MATLAB: Using mcc to compile a code that uses a .dll library

MATLABmcc compile .h .dll header

Hi,

I created a program in matlab with a GUI. I want to compile it to have an EXE. In the code, I use an external library, but I only have the files: foo.dll foo.h foo.lib.

In the matlab code I call: loadlibrary ('\foo', '\foo.h');

Later, I call some functions of those libraries, using: calllib('foo', 'Function', param);

I compile it using: mcc -m mycode.m -c

The compiler returns no errors, and a "mycode.exe" file is created. However, when I execute I get:

Error using loadlibrary (line 239) Deployed applications must use a prototype file instead of a header file. To create the prototype, use the loadlibrary mfilename option. Use the prototype file in compiled code. See http://www.mathworks.com/access/helpdesk/help/toolbox/compiler/brb8oui.html for more information.

Error in mycode>mycode_OpeningFcn (line 66)

Error in gui_mainfcn (line 221)

Error in mycode (line 42)

Do you have any tip on how I can overcome this?

Thank you.

Best Answer

As the error message suggests, you cannot use a header file (.h) with loadlibrary in deployment mode. The link in the error: http://www.mathworks.com/help/toolbox/compiler/brb8oui.html provides step-by-step instructions on how you can generate a MATLAB prototype file (.m) and replace the .h file in your loadlibrary command with the generated .m file. The will fix the error and is also more efficient than providing a .h file. See here for more information about using prototype files with loadlibrary.

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MATLAB: How to call loadlibrary in a compiled application by MATLAB Compiler on Windows

There are two steps necessary in order to successfully deploy an application which uses the loadlibrary command.

1.) Create a prototype m-file

When deploying loadlibrary you have to create a prototype m-file and use that instead of a header file.

Let us assume you call loadlibrary like this

loadlibrary(library, header)

You would then need to call loadlibrary once like this in MATLAB in order to create a prototype m-file:

loadlibrary(library, header, 'mfilename', 'PrototypeName');

After the execution you will see that a PrototypeName.m file was created in the current folder. In the case you use a 64bit MATLAB you will also notice that a library_thunk_pcwin64.dll was created in addition. We will also need that file later one (64bit only).

After you created the prototype m–file you need to adjust the call to loadlibrary to be:

loadlibrary(library, @PrototypeName)

2.) Compile the application

When compiling the application you have to decide if you like to compile the library into the application or to ship it externally.

2.1) Compiling the library into the application

When you like to compile the DLL into the application you have to add the library as shared resource or helper file manually. You can do this with the -a option (if using the mcc command) or by dragging it under Other/Additional Files (as a helper file) if using one of the compiler apps. In addition when working with 64bit MATLAB you also have to include the library_thunk_pcwin64.dll manually.

2.2) Providing the library as external file

When you decide not to include the library into the application you can also copy the library in the same folder as the compiled application without the need to adjust your code. When working with 64bit, you have to compile the library_thunk_pcwin64.dll into the application. Otherwise the library_thunk_pcwin64.dll cannot be found at runtime resulting in a module not found error.

The benefit of this approach is that you can replace the library with a newer version without the need to recompile the whole MATLAB application. BUT replacing the library with a different version works only if the function signatures of the function in the library stay the same because the prototype m-file (and the library_thunk_pcwin64.dll on 64bit) is tied to the function signatures of the functions in the library.

MATLAB: Can’t get Matlab compiler and loadlibrary to work

I suspect the correct reference page is here (I'll report the missing link as a bug).

From that reference page, it appears that you have the general workflow correct. I do notice that your LOADLIBRARY call includes both the header and the alias. Can you try calls like shown in the reference page, where the header is only included in the call in MATLAB but not in your deployed application?

Best Answer

Related Solutions

MATLAB: How to call loadlibrary in a compiled application by MATLAB Compiler on Windows

MATLAB: Can’t get Matlab compiler and loadlibrary to work

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