SystemC -- A notion of time

1、simulation kernel用sc_time数据类型来跟踪仿真时间，指定delay和timeouts。

sc_time是用一个64bit的无符号整型数来表示。

SC_SECseconds 10^0 秒

SC_MSmilliseconds 10^-3 毫秒

SC_USmicroseconds 10^-6 微秒

SC_NSnanoseconds 10^-9 纳秒

SC_PSpicoseconds 10^-12 皮秒

SC_FSfemtoseconds 10^-15 飞秒

sc_time_stamp()用来获取当前的仿真时间，返回值是一个sc_time对象。

sc_simulation_time()returns time as a double in the currentdefault time unit.

Info: (I804) /IEEE_Std_1666/deprecated: sc_simulation_time() is deprecated use sc_time_stamp()

To establish the default time unit, call sc_set_default_time_unit(). you must call this routine prior to call time specifications and prior to

the initiation of sc_start().

sc_start()启动仿真，括号中可带参数，指定的时间流逝后，仿真停止。

If you provide a time argument, simulation stops after the specified simulation time has elapsed.

#include "stdafx.h" #include <systemc.h> #include <iostream> using namespace std; SC_MODULE(My_Module) { SC_CTOR(My_Module) { SC_THREAD(mytime); } void mytime(); }; void My_Module::mytime() { int a = 5,b=3,c; c = a + b; wait(5,SC_NS); cout<<"The time is now "<<sc_time_stamp()<<"!"<<endl; sc_time t_delay(2,SC_MS); t_delay *= 2; cout<<"Delaying "<<t_delay<<endl; wait(t_delay); cout<<"The time is now "<<sc_time_stamp()<<"!"<<endl; } int sc_main(int sc_argc,char * argv[]) { My_Module md(""); sc_time m_time(5,SC_SEC); //sc_start(); //sc_start(10.0,SC_MS); //limit sim to 10 ms sc_start(m_time);//start sim and maximum simulation time system("pause"); return 0; }

输出：

#include "stdafx.h" #include <systemc.h> #include <iostream> using namespace std; int sc_main(int sc_argc,char * argv[]) { sc_set_time_resolution(1.0,SC_MS); sc_start(7200,SC_SEC);//limit simulation to 2 hours(or 7200 secs) sc_time st = sc_time_stamp();//获取当前仿真时刻和时间单位 double t = sc_simulation_time();//仅仅获取当前仿真时刻而无时间单位 //sc_cycle、sc_initialize：用于完成周期级仿真。 unsigned hours = int(t/3600.0); t -= 3600*hours; unsigned minutes = int(t/60.0); t -= 60.0*minutes; double seconds = t; cout<< hours << " hours " << minutes << " minutes " << seconds << " seconds " << endl; //system("pause"); return 0; }

输出：

上面时间输出错误，没有考虑到time units。

sc_report_handler::set_actions("/IEEE_Std_1666/deprecated", SC_DO_NOTHING); 加入该句可以关闭有关deprecated 的warnings。

#include <systemc.h> #include <iostream> #include <math.h> using namespace std; int sc_main(int sc_argc,char * argv[]) { sc_report_handler::set_actions("/IEEE_Std_1666/deprecated", SC_DO_NOTHING); cout<<"=== my time resolution is "<<sc_get_time_resolution()<<endl;//ps 10^-12s double t1 = sc_get_time_resolution().to_seconds(); cout<<"=== my time resolution is "<<t1<<"s."<<endl; sc_start(7296,SC_SEC); sc_time t = sc_time_stamp(); cout<<"Current time is "<<t<<endl; double t2 = sc_simulation_time();//ns? long long index = pow((double)10,(double)9); double ts = t2/index; // ns --> s unsigned hours = (int)(ts/3600.0); ts -= 3600 * hours; unsigned minutes = (int)(ts/60.0); ts -= 60 * minutes; double seconds = ts; cout <<"Time is "<< hours <<" hours " << minutes << " minutes " << seconds << " seconds " << endl; system("pause"); return 0; }

输出：

#include <systemc.h> #include <iostream> using namespace std; int sc_main(int sc_argc,char * argv[]) { sc_report_handler::set_actions("/IEEE_Std_1666/deprecated", SC_DO_NOTHING); /* for example,if the specified time resolution is 100ps, then coding 20ps will result in an effective value of 0 ps */ sc_set_time_resolution(1,SC_NS); sc_set_default_time_unit(1,SC_MS); //establish the default time unit cout<<"=== my time resolution is "<<sc_get_time_resolution()<<endl;//ns 10^-9s double t1 = sc_get_time_resolution().to_seconds(); cout<<"=== my time resolution is "<<t1<<"s."<<endl; sc_start(7296,SC_SEC); sc_time t = sc_time_stamp(); cout<<"Current time is "<<t<<endl; double t2 = sc_simulation_time();//default time unit double ts = t2/1000; // ms --> s unsigned hours = (int)(ts/3600.0); ts -= 3600 * hours; unsigned minutes = (int)(ts/60.0); ts -= 60 * minutes; double seconds = ts; cout <<"Time is "<< hours <<" hours " << minutes << " minutes " << seconds << " seconds " << endl; system("pause"); return 0; }

输出：