Question

I have the following problem:

public class ListenThread : SocketInvoke
{
            [DllImport("Ws2_32", CharSet = CharSet.Auto)]
            public unsafe static extern UInt32 WSAWaitForMultipleEvents(UInt32 cEvents, IntPtr hEventObject,
            UInt32 fWaitAll, UInt32 dwTimeout, Boolean fAlertable);

            public void ListenConnections(NetSharedData data)
            {
                while (true)
                {
                    unsafe
                    {
                        if (WSAWaitForMultipleEvents((UInt32)1, data.signal, (UInt32)0, (UInt32)100, false) != WSA_WAIT_TIMEOUT)
                        {
                        }
                   }
             }
}

data.signal is a UInt32 how i can cast it to IntPtr?, i try:

IntPtr signal = (IntPtr)data.signal;

but it doesn’t work because i need a pointer to data.signal (UInt32) type and not the int value as an pointer, that will make a memory exception.

An C++ example of what i need:

int signal = 0;
int* psignal = &signal;

Answer 1

new IntPtr(data.signal);

You are going to have problems on a 64-bit platform because data.signal is only hanging on to the lower 32-bits of an address. If NetSharedData is yours you should consider changing the type of signal to IntPtr.

If you are trying to get an address to data.signal:

new IntPtr(&data.signal);

I’m not sure this would properly pin the object (to prevent the memory manager from relocating it), I would do the following:

1) Change the PInvoke signature:

public unsafe static extern UInt32 WSAWaitForMultipleEvents(UInt32 cEvents, 
       void* hEventObject, UInt32 fWaitAll, UInt32 dwTimeout, Boolean fAlertable);

2) use fixed to pin the object

fixed (void* s = &data.signal)
{
    if (WSAWaitForMultipleEvents((UInt32)1, s, (UInt32)0, (UInt32)100, false) != WSA_WAIT_TIMEOUT)
    {
    }
}