dll loading trouble

[ldynasa]

Here I've got a dll written in C downloaded from the internet. The library is successfully loaded in Qt, functions resolved. But calling these methods causes the app to crash with "Segmentation fault". Besides, I've built a C# project in VS08 and loaded the library. Everything works again.

Here's the code:
1.dll library:

void fdlib_detectfaces(unsigned char *imagedata, int imagewidth, int imageheight, int threshold);

2.Qt app:

ushort graydata[10*10];
QLibrary mylib("\\fdlib.dll");
bool okLoad = mylib.load();
bool loaded = mylib.isLoaded();
typedef void (*FdetectFace)(ushort*,int,int,int);
FdetectFace detectFace = (FdetectFace)mylib.resolve("fdlib_detectfaces");
 
//app crashes here
detectFace(&graydata[0],10,10,0);

ushort graydata[10*10];
QLibrary mylib("\\fdlib.dll");
bool okLoad = mylib.load();
bool loaded = mylib.isLoaded();
typedef void (*FdetectFace)(ushort*,int,int,int);
FdetectFace detectFace = (FdetectFace)mylib.resolve("fdlib_detectfaces");

//app crashes here
detectFace(&graydata[0],10,10,0);

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3.C# implementation:

[DllImport("fdlib.dll")]

unsafe public static extern void fdlib_detectfaces(ushort*data,int w,int h,int threshold);
 
public static void TestFace()
        {
            unsafe
            {
                UInt16[] image = new ushort[10 * 10];
                fixed (ushort* ptr = &image[0])
                {
                    fdlib_detectfaces(ptr, 10, 10, 0);
                }
            }
        }

unsafe public static extern void fdlib_detectfaces(ushort*data,int w,int h,int threshold);

public static void TestFace()
        {
            unsafe
            {
                UInt16[] image = new ushort[10 * 10];
                fixed (ushort* ptr = &image[0])
                {
                    fdlib_detectfaces(ptr, 10, 10, 0);
                }
            }
        }

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