DLL call in Smalltalk

[Gaurav Sharma]

Hi,

I was going through the smalltalk code and found something a bit strange, look below -

 

"<primitive: VMprBlockContextValueOnReturnDo>"

 

I check the code and VMprBlockContextValueOnReturnDo returned a value of 181 on inspecting but could not find anything by the name primitive: aString.

What I could grasp was that this is a call to some DLL but how is the call happening and which DLL is it calling was something I could not trace.

 

Can anyone help me with this? maybe redirect me to the correct doc

 

Thanks

[Marten Feldtmann]

A primitive is a very special call to a native external library code.

After all its an exported external function from a shared library therefore you might look at the exported functions of some of the dlls delivered with VASmalltalk.

In this example perhaps the dll containing the virtual machine.

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[John O'Keefe]

Marten is exactly correct, but I will add a little additional information.

 

If the external function is located in a DLL/shared object other than the VM, then the name of the DLL/shared object will be specified (i.e. <primitive: Foo:Entry-point name>; if it is the VM, only the Entry-point name is specified (as in your example).

 

You may also find constructs that look like <c: Foo:Entry-point name> and wonder how these are different from primitives.  The implementation of <primitive: ...> takes Smalltalk objects as parameters and return a Smalltalk object as the result; the implementation of <c: ...> takes normal C parameters and answers a normal C result.

 

You can find a lot more detail on the subject at VA Smalltalk Virtual Machine API.

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[Gaurav Sharma]

Thanks John for the additional info, this is exactly what i was looking for... 

[Marten Feldtmann]

You may view the screencasts I've done about this topic:


http://smalltalkinspect.podspot.de/post/msc010-vasmalltalk-c-api-part-07-en/

http://smalltalkinspect.podspot.de/post/msc009-c-api-08m4v-en/