Trung tâm đào tạo thiết kế vi mạch Semicon


  • ĐĂNG KÝ TÀI KHOẢN ĐỂ TRUY CẬP NHIỀU TÀI LIỆU HƠN!
  • Đăng ký
    *
    *
    *
    *
    *
    Fields marked with an asterisk (*) are required.
semi4_volunteering.jpg

Process In SystemC Part IV

Email In PDF.

dont_initialize()
Process and threads (not the cthreads) get executed automatically in Constrcutor even if event in sensitivity list does not occur. To prevent this unintensional execution, use dont_initialize() function as shown in example.

Example : dont_initialize()
  1 #include "systemc.h"
  2 
  3 SC_MODULE (tff_sync_reset) {
  4   sc_in    <bool> data, clk, reset  ;
  5   sc_out   <bool> q;
  6 
  7   bool q_l ;
  8 
  9   void tff () {
 10     if (reset.read()) {
 11       q_l = 0;
 12     } else if (data.read()) {
 13       q_l =  ! q_l;
 14     }
 15     q.write(q_l);
 16   }
 17 
 18   SC_CTOR(tff_sync_reset) {
 19     SC_METHOD (tff);
 20       dont_initialize();
 21       sensitive << clk.pos();
 22   }
 23 
 24 };
 25 
 26 SC_MODULE (tff_tb) {
 27   sc_in<bool> clk;
 28  
 29   sc_signal <bool> data, reset  ;
 30   sc_signal   <bool> q;
 31   tff_sync_reset *dut;
 32 
 33   void do_test() {
 34     cout << "@" << sc_time_stamp() <<" Starting test"<<endl;
 35     wait();
 36     cout << "@" << sc_time_stamp() <<" Asserting reset"<<endl;
 37     reset = true; 
 38     wait(4);
 39     cout << "@" << sc_time_stamp() <<" De-Asserting reset"<<endl;
 40     reset = false; 
 41     wait(3);
 42     cout << "@" << sc_time_stamp() <<" Asserting Data input"<<endl;
 43     data = true; 
 44     wait(3);
 45     data = false; 
 46     cout << "@" << sc_time_stamp() <<" De-Asserting Data input"<<endl;
 47     wait(3);
 48     cout << "@" << sc_time_stamp() <<" Terminating simulation"<<endl;
 49     sc_stop();
 50   }
 51 
 52   SC_CTOR(tff_tb) {
 53     dut = new tff_sync_reset ("TFF");
 54     dut->clk    (clk);
 55     dut->reset  (reset);
 56     dut->data   (data);
 57     dut->q      (q);
 58     SC_THREAD (do_test);
 59       dont_initialize();
 60       sensitive << clk.pos();
 61   }
 62 };
 63 
 64 int sc_main (int argc, char* argv[]) {
 65   sc_clock clock ("my_clock",1,0.5);
 66 
 67   tff_tb  object("TFF_TB");
 68     object.clk (clock.signal());
 69   sc_trace_file *wf = sc_create_vcd_trace_file("tff");
 70     sc_trace(wf, object.clk, "clk");
 71     sc_trace(wf, object.reset, "reset");
 72     sc_trace(wf, object.data, "data");
 73     sc_trace(wf, object.q, "q");
 74 
 75   sc_start(0);
 76   sc_start();
 77   sc_close_vcd_trace_file(wf);
 78   return 0;// Terminate simulation
79 }
Simulation Output : dont_initialize()
 @0 s Starting test

 WARNING: Default time step is used for VCD tracing.

 @1 ns Asserting reset

 @5 ns De-Asserting reset

 @8 ns Asserting Data input

 @11 ns De-Asserting Data input

 @14 ns Terminating simulation

 SystemC: simulation stopped by user.

Wait Until
In an SC_CTHREAD process wait_until() methods can be used to control the execution of the process. The wait_until() method will halt the execution of the process until a specific event has occurred. This specific event is specified by the expression to the wait_until() method.
This statement will halt execution of the process until the new value of "expr" is true. The delayed() method is required to get the correct value of the object. A compilation error will result if the delayed() method is not present. Only a boolean expression is allowed as argument of the wait_until() function and only boolean signal objects can be used in the boolean expressions. Boolean signal objects include clock type sc_clock, signal type sc_signal, and port types sc_in, sc_out, and sc_inout

Example : Wait Until

  1 //-----------------------------------------------------

  2 // This is my second Systemc Example

  3 // Design Name : first_counter

  4 // File Name : first_counter.cpp

  5 // Function : This is a 4 bit up-counter with

  6 // Synchronous active high reset and

  7 // with active high enable signal

  8 //-----------------------------------------------------

  9 #include "systemc.h"

 10

 11 SC_MODULE (first_counter) {

 12   sc_in_clk     clock ;      // Clock input of the design

 13   sc_in<bool>   reset ;      // active high, synchronous Reset input

 14   sc_in<bool>   enable;      // Active high enable signal for counter

 15   sc_out<sc_uint<4> > counter_out; // 4 bit vector output of the counter

 16

 17   //------------Local Variables Here---------------------

 18   sc_uint<4> count;

 19

 20   //------------Code Starts Here-------------------------

 21   // Below function implements actual counter logic

 22   void incr_count () {

 23     // For threads, we need to have while true loop

 24     while (true) {

 25       // Wait until rest is true or enable is true

 26       // Every wait_until delays execution by one clock.pos()

 27       wait_until(reset.delayed() == true || enable.delayed() == true);

 28       if (reset.read() == 1) {

 29         count =  0;

 30         counter_out.write(count);

 31       // If enable is active, then we increment the counter

 32       } else if (enable.read() == 1) {

 33         count = count + 1;

 34         counter_out.write(count);

 35       }

 36     }

 37   } // End of function incr_count

 38

 39   // Below functions prints value of count when ever it changes

 40   void print_count () {

 41     while (true) {

 42       wait();

 43       cout<<"@" << sc_time_stamp() <<

 44         " :: Counter Value "<endl;

 45     }

 46   }

 47

 48   // Constructor for the counter

 49   // Since this counter is a positive edge trigged one,

 50   // We trigger the below block with respect to positive

 51   // edge of the clock

 52   SC_CTOR(first_counter) {

 53     // Edge sensitive to clock

 54     SC_CTHREAD(incr_count, clock.pos());

 55     // Level Sensitive to change in counter output

 56     SC_THREAD(print_count);

 57     sensitive << counter_out;

 58   } // End of Constructor

 59

 60 }; // End of Module counter

 Bạn Có Đam Mê Với Vi Mạch hay Nhúng      -     Bạn Muốn Trau Dồi Thêm Kĩ Năng

Mong Muốn Có Thêm Cơ Hội Trong Công Việc

Và Trở Thành Một Người Có Giá Trị Hơn

Bạn Chưa Biết Phương Thức Nào Nhanh Chóng Để Đạt Được Chúng

Hãy Để Chúng Tôi Hỗ Trợ Cho Bạn. SEMICON  

 

 

CÁC BÀI VIẾT LIÊN QUAN