Platform Invoke Support

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Platform invoke is a service that enables managed code to call unmanaged functions implemented in DLLs. You can use platform invoke semantically in the same way as in the full .NET Framework, but the .NET Compact Framework has a few limitations in marshaling objects and types between unmanaged and managed code.

There are three parts to a .NET Compact Framework platform invoke:

1. At design-time, the developer provides a description of the unmanaged function to call. This includes the module name (DLL file), entry point name, and calling convention.

2. At just-in-time (JIT) compile time, the common language runtime extracts this information from the metadata, locates the DLL containing the function, loads the DLL into memory and retrieves the address of the function. If the module or function is not found, the common language runtime throw a MissingMethodException.

3. At run time, the common language runtime marshals the parameters from managed format to unmanaged format before the unmanaged function is called. The common language runtime determines how to marshal each parameter based upon the managed declaration of the method.

In This Section

• DllImportAttribute Supported Fields
  Lists the subset of fields supported for the DllImportAttribute class.

• Platform Invoke Wrapper Example
  Provides example code for providing a structure for making platform invoke calls.

Related Sections

• Interop Marshaling Support
  Discusses differences in the .NET Compact Framework for marshaling data types between managed and unmanaged code.

• How to: Get the Device Platform, How to: Get the Device ID and Name, How to: Get or Set the System Time, How to: Get Device Memory, How to: Reset the Device, How to: Play Sounds, How to: Display a Gradient Fill, ,
  How-To topics demonstrate using platform invoke