[Mono-dev] internal call from c# to c++

[Erik Christensen]

Robert Jordan wrote:
> 
> Erik Christensen wrote:
>> Hi,
>> 
>> Trying to make a program, where it's possible to use C# to script to the
>> Core (C++ code).
>> 
>> I don't want to use P/Invoke.
>> 
>> I can run the Internal calls  example from 
>> http://http://www.mono-project.com/Embedding_Mono
>> http://www.mono-project.com/Embedding_Mono  without a problem. And
>> everything's fine as long as the function(s) doesn't use any argument(s).
>> However, I just can't seem to get a hold of the arguments on the C++
>> side.
>> Can someone pass an advice on this please?
>> 
>> Testcode is:
>> 
>> **************
>> C# :
>> **************
>> using System;
>> using System.Runtime.CompilerServices;
>> 
>> class Test
>> {
>> 
>> [MethodImplAttribute(MethodImplOptions.InternalCall)]
>>     extern private int calcsum(int a, int b);
>> 
>> static void Main(string[] args)
>>     {
>>         Test t = new Test();
>>         Console.Write(t.calcsum(3,3));
>>     }
>> }
>> 
>> 
>> **************
>> C++ : (mono embed)
>> **************
>> //include's
>> 
>> int calcsum(int a, int b)
>> {
>>    return (a+b);
>> }
>> 
>> int main(int argc, char* argv[]) 
>> {
>> 
>> //...
>> 
>> mono_add_internal_call ("Test::calcsum(int,int)", calcsum);
>> 
>> //...
>> }
>> 
>> It'll compile, and run, however the result is just random numbers from
>> somewhere in the memory, which should mean that the "a" and "b" variables
>> aren't set from the c# side (ie. the 3 is lost somewhere).
> 
> 
> Have a closer look at the signature:
> 
> [MethodImplAttribute(MethodImplOptions.InternalCall)]
>      extern private int calcsum(int a, int b);
> 
> This is an instance member, because "static" is missing.
> 
> In this case the C signature must be
> 
> int calcsum(void *obj, int a, int b)
> {
>     return (a+b);
> }
> 
> Of, if you want to access the MonoObject:
> 
> int calcsum(MonoObject *obj, int a, int b)
> {
>     return (a+b);
> }
> 
> If your methods are sematically rather static (like in your
> sample), just change the managed signature:
> 
> [MethodImplAttribute(MethodImplOptions.InternalCall)]
>      static
>      extern private int calcsum(int a, int b);
> 
> Robert
> 
> _______________________________________________
> Mono-devel-list mailing list
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> 
> 

Thanks a lot!

And the added access to the object is just splendid (need it later on).
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