Passing user defined object as a parameter for sc_fifo

[jinhuang12]

Hello, I want to make a server module that outputs a user defined class through sc_fifo and I'm not sure if that is possible.  So far, I have this 

 

Server module header

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

#include <systemc.h>

#include "Gaze.h"

#include "ImageObjects.h"

#include "Image.h"

#include "iostream.h"

#include "fstream.h"

#include "string.h"

#include <sstream>

 

SC_MODULE(Server)

{

    //PORTS FOR SERVER

    sc_in_clk clk; //Clock

    sc_in<sc_uint<8> > check; //Signal for client to request new image

    sc_port<sc_fifo_in<Gaze >> inClient; // input from client

    sc_port<sc_fifo_out<Image >> output; //output to client

    

    void sendImage(sc_uint<8> img); //Function to send image to client

    std::vector<Image> getImages(); //Takes in annotation files and saves them as images

    

    //Local data structures

    std::vector<Image> ImageBuffer;

    

    SC_CTOR(Server)

    {

        SC_METHOD(sendImage);

            sensitive << check;

    }

    

};

------------------------------------------------------------------------------------------------------------------------------------------------------------------------

 

Would "sc_port<sc_fifo_out<Image >> output;" that line of code work?

 

Image is just a class I created in c++

------------------------------------------------------------------------------------------------------------------------------------------------------------------------

#include "ImageObjects.h"

#include <vector>

 

class Image : public sc_interface

{

    

public:

    

    int imageNumber;

    std::vector<ImageObjects> obj;

    

   

    Image(int i, std::vector<ImageObjects> ob);

    //void setImage(int, Objects[]);

    virtual Image returnImage();

    

};

---------------------------------------------------------------------------------------------------------------------------------------------

 

 

Thanks for all the help!

 

 

[maehne]

sc_fifo_in and sc_fifo_out are already specialized ports to be connected to an sc_fifo. So, you don't need to put them as a template argument to sc_port<IF>. Regarding what kind of operations a user-defined type has to support to be communicated through an sc_fifo, have a look to clause 6.23.3 in the freely available IEEE Std 1666-2011. Basically, the output stream operator<<, an assignment operator=, and a default constructor have to be defined for that it can work.

[jinhuang12]

Thank you for the reply, so in order for me to pass an Image over sc_fifo, would I have to change my Image class code to something like this?

 

template <typename T>
class Image;

template <typename T>
ostream& operator<<(ostream &, const Image<T> &);

template<typename T>
class Image
{
public:
friend ostream& operator<< <>(ostream & output, const Image<T> & theImage);
...
};

template<typename T>
ostream& operator<<(ostream & output, const Image<T> & theImage)
{
...
return output;
}

 

Can you show an example of how I would use the assignment operator and would I have to change the Image.cpp file to accommodate this change?

 

Image.cpp

________________________________________________________________________________________________________________________________________________________________________________________

#include "Image.h"

 

//void Image::setImage(int imageNumber, Objects objects[])

//{

//    this->imageNumber = imageNumber;

//    

//    int i = 0;

//    while (i < sizeof(*objects))

//    {

//        this->objects = objects;

//        i++;

//    }

//    

//}

 

Image::Image(int imageNumber, std::vector<ImageObjects> obj)

{

    this->imageNumber = imageNumber;

    this->obj = obj;

} 

 

____________________________________________________________________________________________________________________________________________________________________________________________

 

Thanks again!

[maehne]

The assignment operator just implements the copy operation when you want to assign the value of a variable to another one of the same type. By default, C++ generates a copy constructor and assignment operator, which will simply use member-wise assignment. This usually won't be enough if you use internally pointers and dynamic memory allocation.

 

The sc_fifo uses the assignment operation to copy the value passed into its input into the internal buffer of the FIFO.

 

Have a look to the Doulos FAQ on SystemC to know more about how to use user-defined data types with SystemC channels:

http://www.doulos.com/knowhow/systemc/faq/#q1

 

For examples how to implement correctly the copy constructor and assignment operation, have a look into a good C++ book or the C++ FAQ. Here are some helpful URLs:

http://www.isocpp.org/

http://www.cplusplus.com

http://www.parashift.com/c++-faq/

[jinhuang12]

Okay thanks again, and one more question if you dont mind, are vectors allowed to be used in a sc_module as a data structure?

[apfitch]

sc_module is just a c++ class, so it can have data members of type vector,

 

regards

Alan