SystemC 01 Hello World

Two approaches to print a string to console

1. c++ style: print from a normal c++ function
2. systemc style: print from a systemC method invoked by systemC simulation kernel

Before we start, you need to know some basics.

SystemC header file

To use the SystemC class library features, an application shall include either of the C++ header files specified below:

1. #include <systemc.h> a) systemc.h add all of the names from the namespaces sc_core and sc_dt to the declarative region in which it is included, together with the name sc_unnamed and selected names from the standard C or C++ libraries (e.g. cin, cout, iostream). b) systemc.h is provided for backward compatibility with earlier versions of SystemC and may be deprecated in future versions of this standard.
2. #include <systemc>
   1. systemc is the old systemc.h without usings
   2. A common practice is to include <systemc>, followed by using namespace sc_core. The programmer can then include other namespaces on a need basis.

SystemC entry point

• while a normal c++ program’s entry point is the main() function, systemC user has to use int_sc_main(int argc, char* argv[]) as the entry point.
• This is because systemC library has the main() function already defined. main() will call sc_main() and passes the command-line parameters.

SystemC module

• a systemC module is a class (or struct) that inherits the sc_module base class. This will be discussed in upcoming examples.

Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

// Learn with Examples, 2020, MIT license
#include <systemc> // include the systemC header file
using namespace sc_core; // use namespace

void hello1() { // a normal c++ function
  std::cout << "Hello world using approach 1" << std::endl;
}

struct HelloWorld : sc_module { // define a systemC module
  SC_CTOR(HelloWorld) {// constructor function, to be explained later
    SC_METHOD(hello2); // register a member function to the kernel
  }
  void hello2(void) { // a function for systemC simulation kernel, void inside () can be omitted
    std::cout << "Hello world using approach 2" << std::endl;
  }
};

int sc_main(int, char*[]) { // entry point
  hello1(); // approach #1: manually invoke a normal function
  HelloWorld helloworld("helloworld"); // approach #2, instantiate a systemC module
  sc_start(); // let systemC simulation kernel to invoke helloworld.hello2();
  return 0;
}

// Result
//from hello1()
Hello world using approach 1
//from hello2()
Hello world using approach 2

Reference

• SystemC Tutorials
• Learn SystemC with Examples