Kernel Class with Default Constructor - 2025.2 English - UG1483

Vitis Model Composer User Guide (UG1483)
Document ID
UG1483
Release Date
2025-11-20
Version
2025.2 English

As an example, to import the C++ class kernel with the default constructor, consider the following simple.h header file that defines the kernel class simple_class with the default constructor.

simple.h 


#include "adf.h"

using namespace adf;

class simple_class
{
private:
 int16 val;
 int16 numSamples;

public:
 simple_class();
 void mulBytwo(input_buffer<int16> & in, output_buffer<int16> & out);

 static void registerKernelClass()
 {
    REGISTER_FUNCTION(simple_class::mulBytwo);
 }
};
Recommended: It is highly recommended to define the body of the kernel and class constructors in .cpp file.

You must register the kernel function using the registerKernelClass() method. More than one class kernel can be declared in a header file and each class must contain separate registerKernelClass() methods. You can register only one function per class and Vitis Model Composer can import only functions that are registered using REGISTER_FUNCTION().

The Kernel function is defined in simple.cpp as shown below.

simple.cpp 

#include "simple.h"

simple_class::Simple_class()
{
 val = 24;
 numSamples = 8;
}

void simple_class::mulBytwo(input_buffer<int16> & in, output_buffer<int16> & out)
{
    auto pIn  = aie::begin(in);
    auto pOut = aie::begin(out);
        
    for (int i=0; i<numSamples; i++)
    {
        *pOut++ = 2*(*pIn++) + val;
    }
}

To import the mulBytwo function as a block in a Vitis Model Composer design, double-click the AIE Class Kernel block. Then update the parameters as follows:

Kernel header file
simple.h
Kernel class
simple_class
Kernel function
mulBytwo
Kernel source file
simple.cpp
Kernel search path
Leave empty
Preprocessor options
Leave empty

Click the Import button in the Block Parameters dialog box. After successful import, the Function tab displays. This provides user-editable configuration parameters as shown in the following figure.

Figure 1. AIE Class Kernel: Block Parameters

After entering the appropriate values in the Function tab, click Apply to see the updated interface of the AIE Class Kernel block GUI as shown.

Figure 2. AIE Class Kernel after Update

You can quickly review the function declaration of the imported kernel function and the port names with directions, from the Function tab.

Click the Kernel Class tab to observe the class declaration as shown in the following figure.

Figure 3. Kernel Class Tab: Class Declaration