SystemC supports all C++ data types; in addition SystemC provides additional data types for describing hardware.Data types are explained in two parts,

1. C++ data types
2. SystemC data types

 C++ Data Types 

• Fundamental datatypes
• Additional datatypes

 Fundamental Data Types: 

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  //variable declaration
  int a;
  float b;
  float c;
  
  //initialization
  a = 10;
  b = 20.5;
  
  //addtion
  c = a + b;
  
  cout <<"Value of a = "<< c <<endl;
  
  // Terminate simulation
  return 0;
}

Value of a = 30.5
Execute the above code on 

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  
  //variable declaration and initialization
  //variables can be initialized in three different ways as shown below
  int   a=10;
  int   b(1.3);
  float c{2.8}; 
    
  cout <<"Value of a = "<< a <<endl;
  cout <<"Value of b = "<< b <<endl;
  cout <<"Value of c = "<< c <<endl;
  
  // Terminate simulation
  return 0;
}

Value of a = 10
Value of b = 1
Value of c = 2.8
Execute the above code on 

Example-3: Initializing char

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  
  //variable declaration and initialization
  char a[] = "Hello world";
  char b[5];

  //initialization
  b[0] = 'H';
  b[1] = 'e';
  b[2] = 'l';
  b[3] = 'l';
  b[4] = 'o';
  
  //below initializations types are not allowed
  //b = "Hello";
  //b = {'H','e','l','l','o'};
  
  cout <<"Value of a = "<< a <<endl;
  cout <<"Value of b = "<< b <<endl;
  
  // Terminate simulation
  return 0;
}

Simulator Output:

Value of a = Hello world
Value of b = Hello
Execute the above code on 

 

 

 Additional Data Types: 

• String Data Types
• Enumerated Data Types
• Typedef Data Types

String Types:

As Fundamental data types, we cant use the string data type directly. To use string data type need to import the string header standard library.( #include <string>)

 

Example-4: enum example

#include "systemc.h"
#include <string>
using namespace std;

int sc_main (int argc, char* argv[]) {
  
  //string declaration and initialization
  string mystring   = "Hello world";
  string mystring_1;
  string mystring_2;
  string mystring_3;
  
  //initialization, can be initialized in three ways.
  mystring_1 =  "1. I am String in C++/SystemC";
  mystring_2 = ("2. I am String in C++/SystemC");
  mystring_3 = {"3. I am String in C++/SystemC"};
  
  cout <<"mystring   = "<< mystring <<endl;
  cout <<"mystring_1 = "<< mystring_1 <<endl;
  cout <<"mystring_2 = "<< mystring_2 <<endl;
  cout <<"mystring_3 = "<< mystring_3 <<endl;
  
  // Terminate simulation
  return 0;
}

 

Simulator Output:

mystring_1 = 1. I am String in C++/SystemC
mystring_2 = 2. I am String in C++/SystemC
mystring_3 = 3. I am String in C++/SystemC
Execute the above code on 

Enumerated Types:

 

An enumerated type defines a set of named values. The simplest enumerated type declaration contains a list of constant names and one or more variables.enum type_name {value1,value2,…,valuen} object_names;

This creates the type type_name, which can take any of value1, value2, … ,valuen as value. Variables of this type can directly be instantiated as object_names.
In the following example, colors is defined to be variable of the Colors type that includes the members red, green, blue, yellow, white, black.

enum Colors { red, green, blue, yellow, white, black } Color_t;

Color_t can be used directly used as variable, but Colors is used as type to declare the variables.

Example-5: Enum Example

#include "systemc.h"

int sc_main (int argc, char* argv[]) {

  //declaration
  enum Colors { red, green, blue, yellow, white, black } Colors_t;
  Colors my_color;
  
  Colors_t = white;
  my_color = blue;
  
  cout <<"Colors_t   = "<< Colors_t <<endl;
  cout <<"mystring   = "<< my_color <<endl;
  
  // Terminate simulation
  return 0;
}

 

Simulator Output:

Colors_t = 4
mystring = 2
Execute the above code on 

The actual values are default to integers starting at 0 and then increase. in the above example by default variable will get default value of 0,1,2,3,4,5 respectively from  red.

The values can be set for the names and also values can be set for some of the names and not set for other names. A name without a value is automatically assigned an increment of the value of the previous name.

In the following example value is set for green = 2, yellow = 8.

enum Colors { red, green=2, blue, yellow=8, white, black };

Example-6: Enum Example

#include "systemc.h"

int sc_main (int argc, char* argv[]) {

  //declaration
  enum Colors { red, green=2, blue, yellow=8, white, black };
  Colors my_color;
  
  my_color = blue;
  cout <<"my_color value is = "<< my_color <<endl;

  my_color = black;
  cout <<"my_color value is = "<< my_color <<endl;
  
  // Terminate simulation
  return 0;
}

 

Simulator Output:

my_color value is = 3
my_color value is = 10
Execute the above code on 

 

Typedef Data Types:

 

The user can define a new type using typedef,

            typedef int integre_v;

            This can then be instantiated as:

                     integer_v var1;

                     integer_v var2;

#include "systemc.h"
const int seconds_per_minute = 60;

int sc_main (int argc, char* argv[]) {

  cout <<"1 minute = "<< seconds_per_minute << " seconds"<<endl;
  cout <<"8 minute = "<< 8*seconds_per_minute << " seconds"<<endl;
  
  // Terminate simulation
  return 0;
}

 Fixed-Precision Integer Types  

 Arbitrary Precision Integer Types 

 Arbitrary Width Bit Vectors 

 Logic Type 

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 SystemC Modules 

Modules are the building blocks of SystemC, It is a container class that  may contain data members, channel members, processes, instance of other modules and ports for communication.

Modules are extended from sc_module, in other words modules are the child classes of sc_module Class.
Example:

class module_name : public sc_module {
. . .
};

Also module may be created with use of the SC_MODULE macro as follows,

Example:
SC_MODULE( module_name ) {
……
};

Constructor

SC_CTOR macro declares the constructor, module must have SC_CTOR or it can have SC_HAS_PROCESS.(will see the SC_HAS_PROCESS in next chapters)

by default SC_CTOR macro has one argument which is the name of the module.

Example:
SC_MODULE( module_name ) {
SC_CTOR(module_name){ }
};

Constructor to initialize the module properties:

Module Instance:
Module instance can be created as below,
module_name instance_name(“instance_name”);

Example:
SC_MODULE( module_1 ) {

};
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 functions argument passing 

• pass by value
• pass by reference

 pass by value 

In argument pass by value, argument passing mechanism works by copying each argument into the subroutine area. if any changes to arguments with in the subroutine, those changes will not be visible outside the subroutine.

 Example-1:

#include "systemc.h"

//function sum
int sum (int x,int y)
{ 
  return x = x+y;
}

int sc_main (int argc, char* argv[]) {
  int x=20;
  int y=30;
  int z;
  
  //function call
  z=sum(x,y);
  
  //value of x,y and z
  cout <<"Value of x="<<x<<endl;  
  cout <<"Value of y="<<y<<endl; 
  cout <<"Value of z="<<z<<endl; 
  // Terminate simulation
  return 0;
}

 Simulator Output: 

Value of x=20
Value of y=30
Value of z=50
Execute the above code on 

  argument pass by reference 

 Example-2 

#include "systemc.h"

//function sum
int sum (int& x,int& y)
{ 
  return x = x+y;
}

int sc_main (int argc, char* argv[]) {
  int x=20;
  int y=30;
  int z;
  
  //function call
  z=sum(x,y);
  
  //value of x,y and z
  cout <<"Value of x="<<x<<endl;  
  cout <<"Value of y="<<y<<endl; 
  cout <<"Value of z="<<z<<endl; 
  // Terminate simulation
  return 0;
}

 Simulator Output: 

Value of x=50
Value of y=30
Value of z=50

Execute the above code on 

 const keyword 

 Example-3 

#include "systemc.h"

//function sum
int sum (const int& x,const int& y)
{ 
  return x = x+y;
}

int sc_main (int argc, char* argv[]) {
  int x=20;
  int y=30;
  int z;
  
  //function call
  z=sum(x,y);
  
  //value of x,y and z
  cout <<"Value of x="<<x<<endl;  
  cout <<"Value of y="<<y<<endl; 
  cout <<"Value of z="<<z<<endl; 
  // Terminate simulation
  return 0;
}

 Simulator Output: 

testbench.cpp: In function ‘int sum(const int&, const int&)’:
testbench.cpp: error: assignment of read-only reference ‘x’
Exit code expected: 0, received: 1
Execute the above code on 

 default argument values 

 Example-4 

The example below shows argument with default value.

#include "systemc.h"

//function sum
int sum (int x=10,int y=20)
{ 
  return x = x+y;
}

int sc_main (int argc, char* argv[]) {
  int z;
  
  //function takes defalut values for arguments
  z=sum();
  cout <<"Value of z="<<z<<endl; 
  
  //function takes default value for second argument
  z=sum(20);
  cout <<"Value of z="<<z<<endl; 

  // Terminate simulation
  return 0;
}

 Simulator Output: 

Value of z=30
Value of z=40
Execute the above code on 
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 Functions 

function is group of statements to perform the specific task.

Syntax:


type function_name (arguments) {
function_body;
}

Example-1:

#include "systemc.h"

//function add, to add two integer numbers
int add (int a,int b)
{
 return a+b; 
}

int sc_main (int argc, char* argv[]) {
  //declaration
  int x,y,z;
  
  //initialization
  x=10;
  y=20;
  
  //function calling
  z =  add(x,y);
  cout <<" x+y = "<<z<<endl;
    
  // Terminate simulation
  return 0;
}

Simulator Output:

x+y = 30
Execute the above code on 

 void functions 

Generally functions will return an value, where as void functions will not return any value.
by specifying type as void function can be declared as void function.

Example-1:

#include "systemc.h"

//function add, to add two integer numbers
void display (int a,int b)
{
 cout <<" recived a = "<<a<<" b = "<<b<<endl; 
}

int sc_main (int argc, char* argv[]) {
  
  //function calling
  display(10,20);
    
  // Terminate simulation
  return 0;
}

Simulator Output:

recived a = 10 b = 20
Execute the above code on 

 function call as expression 

Example-1:

#include "systemc.h"

//function add, to add two integer numbers
int add (int a,int b)
{
 return a+b; 
}

int sc_main (int argc, char* argv[]) {
  //declaration
  int x,y,z;
  
  //initialization
  x=10;
  y=20;
  
  //function call in expression
  z =  10 + add(x,y) + 20;
  cout <<" Value of z = "<<z<<endl;
    
  // Terminate simulation
  return 0;
}

Simulator Output:

Value of z = 60
Execute the above code on 

  functions declaration 

Example-1:

#include "systemc.h"

//function display_1
void display_1 ()
{
  display_2;
}

//function display_1
void display_2 ()
{
  display_1;
}

int sc_main (int argc, char* argv[]) {
    
  // Terminate simulation
  return 0;
}

Simulator Output:

testbench.cpp: In function ‘void display_1()’:
testbench.cpp: error: ‘display_2’ was not declared in this scope
Exit code expected: 0, received: 1

Execute the above code on 

Example-2:

#include "systemc.h"

void display_1();
void display_2();

//function display_1
void display_1 ()
{
  display_2();
}

//function display_1
void display_2 ()
{
  display_1();
}

int sc_main (int argc, char* argv[]) {
  cout <<"Inside Main"<<endl;
  // Terminate simulation
  return 0;
}

Simulator Output:

Inside Main
Execute the above code on 
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 Jump Statements: 

 break 

Execution of break statement leads to end of the loop.

Example-1: break

#include "systemc.h"
int sc_main (int argc, char* argv[]) {

  //break-example
  for(int i=0;i<8;i++) {
    cout <<" Value of i="<<i<<endl;
    if(i == 4) {
      cout <<" Calling break"<<endl;
      break;
    }
  }
           
  // Terminate simulation
  return 0;
}

Simulator Output:

j=0 i=4
j=1 i=3
j=2 i=2
j=3 i=1
Execute the above code on 

 continue 

Execution of continue statement leads to skip the execution of statements followed by continue and jump to next loop or iteration value.

Example-1: continue

#include "systemc.h"
int sc_main (int argc, char* argv[]) {

  //continue-example
  for(int i=0;i<5;i++) {
    cout <<"Before continue, value of i="<<i<<endl;
    if((i > 1) && (i < 4)) {
      cout <<"     Calling continue"<<endl;
      continue;
    }
    cout <<"After  continue, value of i="<<i<<endl;
  }
           
  // Terminate simulation
  return 0;
}

Simulator Output:

Before continue, value of i=0
After continue, value of i=0
Before continue, value of i=1
After continue, value of i=1
Before continue, value of i=2
Calling continue
Before continue, value of i=3
Calling continue
Before continue, value of i=4
After continue, value of i=4
Execute the above code on 

 goto 

Execution of goto leads to jump to another point in the program.

Example-1: goto

#include "systemc.h"
#include <iostream>
using namespace std;

int sc_main (int argc, char* argv[]) {
  //declaration and initialization
  int a = 15;
  int b = 10;
  
  my_lable:  
  cout <<" @ my_label "<<endl;

  if( a > b ) {
    cout <<" a is greater than b a = "<<a<<" b = "<<b<<endl;
    a--;
    goto my_lable;
  }
  else
    cout <<" b is greater than a "<<endl;
    
  // Terminate simulation
  return 0;
}

Simulator Output:

@ my_label
a is greater than b a = 15 b = 10
@ my_label
a is greater than b a = 14 b = 10
@ my_label
a is greater than b a = 13 b = 10
@ my_label
a is greater than b a = 12 b = 10
@ my_label
a is greater than b a = 11 b = 10
@ my_label
b is greater than a
Execute the above code on 
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 Statements 

{
    Statement1;
    Statement2;
    Statement3;
}

  if and else 

Below are the few examples,

//if, execution of one statement on condition satisfied

if ( condition ) statement;

//if, execution of block/statement's on condition satisfied
if ( condition ) {
    Statement1;
    Statement2;
}

//if along with else part
if(condition) {
     Statement1;
}
else {
      stetement2;
}

//if, with nested if in else part
if(condition2) {
     Statement1;
}
else  if (condition2) {
   if(condition3)  stetement2;
   else            statement3;
}

Example-1:

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  //declaration and initialization
  int a = 10;
  int b = 30;
  
  //if-else 
  if( a > b )
    cout <<" a is greater than b "<<endl;
  else
  {
    cout <<" b is greater than a "<<endl;
    if((b-a) > a)
      cout <<" b-a is greater than a"<<endl;
    else 
      cout <<" b-a is less than a "<<endl;
  }
    
  // Terminate simulation
  return 0;
}

Simulator Output:

b is greater than a
b-a is greater than a

Execute the above code on 

 Loop Statements: 

Below are the loop statements in C++/SystemC,

• For Loop
• While Loop
• Do-while

 for loop 

• Initialize the loop variable
• Check for the condition, if condition is satisfied then executes the block
• Increment/decrement the loop variable value

Example-1: for-loop

#include "systemc.h"
int sc_main (int argc, char* argv[]) {

  //for-loop
  for(int i=0; i<4; i++)
  {
    cout <<" Value of i = "<<i<<endl;
  }
    
  // Terminate simulation
  return 0;
}

Simulator Output:

Value of i = 0
Value of i = 1
Value of i = 2
Value of i = 3
Execute the above code on 

Example-2: for-loop, one or more initial declaration

#include "systemc.h"
int sc_main (int argc, char* argv[]) {

  //for-loop
  for ( int j=0,i=3;j<5;j++)
  {
    if(j==i) 
      cout <<" Value j equals to Value of i. j="<<j<<" i="<<i<<endl;
     else
      cout <<" Value j ="<<j<<endl;
  }
    
  // Terminate simulation
  return 0;
}

Simulator Output:

Value j =0
Value j =1
Value j =2
Value j equals to Value of i. j=3 i=3
Value j =4
Execute the above code on 

Example-3: for-loop, one or more step assignment

#include "systemc.h"
int sc_main (int argc, char* argv[]) {

  //for-loop
  for ( int j=0,i=4;j<4;j++,i--)
  {
    cout <<" j="<<j<<" i="<<i<<endl;
  }
    
  // Terminate simulation
  return 0;
}

Simulator Output:

j=0 i=4
j=1 i=3
j=2 i=2
j=3 i=1
Execute the above code on 

 While Loop 

Example-1: while-loop

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  //declaration and initialization
  int a = 15;
  int b = 10;

  //while-loop
  while( a > b ) {
    cout <<" a is greater than b a = "<<a<<" b = "<<b<<endl;
    a--;
  }

  cout <<" b is greater than a "<<endl;
    
  // Terminate simulation
  return 0;
}

Simulator Output:

a is greater than b a = 15 b = 10
a is greater than b a = 14 b = 10
a is greater than b a = 13 b = 10
a is greater than b a = 12 b = 10
a is greater than b a = 11 b = 10
b is greater than a
Execute the above code on 

 Do-while 

Example-1: do-while

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  //declaration and initialization
  int a = 9;
  int b = 10;

  //while-loop
  do{
    cout <<" a is greater than b a = "<<a<<" b = "<<b<<endl;
    a--;
  }while( a > b );

  cout <<" b is greater than a "<<endl;
    
  // Terminate simulation
  return 0;
}

Simulator Output:

a is greater than b a = 9 b = 10
b is greater than a
Execute the above code on 
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 Arithmetic Operators 

 

Example-1: Addition Operator

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 10;
  int b = 20;
  int c;
  
  //addition operator,
  c = a + b;
  
  cout <<"Value of c = " << c << endl;
  return 0;// Terminate simulation
}

Simulator Output:

Value of c = 30

Execute the above code on 

 Increment and Decrement 

Operator	Description
++	Increment	Increment the operand by one and store the result in the operand.
—	Decrement	Decrement the operand by one and store the result in the operand.

Pre Increment and Pre Decrement:

In Pre Increment/Decrement, operator is specified before the operand.

The pre increment/decrement performs the operation first and returns the new value.

Post Increment and Post Decrement:

In Post Increment/Decrement, operator is specified after the operand.

The post increment/decrement  returns the old value while the new value of the operation is stored in the operand.

Example-1: Pre-Increment

 

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 5;

  //pre-increment
  cout <<"Value of a = " << ++a << endl;
  return 0;// Terminate simulation
}

Simulator Output:

Value of a = 6
Execute the above code on 

Example-2: Post-Increment

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 5;

  cout <<"Value of a = " << a++ << endl;
  return 0;// Terminate simulation
}

Simulator Output:

Value of a = 5
Execute the above code on 

 Bitwise Operators 

 

Operator	Description
&	AND operator	Calculate the bitwise AND of the two operands.
|	OR  operator	Calculate the bitwise OR of the two operands.
^	XOR operator	Calculate the bitwise XOR of the two operands.

 

Example-1: Bitwise AND Operator

 

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 1;
  int b = 1;
  int c;
  
  //bitwise AND operator,
  c = a & b;
  
  cout <<"Value of c = " << c << endl;
  return 0;// Terminate simulation
}

Simulator Output:

Value of c = 1

 

Execute the above code on 

 Arithmetic and Bitwise assignment 

Operator	Description
+=	Add the two operands; assign the result to the first operand.
-=	Subtract the second operand from the first operand; assign the result to the first operand.
*=	Multiply the two operands; assign the result to the first operand.
/=	Divide the first operand by the second operand; assign the result to the first operand.
%=	Modulo operation; assign the result to the first operand.
&=	Calculate the bitwise AND of the two operands; assign the result to the first operand.
|=	Calculate the bitwise OR of the two operands; assign the result to the first operand.
^=	Calculate the bitwise XOR of the two operands; assign the result to the first operand.

Example-1: += Operator

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 10;
  int b = 20;
  
  //+= operator, Arithmetic and bitwise assignment
  a += b;
  
  cout <<"Value of a = " << a << endl;
  return 0;// Terminate simulation
}

Simulator Output:

Value of a = 30
Execute the above code on 

Example-2: &= Operator

 

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 1;
  int b = 0;
  
  //&= operator, Arithmetic and bitwise assignment
  a &= b;
  
  cout <<"Value of a = " << a << endl;
  return 0;// Terminate simulation
}

Simulator Output:

Value of a = 0
Execute the above code on 

 Equality and Relation 

Operator	Description
==	equal	Return true if the operands are equal.
!=	not equal	Return true if the operands are not equal.
<	less than	Return true if the first operand is less than the second operand.
<=	less than or equal to	Return true if the first operand is less than or equal to the second operand.
>	greater than	Return true if the first operand is greater than the second operand.
>=	greater than or equal to	Return true if the first operand is greater than or equal to the second operand.

#include "systemc.h"
int sc_main (int argc, char* argv[]) {
  int a = 10;
  int b = 20;
  
  // == operator, Equality and relation 
  if(a == b)  
    cout <<"a is equals to b"<< endl;
  else
    cout <<"a is not equals to b"<< endl;
  return 0;// Terminate simulation
}

a is not equals to b
Execute the above code on 

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