Verilog-REPL

Evaluate Verilog expressions interactively

How to run this

If you're using nix:

nix run github:mpardalos/verilog-repl

Otherwise:

wget https://raw.githubusercontent.com/mpardalos/verilog-repl/refs/heads/master/verilog-repl.py
chmod +x verilog-repl.py
./verilog-repl.py

You will need either iverilog or verilator available in your $PATH.

Usage

You can get help with help or ?

iverilog> ?

Documented commands (type help <topic>):
========================================
:EOF  :e  :env  :eval  :exit  :help  :q  :quit  :reg  :set  :unset

Type in a verilog expression and it gets evaluated

iverilog> 32'd5 + 2'b01
Decimal: |         6|
Hex:     |00000006|
Binary:  |00000000000000000000000000000110|

If you want to evaluate the expression at a specific width, you can specify that before the expression:

iverilog> [15:0] 1
Decimal: |    1|
Hex:     |0001|
Binary:  |0000000000000001|

You can also create registers (with a constant value) with reg

iverilog> reg [7:0] x = 8'd42;
Added reg [7:0] x = 8'd42 to environment
iverilog> reg [5:0] y = 8'd21;
Added reg [5:0] y = 8'd21 to environment
iverilog> x + y
Decimal: | 63|
Hex:     |3f|
Binary:  |00111111|

You can switch between iverilog and verilator:

iverilog> 1
Decimal: |          1|
Hex:     |00000001|
Binary:  |00000000000000000000000000000001|
iverilog> :set verilator
verilator> 1
Decimal: |          1|
Hex:     |00000001|
Binary:  |00000000000000000000000000000001|