Access Violation with signal emit

[antz24]

Hello All,

I am trying to create a GUI which interfaces with a 3rd party DLL and API for a frame grabber board. Within the dll there is a callback function which interfaces with an interrupt which allows users to synchronize their applications. The callback creates a thread and allows users to store raw data to allocated memory and manipulate the data as they please . The issue i am having is signaling my custom slot which essentially refreshes the image with whatever is stored in the allocated memory buffer. Whenever i emit a signal i receive a memory allocation error. Below is call stack:

Unhandled exception at 0x661c7c1a (Qt5Cored.dll) in MatrixPCIe_ARINC818_GUI_QT.exe: 0xC0000005: Access violation reading location 0x000000000000001a.

> Qt5Cored.dll!QScopedPointer<QObjectData,QScopedPoi nterDeleter<QObjectData> >::data() Line 132 + 0x5 bytes C++
Qt5Cored.dll!qGetPtrHelper<QScopedPointer<QObjectD ata,QScopedPointerDeleter<QObjectData> > >(const QScopedPointer<QObjectData,QScopedPointerDeleter<Q ObjectData> > & p) Line 886 + 0x13 bytes C++
Qt5Cored.dll!QObject::d_func() Line 118 + 0x1a bytes C++
Qt5Cored.dll!QMetaObject::activate(QObject * sender, int signalOffset, int local_signal_index, void * * argv) Line 3364 + 0xd bytes C++
Qt5Cored.dll!QMetaObject::activate(QObject * sender, const QMetaObject * m, int local_signal_index, void * * argv) Line 3355 C++
MatrixPCIe_ARINC818_GUI_QT.exe!MatrixPCIe_ARINC818 _GUI_QT::rawDataChanged(unsigned int * _t1) Line 153 C++
MatrixPCIe_ARINC818_GUI_QT.exe!UserCallBack(unsign ed int u32Param) Line 251 C++

Thanks for your help.

[wysota]

Looks like you have a null pointer somewhere. My guess would be that this is thread synchronisation issue in your code.