Visual Basic.NET

Creating Callback Routine

Creating Callback Function

The callback function has the following format. You can specify any name for this function.

Protected Sub CallBackProc(ByVal Id As Short, ByVal wParam As Integer, ByVal lParam As Integer, ByVal Param As IntPtr)

Using Delegate

In Visual Basic, please use delegate to handle a function pointer.
The delegate declarations for each callback routine are written in the CDIO.vb file.

Registering Callback Function

Please use the following functions to register callback functions.

Flow of Registering Callback Function

.Initializing delegate
.To prevent the garbage collector from moving the delegate used for interrupt processing, get the GCHandle
.Get a stable pointer to the delegate used for interrupt processing
.Register the retrieved stable pointer by using functions such as DioSetInterruptCallBackProc function
.Release the GCHandle for the delegate used for interrupt processing, when it become unnecessary (for example, when the application terminates)

For these specific coding content, please refer to samples and Note of Using Visual Basic .NET.