Hello everybody, I need some help with Alien on Mac OS X 10.6.3 in Pharo 1.0. I am calling a function from a vtable struct in the Java Native Interface of the Java VM which comes with Mac OS X and which is defined as jint ( __stdcall * GetVersion)(JNIEnv * env); The result type jint is just an alias for int. The Smalltalk method is ---- primGetVersion | functionPointer result vtablePointer | vtablePointer := Alien atAddress: self externalData asUnsignedLong dataSize: Alien sizeofPointer * self vtableSize. functionPointer := Alien forPointer: (vtablePointer unsignedLongAt: (4 * Alien sizeofPointer + 1)). result := (Alien newGC: 4) pointer. functionPointer primFFICallResult: result with: self asJNIParameter. ^result signedIntAt: 1 ---- functionPointer is the pointer to the GetVersion function. The result should be 65542 (16r00010006), which is also what I get when calling the function from VisualWorks, but the method answers -394042288 (-16r177C9BB0). The "result" Alien has the printString '#[0 0 0 0 6 0 1 0]' which suspiciously contains the 1 and the 6 I am looking for, but in the wrong places. ;-) I looked at examples for callouts, which seem to indicate that result should be the Alien and not a pointer to it. So I changed the code to ---- result := (Alien newC: 4). functionPointer primFFICallResult: result pointer with: self asJNIParameter. ^result signedIntAt: 1 ---- This didn't really help. The result is now 0 (zero), although the Alien prints as #[252 255 255 255 80 15 38 0] which doesn't look like a 0 at first sight. Am I using those Aliens in a correct way? What can I try to debug this? If this is too obscure and someone who knows about Aliens would like to have a look at the rest of the code, I am willing to send a bunch of Monticello packages and instructions for reproducing the problem, but I won't make it publicly available yet. Any help is welcome. Best regards, Joachim Geidel -- View this message in context: http://forum.world.st/Need-help-with-Alien-unexpected-function-return-value-... Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.