a driver is handled when Mac OS finds it. This structure also provides the driver's name to Mac OS and specifies the driver's ability to support concurrent requests.
driverServices: Structure used to declare the driver's supported programming interfaces.

The driverType, driverOSRuntimeInfo, and driverServices structures are described in the next sections. A typical driver description is shown in Listing 8-1.

Listing 8-1 Typical driver description



 
DriverDescription TheDriverDescription =

{

    // signature info

        kTheDescriptionSignature,           // signature always first

        kInitialDriverDescriptor,           // version second



    // type info

    {

        "\pAAPL,Viper",                     // device's name (must match

                                            // name in Name Registry)

        0x1,0x0,0x40,0x2,                   // Rev 1.0.0a2

    },



    // OS run-time requirements

    {

        kDriverIsUnderExpertControl         // run-time options

        | kDriverIsOpenedUponLoad,                  

        "\p.Display_Video_Apple_Viper",

    },



    // OS run-time info

    {

        1,                              // number of service categories

        {

            kServiceCategoryNdrvDriver,     // supports 'ndrv' category

            kNdrvTypeIsVideo,               // video type



    // Version of service

            1, 0, 0, 0                      // major, minor, stage, rev

        }

    }

};