SystemC Fundamentals

SystemC is a C++ library for system-level modeling and hardware description. It provides constructs for modeling hardware systems at different levels of abstraction.

1. Key Concepts

1.1 Hardware Modeling

SystemC allows modeling of:

• Digital hardware systems
• Mixed hardware/software systems
• System-on-chip (SoC) designs
• Embedded systems

1.2 Simulation Kernel

SystemC provides a discrete-event simulation kernel that:

• Manages time advancement
• Schedules processes and events
• Handles signal updates and notifications

1.3 Design Hierarchy

SystemC supports hierarchical design through:

• Modules: Basic building blocks (SC_MODULE)
• Ports: Interface connections
• Channels: Communication between modules
• Processes: Concurrent execution units

2. Basic SystemC Constructs

2.1 Modules

SC_MODULE(MyModule) {
    // Ports
    sc_in<bool> clk;
    sc_in<int> data_in;
    sc_out<int> data_out;
    
    // Constructor
    SC_CTOR(MyModule) {
        SC_METHOD(process_data);
        sensitive << clk.pos();
    }
    
    void process_data() {
        data_out.write(data_in.read() * 2);
    }
};

2.2 Processes

• SC_METHOD: Combinational logic, runs to completion
• SC_THREAD: Sequential logic, can wait and suspend
• SC_CTHREAD: Clocked thread, synchronizes with clock edges

2.3 Signals and Channels

sc_signal<int> internal_sig;
sc_clock clk("clock", 10, SC_NS);
sc_fifo<int> data_fifo(16);

3. Simulation Flow

1. Elaboration: Build design hierarchy, connect ports
2. Initialization: Initialize signals and processes
3. Simulation: Execute processes, advance time, update signals
4. Cleanup: Free resources and finish simulation

4. Applications

SystemC is commonly used for:

• Electronic System Level (ESL) design
• Virtual prototyping of embedded systems
• Performance modeling and analysis
• Hardware/software co-design
• System verification and validation

SystemC bridges the gap between high-level system modeling and detailed hardware implementation, enabling early software development and system optimization.