[mono-android] C to C#

[Jonathan Pryor]

On Feb 20, 2012, at 12:15 PM, Goncalo Oliveira wrote:
> C header
> 
> // callback (ConnEventType is an enum)
> typedef void (*CommCallback) (ConnEventType status, unsigned long connID);
> 
> // method (callingConvention is also an enum)
> long Msg_StartUp (void *pConnEventFn, const char *pConfigPath, bool bIsProLicensed = true, bool bIsSDKLicensed = true, bool bStartConnection = true, callingConvention convention = convention_default);

The most important question: the above appears to be C++, not C (due to default parameters). Is that function declaration within an `extern "C" {` block?

> C#
> 
> // callback
> delegate void DelegateCommCallback( ConnEventType status, uint connID );

I'd suggest UIntPtr instead of `uint`, at least if this library is present on ILP32 and LP64 platforms. If it's on Windows P64, uh....

For the same reason, I'd suggest using `IntPtr` for the `long` returned by Msg_StartUp().

> // metohd
> [DllImport( "libsdk", EntryPoint = "Java_com_sdk_Msg_Msg_1StartUp", CharSet = CharSet.Auto )]
> private static extern int Msg_StartUp( DelegateCommCallback commCallback, byte[] configDir, bool isProLicensed, bool isSDKLicensed, bool startConnection, int convention );

1. Either provide the full filename or provide the "base" filename for the library, e.g. "libsdk.so" or "sdk". Mono will only try a few filename patterns when loading the native library.

2. I'm not sure why you're setting EntryPoint to a Java method name if the C method is Msg_Startup(). I would suggest omitting the EntryPoint setting.

3. What is the type of `callingConvention` in C? Is it an enum compatible with `int` or some other type?

I would suggest:

	enum CallingConvention : int {
		Default,
		// ...
	}

	[DllImport ("sdk", CharSet=CharSet.Ansi)
	IntPtr Msg_Startup (DelegateCommCallback pConnEventFn,
			string pConfigPath,
			bool bIsProLicensed=true,
			bool bStartConnection=true,
			CallingConvention convention = CallingConvention.Default);

 - Jon