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_SEC seconds 10^0 秒

SC_MS milliseconds 10^-3 毫秒

SC_US microseconds 10^-6 微秒

SC_NS nanoseconds 10^-9 纳秒

SC_PS picoseconds 10^-12 皮秒

SC_FS femtoseconds 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 current default 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：