Propositional Circuit Configuration Format

This is a small side-project I worked on during my first year at Imperial College London. I started this for two reasons:

1. We had used a similar propositional circuit simulator in our first year Computer Systems module and I felt that it was quite clunky
2. I had just started learning C and wanted practice with dynamic allocation of some more complicated structures

Inputs

Inputs may either be given a defined value, or just marked as existing. (The GIVEN and ALL modes respectively). Given inputs are specified in the form I-label [1|0] (POSIX regex is (^IN-[[:alnum:]]+ [1|0]$)) For example, IN-a 1 is an input, of value 1, and IN-b 0 is an input, of value 0. Otherwise, inputs are specified in the form I-label (POSIX regex is (^IN-[[:alnum:]]+$))

If the ALL mode is to be used, the -a flag should be used from the command line. The filepath to the config file should always be last.

Gates

The available gates to use are:

• AND
• OR
• NOT
• XOR
• NOR
• NAND

Gates are specified in the form type# input1 input2 (POSIX regex to match the gate type is (^(AND|OR|NOT|XOR|NOR|NAND)[0-9]+))

For example, AND1 I1 I2 is the first AND gate, taking inputs from the first and second inputs to the circuit. OR1 AND1 I3 is the first OR gate, taking inputs from the first AND gate and third input. NOT gates only have one input, so can be written as NOT# input1.

Outputs

Logic gates defined earlier in the configuration file can be marked as circuit outputs.

Outputs are specified in the form O-label gate (POSIX regex for the initial output part is (^OUT-[[:alnum:]]+). Note that an input label may be used as the gate for an output if desired).

For example, OUT-res OR1 marks the first OR gate as the res output of the circuit.

Layout

All circuit inputs should be defined first. Then all logic gates should be defined, in such a way that a logic gate is only defined where both of its inputs are previously defined. Finally, all circuit outputs should be defined. Configurations should be written in a .txt file, where the relative path to the file will be passed as a command-line argument to the program.

Examples

The examples sub-directory is aptly named. So far it contains:

• A 2-input multiplexer with defined inputs
• A 2-input multiplexer with undefined inputs
• A 1-input decoder with defined inputs
• A 1-input decoder with undefined inputs
• A half-adder with undefined inputs