NumConfigurations Property

项目
09/21/2010

The NumConfigurations property gets or sets the bNumConfigurations 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_NumConfigurations(
  [in]           BYTE bNumConfigs
);

HRESULT get_NumConfigurations(
  [out, retval]  BYTE *pbNumConfigs
);

Property Value

The new number of configurations value for the device qualifier.

Error Codes

NumConfigurations returns S_OK if the operation succeeds or E_POINTER if the pbNumConfigs parameter is not a valid pointer.

Remarks

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

HRESULT CLoopBackDevice::SetDeviceQualifierNumConfigs(ISoftUSBDeviceQualifier *piQualifier)
{
HRESULT hr = S_OK;
BYTE         bNumConfigs = 0;
BYTE         bNewNumConfigs = 1;

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

// Get the current number of configurations
hr = piQualifier->get_NumConfigs (&bNumConfigs);
if(FAILED(hr))
  goto Exit;
 
// Update the number of configurations if required
if (bNumConfigs!= bNewNumConfigs)
{
  hr = piQualifier->put_NumConfigs (bNewNumConfigs);
  if(FAILED(hr))
    goto Exit;
}
Exit:
return hr;
}

Requirements

Header

SoftUSBif.h

通过