DeviceSubClass Property

项目
09/21/2010

The DeviceSubClass gets or sets the bDeviceSubClass field of the device qualifier descriptor, as described in section 9.6.2 of the USB 2.0 specification.

This property is read/write.

Syntax

HRESULT put_DeviceSubClass(
  [in]           BYTE bDeviceSubClass
);

HRESULT get_DeviceSubClass(
  [out, retval]  BYTE *pbDeviceSubClass
);

Property Value

The new value for the device subclass.

Error Codes

DeviceSubClass returns S_OK if the operation succeeds or E_POINTER if the pbDeviceSubClass parameter is not a valid pointer.

Remarks

The following C++ code example shows how to get and set DeviceSubClass property.

HRESULT CLoopBackDevice::SetDeviceQualifierDeviceSubClass(ISoftUSBDeviceQualifier *piQualifier)
{
HRESULT hr = S_OK;
BYTE         bDeviceSubClass = 0;
BYTE         bNewDeviceSubClass = 0xff; //Vendor specific

if (NULL == piQualifier)
{
  hr = E_INVALIDARG;
  goto Exit;
}

// Get the current device subclass value
hr = piQualifier->get_DeviceSubClass(&bDeviceSubClass);
if(FAILED(hr))
  goto Exit;
 
// Update the device subclass if required
if (bDeviceSubClass != bNewDeviceSubClass)
{
  hr = piQualifier->put_DeviceSubClass(bNewDeviceSubClass);
  if(FAILED(hr))
    goto Exit;
}
Exit:
return hr;
}

Requirements

Header

SoftUSBif.h

通过