Why can't a SystemC trace capture the last signal?

Question

Here is my program:

#include <systemc.h> int sc_main(int argc, char* argv[]) { sc_signal<sc_logic> a, b, c, d; // trace file creation sc_trace_file *tf = sc_create_vcd_trace_file("test"); //tf->set_time_unit(1, SC_PS); sc_trace(tf, a, "A"); sc_trace(tf, b, "B"); sc_trace(tf, c, "C"); sc_trace(tf, d, "D"); sc_start(0, SC_PS); bool a_tmp = false; bool b_tmp = true; int c_tmp = 0; int d_tmp = 1; a = sc_logic(a_tmp); b = sc_logic(b_tmp); c = sc_logic(c_tmp); d = static_cast<sc_logic>(d_tmp); sc_start(1, SC_PS); a = SC_LOGIC_1; b = SC_LOGIC_1; c = SC_LOGIC_0; d = SC_LOGIC_1; sc_start(1, SC_PS); a = SC_LOGIC_0; b = SC_LOGIC_0; c = SC_LOGIC_1; d = SC_LOGIC_0; sc_start(1, SC_PS); a = SC_LOGIC_1; b = SC_LOGIC_0; c = SC_LOGIC_1; d = SC_LOGIC_0; sc_start(1, SC_PS); sc_close_vcd_trace_file(tf); return 0; } 

It is very strange that the waveform between 3 ~ 4ps was lost and was not captured by the VCD file. What is the reason? Even changing a, b, c, d to variables cannot solve this problem.

Answer 1

I just tried my code, and this is the trace file I received ( test.vcd ):

 $date Sep 07, 2015 20:30:28 $end $version SystemC 2.3.1-Accellera --- Nov 29 2014 15:29:06 $end $timescale 1 ps $end $scope module SystemC $end $var wire 1 aaaaa A $end $var wire 1 aaaab B $end $var wire 1 aaaac C $end $var wire 1 aaaad D $end $upscope $end $enddefinitions $end $comment All initial values are dumped below at time 0 sec = 0 timescale units. $end $dumpvars xaaaaa xaaaab xaaaac xaaaad $end #0 0aaaaa 1aaaab 0aaaac 1aaaad #1 1aaaaa #2 0aaaaa 0aaaab 1aaaac 0aaaad #3 1aaaaa 

Which looks right to me. The table below shows the same data:

  abcd at 0 ps (0) (1) (0) (1) at 1 ps (1) 1 0 1 at 2 ps (0) (0) (1) (0) at 3 ps (1) 0 1 0 at 4 ps No more stimulus, simulation ends () denotes a changed value