Function not found JNA + SiUSBXp

Question

I'm trying to use JNA with USBXPRESS library from SiLabs (siusbxp.dll), and while basic functions work fine, there is a problem with SI_GetDeviceProductString function.

public class usbxpress 
{

public interface SiUSBXp extends StdCallLibrary 
{
SiUSBXp INSTANCE = (SiUSBXp) Native.loadLibrary("SiUSBXp", SiUSBXp.class);

byte SI_GetNumDevices (IntByReference lpdwNumDevices);
byte SI_GetProductString( int dwDeviceNum, byte[] lpvDeviceString, int dwFlags);
byte SI_Open (int dwDevice, HANDLEByReference cyHandle);
byte SI_GetPartNumber (HANDLE cyHandle, ByteByReference lpbPartNum);        
byte SI_GetDeviceProductString (HANDLE cyHandle, PointerByReference lpProduct, ByteByReference lpbLength, int bConvertToASCII);
//byte SI_GetDeviceProductString (HANDLE cyHandle, LPVOID lpProduct, LPBYTE lpbLength, BOOL bConvertToASCII = TRUE); //original c function
}

public static void main(String[] args) 
{
//checking number of connected devices  
IntByReference lpdwNumDevices = new IntByReference();
SiUSBXp.INSTANCE.SI_GetNumDevices (lpdwNumDevices);        
System.out.println(lpdwNumDevices.getValue());

//opening the device
HANDLEByReference dev_handle_ref = new HANDLEByReference();
byte status = SiUSBXp.INSTANCE.SI_Open(0, dev_handle_ref);
System.out.printf("Status %d\n", status);

HANDLE device_handle = dev_handle_ref.getValue();

//checking part number
ByteByReference lpbPartNum = new ByteByReference();
SiUSBXp.INSTANCE.SI_GetPartNumber(device_handle, lpbPartNum);
System.out.printf("Part number is CP210%d\n", lpbPartNum.getValue());      

//checking product string - does not work
PointerByReference lpProduct = new PointerByReference();
ByteByReference lpbLength = new ByteByReference();
SiUSBXp.INSTANCE.SI_GetDeviceProductString(device_handle, lpProduct, lpbLength, 1);
}}

when I try to run it I get the following error:

> Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'SI_GetDeviceProductString': at com.sun.jna.Function.<init>(Function.java:179) 
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:391) 
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:371) 
at com.sun.jna.Library$Handler.invoke(Library.java:205) 
at $Proxy0.SI_GetDeviceProductString(Unknown Source)

It feels like it's the problem with the default argument of the C-function. I tried to use int as the argument and tried omitting it, but none of these helped. I didn't even reach the SI_Write (HANDLE cyHandle, LPVOID lpBuffer, DWORD dwBytesToWrite, LPDWORD lpdwBytesWritten, OVERLAPPED* o = NULL); function, which is promising to cause even more problems:)

Could please anyone suggest how can I deal with the default function arguments in JNA?

Update: SI_Write function works fine this way:

byte SI_Write (HANDLE cyHandle, PointerByReference lpBuffer, int dwBytesToWrite, IntByReference lpdwBytesWritten, Pointer o);
...
SiUSBXp.INSTANCE.SI_Write (device_handle, lpBuffer, message.length, lpdwBytesWritten, null);

So the problem is caused by something else, but still it exists.

Answer 1

I've managed to solve the problem by using an older version of the SiUSBXp library, which was found on the internet. Newer version downloaded from SiLabs website is acting weird - sometimes SI_GetDeviceProductString function is visible in Dependency Walker and sometimes it's not, while older one is fine.