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Function RTUGetInterface

RTUGetInterface returns a pointer to an interface descriptor:

typedef struct { 
   BYTE bLength;              // length in bytes of this descriptor 
   BYTE bDescriptor;          // descriptor ID (4) 
   BYTE bInterfaceNumber;     // number denoting this interface 
   BYTE bAlternateSetting;    // if != 0, an alternate setting 
   BYTE bNumEndpoints;        // number of endpoints in this interface 
   BYTE bInterfaceClass;      // USB class 
   BYTE bInterfaceSubClass;   // subclass (class specific) 
   BYTE bInterfaceProtocol;   // protocol (class specific) 
   BYTE iInterface;           // index of string descr. of this interface 
} RTUInterfaceDescriptor; 

const RTUInterfaceDescriptor * 
   RTUGetInterface(const RTUConfigurationDescriptor * Config, 
                   int                                Index);

Parameters

Config

Pointer to a configuration descriptor of the configuration containing the desired interface.

Index

Zero-based index of the interface descriptor to retrieve. This parameter must be in the range 0 .. RTUAltInterfaces(Config)-1.

return value

Pointer to the desired interface descriptor or NULL if parameter Index is out of range.

To determine the number of all interface descriptors, use function RTUAltInterfaces. Member iInterface is a string descriptor index and can be used with RTUGetString to retrieve displayable information about the interface.

If a USB client wishes to use the interface, it must call RTUClaimInterface. Several interfaces of the same configuration can be claimed by a single or several clients, but no two clients can claim the same interface.

Further details about the interface descriptor are given in the USB specification.

Device Query

Function RTUAltInterfaces

Function RTUFindInterface