Command-line verification

Subsections:
Substituting libraries
Other verification options
Testing multiple files
Test Vectors

Logisim includes basic support for executing circuits from the command-line. This is intended both to help with scripted verification of circuit designs and to help instructors perform automated testing of students' solutions.

We'll start by seeing how to execute a circuit from the command line. For our example, we'll suppose we've built the below circuit in a file named adder-test.circ. It uses a two-bit adder as a subcircuit and iterates using a counter through all 16 possible inputs to it.

After this circuit has been built, we then execute Logisim from the command line, providing the filename of the project and the -tty option with the < table parameter.

java -jar logisim-filename.jar adder-test.circ -tty table

Without bringing up any windows, Logisim loads the circuit and begins to execute it, ticking any clocks as fast as it can while completing the propagation between each tick. After each propagation is completed, Logisim loads the current values of the output pins; if any have changed from the previous propagation, then all values are displayed in tab-delimited format. If there is an output pin labeled with the special word halt (case sensitive), its output is not displayed — but once the pin's value reaches 1 after a propagation is completed, Logisim ends the simulation.

For our example, Logisim displays the table below. Because we have two output pins corresponding to the two inputs a and b into the two-bit adder, these outputs are included as the first two columns of the output. And there is another output pin sum corresponding to the two-bit adder's output, so it is the third column. The columns are ordered left-to-right according to the top-down ordering within the circuit.

Copy

00 00 000
01 00 001
10 00 010
11 00 011
00 01 001
01 01 010
10 01 011
11 01 100
00 10 010
01 10 011
10 10 100
11 10 101
00 11 011
01 11 100
10 11 101
11 11 110

Next: Substituting libraries.