1. Easy way to debug with VCS
Jorge Ramírez
Synopsys Corp Application Engineer

2. Test program DUT Test program Simulation output DUT
module test; // Interface element to communicate with the DUT logic a, b; wire c1, c2; // DUT Instantiation DUT U1 (.in1(a), .in2(b), .out1(c1), .out2(c2)); // Test program initial begin a <= 0; b <= 0; #1 a <= 0; b <= 1; #1 $finish; End // Print on screen the execution initial Begin $display ("Simulation results:"); $display ( "A | B | C1| C2|"); $display ( "=========================="); $monitor ("%d | %d | %d | %d | ", a, b, c1, c2 ); end endmodule
module DUT (in1, in2, out1, out2); input in1, in2; output out1, out2; assign out1 = in1 & in2; assign out2 = in1 | in2; endmodule
DUT
DUT
Test program
Simulation output
Harness test program

3. VCS compilation
Compile all files with the following command (using vcs):
vcs –sverilog test.sv dut.v
Run the simulation by executing the binary created by VCS
./simv

4. Check the results
>./simv Chronologic VCS simulator copyright Contains Synopsys proprietary information. Compiler version A ; Runtime version A ; Jan 2 14: Simulation results: A | B | C1| C2| ========================== 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | $finish called from file "test.sv", line 27. $finish at simulation time 3 V C S S i m u l a t i o n R e p o r t Time: 3 CPU Time: seconds; Data structure size: 0.0Mb Fri Jan 2 14:21:

5. System task functions $display $monitor Display one message
$display (“port A= %b”, port_a)
$monitor
Display a message each time a varaible or an expression in the argument list chage
$monitor(“port A= %b”, port_a)

6. Escape sequence Argument Description %h or %H
Display in hexadecimal format
%d or %D
Display in decimal format
%o or %O
Display in octal format
%b or %B
Display in binary format
%c or %C
Display in ASCII character format
%l or %L
Display library binding information
%v or %V
Display net signal strength
%m or %M
Display hierarchical name
%s or %S
Display as a string
%t or %T
Display in current time format
%u or %U
Unformatted 2 value data
%z or %Z
Unformatted 4 value data
Argument
Description \n
The newline character \t
The tab character \\
The \ character
\"
The " character