Learning SystemC

1. Learning SystemC Freeha Azmat Saba Zia Dec 02, 2008

2. Agenda • Installation • Introduction • From Verilog to SystemC • Counter as an Example • Complete SystemC Modeling

3. Installation on Linux • Download System2.2 from www.systemc.org • Run following commands in terminal • cd systemC-2.2 • mkdirobjdir • cdobjdir • setenv CXX g++ • ./configure • Gmake debug • Gmakeinstaal • Gmake check • Download dinotrace from www.veripool.com/dinotrace • tar xvfdinotrace*.tg*z • cddinotrace* • ./configure • make • # Test ./dinotrace traces/ascii.tra • make install

4. Introduction : System C : • Is a C++ Library for system Level Modeling • Supports various abstraction Layers System C is used for : • Fast and efficient designs • System verification

5. SystemC VS C++ C ++ System C • Sequential Language • Not suitable for complex and detailed systems • Data Types are not suitable for Hardware Implementation • Parallel Processing is possible • Incorporate delays, Clocks or Time • Data Types dedicated to Hardware modeling e.g bit, vector types as well as fixed point types.

6. SystemC implementation • Modules • Processes • Ports and Interfaces • Channels

7. Modules : • Is a C++ Class • Encapsulates hardware /software description • Any Modules has to be derived from the existing class sc_module. • SystemC modules are analogous to verilog modules or VHDL entity / architecture pair. • Modules communicate to other modules via ports.

8. Ports and Interfaces : • Ports are defined as objects inside a module • Publically available to the outside world through the use of public Keyword. • Predefined Ports: sc_in<>,sc_out<>,sc_inout<>,sc_fifo_in<>,sc_fifo_out<> Example :sc_in<bool>clk; • User Defined Ports are defined with the help of sc_port class Example:Sc_port <sc_signal_in_if<bool>, 1> clk;

9. Processes : • Two kinds of Processes : SC_METHOD: • cannot be suspended during its execution • Once the execution of SC_METHOD as been performed it halts and waits for new activities on its sensitivity list Similar to Verilogalways block SC_THREAD : • Can be suspended during execution and resumed at a later stage • SC_THREAD only executes once during simulation and then suspends Similar to Verilog initial Block

10. Channels : • SystemC ‘s communication Medium. • Modules communicate via ports and channels • They are similar to Verilogwire and VHDL signal • System C provides a exhaustive range of pre-defined channels for generic uses such as sc_signal. • This Feature of language differentiate it from VHDL and Verilog

11. From Verilog to SystemC module name(); // module functionality endmodule SC_MODULE(name) { //module functionality } input A,B; output F; reg [3:0] G; sc_in<bool> A,B; sc_out<bool> F; sc_uint<4> G; always @(posedgeclk) begin //process sensitive //to rising edge of clock //input end SC_CTOR(name) { //process to execute SC_METHOD(myfunc); //sensitive to clock sensitive<<clk.pos(); }

12. From Verilog to SystemC add inst ( .F(F), .A(A), .B(B) ); add inst; SC_CTOR(name):inst(“INST”) { inst.A(A); inst.B(B); inst.F(F); } always @ () begin end SC_METHOD(myfunc); Initial begin end SC_THREAD (myfunc);

13. Counter #include <systemc.h> SC_MODULE(counter){ sc_in_clkclk; sc_in<bool>reset; sc_out<sc_uint<4> > counter_out; sc_uint<4> count; SC_CTOR(counter) { SC_METHOD(myfunc); sensitive<<clk.pos(); sensitive<<reset; } void myfunc() { count=0; if(reset.read()==1) counter_out.write(count); else count =count + 1; counter_out.write(count); cout<<counter_out.read()<<endl; } }; intsc_main(intargc,char *argv[]){ counter c("hello"); c.myfunc(); sc_start(); return(0); } module counter(clk,reset,counter_out); input clk; input reset; output [3:0]counter_out; reg [3:0]counter_out; always @(posedgeclk or negedge reset) begin if(!reset) counter_out<=0; else counter_out<=counter_out + 1; end endmodule

14. Complete SystemC Model REF:Introduction to SystemC by DeianTabakov Rice University Houston, TX

15. Stimulus Generator /************************stimulus.h *********************/ #include "systemc.h" SC_MODULE(stim) { sc_out<bool> A, B; sc_in<bool> Clk; void StimGen() { A.write(false); B.write(false); wait(); // wait for the next clock tick A.write(false); B.write(true); wait(); // wait for the next clock tick ... sc_stop(); // notify kernel to stop simulation } SC_CTOR(stim) { SC_THREAD(StimGen); sensitive << Clk.pos(); } }; REF:Introduction to SystemC by DeianTabakov Rice University Houston, TX

16. Monitor /************************monitor.h *********************/ #include "systemc.h" SC_MODULE(mon) { sc_in<bool> A, B, F; sc_in_clk Clk; void Monitor() { while(1) { wait(); cout << sc_time_stamp() << "\t " << A.read() << " " << B.read() << " " << F.read() << endl; } } SC_CTOR(mon) { SC_THREAD(Monitor); sensitive << Clk.pos(); cout << "Time\t A B F" << endl; } }; REF:Introduction to SystemC by DeianTabakov Rice University Houston, TX

17. Complete XOR Model #include "stim.h" #include "exor.h" #include "mon.h“ int sc_main(int argc, char* argv[]) { sc_signal<bool> ASig, BSig, FSig; sc_clock TestClk("TestClock", 10, SC_NS, 0.5); stim Stim1("Stimulus"); mon Monitor1("Monitor"); Stim1.A(ASig); Monitor1.A(ASig); Stim1.B(BSig); Monitor1.B(BSig); Stim1.Clk(TestClk); Monitor1.F(FSig); Monitor1.Clk(TestClk); exor DUV("exor"); DUV.A(ASig); DUV.B(BSig); DUV.F(FSig); sc_start(); // run forever return 0; } REF:Introduction to SystemC by DeianTabakov Rice University Houston, TX

18. Simulation in Terminal REF:Introduction to SystemC by DeianTabakov Rice University Houston, TX