The aim of this example it build and simulate a circuit which is equivalent to an XOR gate for two inputs. We have to build this using only continuous assignments. Let
a and
b be inputs to our circuit. Let
s be the output. Then, the program to to generate
s as an XOR function of
a and
b is as follows.
#include <lcs/bus.h> #include <lcs/tester.h> #include <lcs/simul.h> #include <lcs/changeMonitor.h> using namespace lcs; int main(void) { Bus<1> s, a, b; // Continuous assignment statements to generate // the XOR output. The template parameter // indicates the assignment delay. We have used // 0 delay here. s.cass<0>(a^b); ChangeMonitor<2> input((a,b), "Input", DUMP_ON); ChangeMonitor<1> output(s, "Output", DUMP_ON); Tester<2> tester((a,b)); Simulation::setStopTime(500); Simulation::start(); }
The output when the above program is compiled and run is as below. See this for information on interpreting the output.
At time: 0, Input: 00 At time: 0, Output: 0 At time: 200, Input: 01 At time: 200, Output: 1 At time: 300, Input: 10 At time: 400, Input: 11 At time: 400, Output: 0
Below is the screenshot of the gtkwave plot of the generated VCD file.