Integrating C++ and C# code
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Hi, I'm working on a project in which I have the GUI and audio I/O programmed in C# .NET (and DirectSound using C#), and the DSP algorithms programmed in Visual C++. I have no experience in integrating code written in these two languages. Am I correct in understanding that Visual C++ code in a C# program is called Managed C++. Could anybody give me links to pages that deal with this issue in detail? Thanks!
Not quite. Managed C++ is just C++ code with the managed extensions enables. that means that it's C++ that does the garbage collecting and can call into the .Net framework. You can load up a DLL and call functions from it in your C# code. This will involve marshalling your data back and forth between the managed C# code and the unmanaged C++. What you want to do is to call normal C++ or unsafe code from inside of your C# code. Here is one article on it, but you can also search for unsafe code in C# and you should be able to find more. You can also look for C# and marshalling for more. Mixing Managed and Unmanaged code Steve Maier, MCSD MCAD
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Hi, I'm working on a project in which I have the GUI and audio I/O programmed in C# .NET (and DirectSound using C#), and the DSP algorithms programmed in Visual C++. I have no experience in integrating code written in these two languages. Am I correct in understanding that Visual C++ code in a C# program is called Managed C++. Could anybody give me links to pages that deal with this issue in detail? Thanks!
That is a rather broad topic, depending on what type of integration you are looking for. Managed C++ is an extension of C++ that target's the CLR, however you can also perform mixed mode compilation to mix both managed and unmanaged code (
#pragma managedand#pragma unmanaged). Are you having specific problems getting your application to *talk* to each other across the language boundary? - Nick Parker
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Not quite. Managed C++ is just C++ code with the managed extensions enables. that means that it's C++ that does the garbage collecting and can call into the .Net framework. You can load up a DLL and call functions from it in your C# code. This will involve marshalling your data back and forth between the managed C# code and the unmanaged C++. What you want to do is to call normal C++ or unsafe code from inside of your C# code. Here is one article on it, but you can also search for unsafe code in C# and you should be able to find more. You can also look for C# and marshalling for more. Mixing Managed and Unmanaged code Steve Maier, MCSD MCAD
Why should he lookup unsafe code in C#? This is a grossly overused feature of C# and the CLI in general and is almost never necessary. It really only improves performance in walking memory (array iteration, image manipulation, etc.). It's not necessary for marshaling at all. Effective use of the
MarshalAsAttributeand a good understanding of unmanaged and managed types will help ensure you'll never need unsafe code. Another good reference is in the .NET Framework SDK itself. Read Interoperating with Unmanaged Code[^] in the .NET Framework SDK documentation. There's information about COM interop, P/Invoke, and marshalling.Software Design Engineer Developer Division Sustained Engineering, Microsoft My Articles
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That is a rather broad topic, depending on what type of integration you are looking for. Managed C++ is an extension of C++ that target's the CLR, however you can also perform mixed mode compilation to mix both managed and unmanaged code (
#pragma managedand#pragma unmanaged). Are you having specific problems getting your application to *talk* to each other across the language boundary? - Nick Parker
My Blog | My ArticlesFirstly, thank you all for your replies! Heath, I'll go over the link to the SDK documentation now. Considering that most DSP routines require a lot of array iteration and manipulation would unsafe code improve my program's performance? Nick, I don't have any specific problems just yet as I haven't started integrating (what is the correct term? I might be using the wrong terms here) the C++ code into the C# code. I'm sure I'll have a ton of problems once I do start :) I was just trying to ensure that I started down the right track.
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Firstly, thank you all for your replies! Heath, I'll go over the link to the SDK documentation now. Considering that most DSP routines require a lot of array iteration and manipulation would unsafe code improve my program's performance? Nick, I don't have any specific problems just yet as I haven't started integrating (what is the correct term? I might be using the wrong terms here) the C++ code into the C# code. I'm sure I'll have a ton of problems once I do start :) I was just trying to ensure that I started down the right track.
crushinghellhammer wrote: Considering that most DSP routines require a lot of array iteration and manipulation would unsafe code improve my program's performance? More than likely, yes, but I wouldn't recommend writing your DSP in managed code. For one, you need a shim (using regasm.exe will automatically register mscoree.dll as the shim, which marshals calls to your assembly). This requires that the CLR and any dependent assemblies be loaded and JIT'd as need (which means an initially longer load time). It's probably best to stick with native code to write your DSP.
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crushinghellhammer wrote: Considering that most DSP routines require a lot of array iteration and manipulation would unsafe code improve my program's performance? More than likely, yes, but I wouldn't recommend writing your DSP in managed code. For one, you need a shim (using regasm.exe will automatically register mscoree.dll as the shim, which marshals calls to your assembly). This requires that the CLR and any dependent assemblies be loaded and JIT'd as need (which means an initially longer load time). It's probably best to stick with native code to write your DSP.
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My DSP code is in Visual C++ and has no code written in assembler. However, I have used pointers extensively. Would using such code with my C# code qualify it as "unsafe" or "unmanaged" code?
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My DSP code is in Visual C++ and has no code written in assembler. However, I have used pointers extensively. Would using such code with my C# code qualify it as "unsafe" or "unmanaged" code?
What exactly are you trying to do? C# is one of many languages that target the CLR. Managed C++ (targets the CLR and has equal access to .NET assemblies, as well as native APIs) is another. But VC++ (unmanaged) is entirely different. When you expose your DSP as a COM control (which it already is by nature), you're merely using it in your C# project. I really don't understand what your problem is. If your DSP is written in VC++, then what are you trying to do in managed code (i.e., C#). If you're trying to use it, you declare the interfaces (as you have) and have to be able to instantiate the object. If your DSP has a typelib, you can use tlbimp.exe to generate an RCW (Runtime Callable Wrapper) or in Visual Studio .NET select Add Reference, click on the COM tab and either find your typelib in the list (if registered properly) or click the Browse button to find it. Either way will generate an interop library (the RCW) then you just use it.
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My DSP code is in Visual C++ and has no code written in assembler. However, I have used pointers extensively. Would using such code with my C# code qualify it as "unsafe" or "unmanaged" code?
What are you trying to accomplish? If it is the part of the DSP processing that is interfacing to the hardware I would be inclined to leave it C++. If it an application to help control the DPS process that might be worth writing in C#. It is all about a sensible system framework. If your C++ libraries are tangled together in pointers it might not be feasible at all to put into C#. If on the other hand system is segmented clearly and easily broken appart then that will help interop a lot.
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What exactly are you trying to do? C# is one of many languages that target the CLR. Managed C++ (targets the CLR and has equal access to .NET assemblies, as well as native APIs) is another. But VC++ (unmanaged) is entirely different. When you expose your DSP as a COM control (which it already is by nature), you're merely using it in your C# project. I really don't understand what your problem is. If your DSP is written in VC++, then what are you trying to do in managed code (i.e., C#). If you're trying to use it, you declare the interfaces (as you have) and have to be able to instantiate the object. If your DSP has a typelib, you can use tlbimp.exe to generate an RCW (Runtime Callable Wrapper) or in Visual Studio .NET select Add Reference, click on the COM tab and either find your typelib in the list (if registered properly) or click the Browse button to find it. Either way will generate an interop library (the RCW) then you just use it.
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What I'm trying to do is this: I have an application that I've written in C# using DirectSound. It allows for PLAYBACK of a pre-recorded .wav file, RECORDING of a .wav file and STREAMING of audio input from the soundcard. Now, I would like to be able to process this audio input by sending the audio data through a DSP routine. My DSP routines are coded in C++. My signal flow would be as follows: *input* -> DSP routine -> *output* The input and output have already been implemented in C# .NET. The DSP routine has been coded in C++. I could write it in C# if I absolutely HAD to, but I'm trying to avoid that. What is the best way to get this working?
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What I'm trying to do is this: I have an application that I've written in C# using DirectSound. It allows for PLAYBACK of a pre-recorded .wav file, RECORDING of a .wav file and STREAMING of audio input from the soundcard. Now, I would like to be able to process this audio input by sending the audio data through a DSP routine. My DSP routines are coded in C++. My signal flow would be as follows: *input* -> DSP routine -> *output* The input and output have already been implemented in C# .NET. The DSP routine has been coded in C++. I could write it in C# if I absolutely HAD to, but I'm trying to avoid that. What is the best way to get this working?
Depends - is the DSP a COM object or exported functions (perhaps even a class - but that gets more complicated; see the
CallingConvention.ThisCallfor details - and you'll need to implement an exported class factory function). If it's COM, declare your RCW (don't forget all the attributes:ComImportAttribute,GuidAttribute, etc.), or use tlbimp.exe or VS.NET's Add Reference if you're COM server has a typelib (or you have a detached typelib). If you're using exported functions, you'll need to use P/Invoke (seeDllImportAttribute) to call the functions. WithCallingConvention.ThisCall, you declare your functions with an extra parameter (the first parameter!) that is anIntPtr, which is a handle to your object. You should also define and export a class factory function, as well as a destruction function to tear-down the object. See a previous reply I wrote for more details aboutThisCall: http://www.codeproject.com/script/comments/forums.asp?msg=771919&forumid=1649#xx771919xx[^].Software Design Engineer Developer Division Sustained Engineering, Microsoft My Articles