public static extern bool SetupDiGetDeviceInterfaceDetail( IntPtr deviceInfoSet, ref SpDeviceInterfaceData deviceInterfaceData, IntPtr deviceInterfaceDetailData, Int32 deviceInterfaceDetailDataSize, ref Int32 requiredSize, IntPtr deviceInfoData);
public static bool FindHidDevices(ref string[] listOfDevicePathNames, ref int numberOfDevicesFound)
{
Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> Method called");
// Initialise the internal variables required for performing the search
var bufferSize = 0;
var detailDataBuffer = IntPtr.Zero;
bool deviceFound;
var deviceInfoSet = new IntPtr();
var lastDevice = false;
int listIndex;
var deviceInterfaceData = new SpDeviceInterfaceData();
// Get the required GUID
var systemHidGuid = new Guid();
Hid.HidD_GetHidGuid(ref systemHidGuid);
Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> Fetched GUID for HID devices ({0})", systemHidGuid.ToString());
try
{
// Here we populate a list of plugged-in devices matching our class GUID (DIGCF_PRESENT specifies that the list
// should only contain devices which are plugged in)
Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> Using SetupDiGetClassDevs to get all devices with the correct GUID");
deviceInfoSet = SetupApi.SetupDiGetClassDevs(ref systemHidGuid, IntPtr.Zero, IntPtr.Zero, Constants.DigcfPresent | Constants.DigcfDeviceinterface);
// Reset the deviceFound flag and the memberIndex counter
deviceFound = false;
listIndex = 0;
deviceInterfaceData.cbSize = Marshal.SizeOf(deviceInterfaceData);
// Look through the retrieved list of class GUIDs looking for a match on our interface GUID
do
{
//Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> Enumerating devices");
var success = SetupApi.SetupDiEnumDeviceInterfaces(deviceInfoSet, IntPtr.Zero, ref systemHidGuid, listIndex, ref deviceInterfaceData);
if (!success)
{
//Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> No more devices left - giving up");
lastDevice = true;
}
else
{
// The target device has been found, now we need to retrieve the device path so we can open
// the read and write handles required for USB communication
// First call is just to get the required buffer size for the real request
SetupApi.SetupDiGetDeviceInterfaceDetail
(deviceInfoSet,
ref deviceInterfaceData,
IntPtr.Zero,
0,
ref bufferSize,
IntPtr.Zero);
// Allocate some memory for the buffer
detailDataBuffer = Marshal.AllocHGlobal(bufferSize);
Marshal.WriteInt32(detailDataBuffer, (IntPtr.Size == 4) ? (4 + Marshal.SystemDefaultCharSize) : 8);
// Second call gets the detailed data buffer
//Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> Getting details of the device");
SetupApi.SetupDiGetDeviceInterfaceDetail
(deviceInfoSet,
ref deviceInterfaceData,
detailDataBuffer,
bufferSize,
ref bufferSize,
IntPtr.Zero);
// Skip over cbsize (4 bytes) to get the address of the devicePathName.
var pDevicePathName = new IntPtr(detailDataBuffer.ToInt32() + 4);
// Get the String containing the devicePathName.
listOfDevicePathNames[listIndex] = Marshal.PtrToStringAuto(pDevicePathName);
//Debug.WriteLine(string.Format("usbGenericHidCommunication:findHidDevices() -> Found matching device (memberIndex {0})", memberIndex));
deviceFound = true;
}
listIndex = listIndex + 1;
}
while (lastDevice != true);
}
catch (Exception)
{
// Something went badly wrong... output some debug and return false to indicated device discovery failure
Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> EXCEPTION: Something went south whilst trying to get devices with matching GUIDs - giving up!");
return false;
}
finally
{
// Clean up the unmanaged memory allocations
if (detailDataBuffer != IntPtr.Zero)
{
// Free the memory allocated previously by AllocHGlobal.
Marshal.FreeHGlobal(detailDataBuffer);
}
if (deviceInfoSet != IntPtr.Zero)
{
SetupApi.SetupDiDestroyDeviceInfoList(deviceInfoSet);
}
}
if (deviceFound)
{
Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> Found {0} devices with matching GUID", (listIndex - 1).ToString(CultureInfo.InvariantCulture));
numberOfDevicesFound = listIndex - 2;
}
else Debug.WriteLine("usbGenericHidCommunication:findHidDevices() -> No matching devices found");
return deviceFound;
}
public static extern bool SetupDiEnumDeviceInterfaces(IntPtr deviceInfoSet, IntPtr deviceInfoData, ref Guid hidGuid, Int32 memberIndex, ref SpDeviceInterfaceData deviceInterfaceData);
