System C

This repository contains basic hardware modeling projects implemented using SystemC.

---

What is SystemC?

SystemC is a C++ class library and simulation kernel used for modeling and simulating hardware systems at various abstraction levels. It is widely used in:

• Electronic System Level (ESL) design
• Functional and behavioral modeling
• Hardware/software co-design
• Supports concurrent process modeling like Verilog/VHDL.
• Can simulate timing and concurrency.
• Allows modular and hierarchical design.

SystemC allows designers to write and simulate hardware designs using standard C++ syntax, making it a powerful tool for pre-silicon verification and architectural modeling.

---

Key Concepts of SystemC

Module (sc_module)

Basic building block representing hardware components or systems.

SC_MODULE (Modname) {
  SC_CTOR (Modname) {
     //Declare Process
  }
};

Constructor (SC_CTOR)

• Initializes the module
• Registers the process (SC_METHOD, SC_THREAD, SC_CTHREAD)
• Build ports to signals
• Called once at the beginning of the simulation.

Destructor (~ModuleName())

• Optional
• Cleans up resources (like file handles or dynamic memory)
• Called after the simulation ends or the object is detected.

SC_MODULE(Modname) {  
 SC_CTOR(Modname) {  //Constructor
  SC_METHOD(process);
  sensitive << clk.pos();
  cout << " Constructor is called. \n" << endl;
}

~Modname() { // Destructor
  cout << "Destructor is called. \n" << endl;
}

void process () {
  //Process logic
 }
};

Processes

• Functions that define the behavior of modules. Three types of processes are available in SystemC:

SC_METHOD:

• Runs instantly.
• No internal wait or zero delay
• Sensitive to signals/events.

SC_THREAD:

• Can include wait() statement
• Models sequential behavior.
• Supports delays.

SC_CTHREAD:

• Clocked thread process
• Triggered on clock edges.

Ports and Interfaces

Used for communication between modules; defines inputs and outputs.

sc_in -> Input port.

sc_out -> Output port.

sc_signal -> Signal for communication.

sc_clock -> Clock signal.

Channels

• Communication mechanisms between modules (e.g., signals, FIFOs).

Events and Sensitivity

• Processes can be triggered by changes in signals or explicit events.
• SystemC uses simulation time to model hardware behavior.

sc_start() -> Starts the simulation.

wait() -> Used in threads to suspend or resume.

sc_time() -> Defines specific time units ( eg," sc_time (10, SC_NS) ).

SC_ZERO_TIME -> Zero time constant.

Simulation Kernel

• Manages execution and scheduling processes based on events and time.

Hierarchical Design

• Modules can be instantiated under different modules to create a hierarchical system design.

SC_MODULE (TOP) {
  submodule sub1;
  SC_CTOR (TOP): sub1 ("sub1") {
    sub1.in(signal_in);
    sub1.out(signal_out);
 } 
};

Tracing and Debugging

• Use " sc_trace () " to record signal values during simulation.

sc_trace_file* tf = sc_create_vcd_trace_file ("wave");
sc_trace (tf, signal_name. "signal_label");
sc_close_vcd_trace_file(tf);

DataTypes

1. sc_int: Signed Integer with "n" bits.
2. sc_uint: Unsigned Integer with "n" bits.
3. sc_bigint: Larger Signed Integer with "n" bits.
4. sc_logic: Supports 4-valued logic: 0, 1, X, Z.
5. sc_fixed: Fixed-point numbers.

sc_main () Function

• The main function in SystemC.

int sc_main(int argc, char* argv[]) {
   sc_start(10, SC_NS);
   return 0;
}

Testbench

int sc_main (int argc, char* argv[]) {
  sc_signal<bool> a,b,y;
  AND and1 ("and1");
  and1.a(a);
  and1.b(b);
  and1.y(y);

  a = 1, b = 0;
  sc_start(1, SC_NS);
  cout << "AND: " <<y.read() <<endl;
  return 0;
}

## ⚙️ How to Install SystemC (Locally)

Follow the steps below to install **SystemC 2.3.3** on a Linux-based system:

### 1. Install required packages

```bash
sudo apt update
sudo apt install -y build-essential git cmake

2. Download and extract SystemC

mkdir -p $HOME/systemc
cd $HOME/systemc

wget https://www.accellera.org/images/downloads/standards/systemc/systemc-2.3.3.tar.gz
tar -xzf systemc-2.3.3.tar.gz
cd systemc-2.3.3

3. Build and install SystemC

mkdir objdir
cd objdir
../configure --prefix=$HOME/systemc/systemc-2.3.3-install
make -j$(nproc)
make install

4. Set environment variables

Add these to your ~/.bashrc or ~/.zshrc:

export SYSTEMC_HOME=$HOME/systemc/systemc-2.3.3-install
export LD_LIBRARY_PATH=$SYSTEMC_HOME/lib-linux64:$LD_LIBRARY_PATH
export CPLUS_INCLUDE_PATH=$SYSTEMC_HOME/include:$CPLUS_INCLUDE_PATH

Then apply the changes:

source ~/.bashrc

How to Run the Code

Option 1: Run Locally

You can compile and run any module using g++:

g++ -I$SYSTEMC_HOME/include -L$SYSTEMC_HOME/lib-linux64 \
    -o run_module folder/initiator.cpp folder/target.cpp folder/main.cpp \
    -lsystemc -lm
./run_module

Replace folder/ with the name of the subdirectory (e.g., ha, fa, counter).

Option 2: Run on EDA Playground

If you don't want to install SystemC locally, you can:

Use EDA Playground :

Select SystemC (IEEE 1666) as the simulator. Copy-paste your code into the editor. Run simulations online with waveform support.

~ Note: EDA Playground supports small-scale SystemC projects only.

Feel Free to Collaborate

Contributions are welcome! Whether you're fixing bugs, adding new modules, or improving documentation. Your input is appreciated.

Fork the repo, make changes, and open a pull request! Let’s make hardware modeling more accessible for everyone.

License

This project is intended for educational and academic purposes. Free to use and modify.