4-bit_Register-Verilog

A verilog program that mimics the circuitry of a 4-bit register implemented with four 4x1 multiplexers and four D-Flipflops.
The register operates according to the value of the select lines as shown below:-

s1 s0 Output
0 0 No change
0 1 Complement Output
1 0 Shift bits to right
0 1 Shift bits to the left
'Load' input is used to enable the D-FlipFlop.
'Reset' used to remove don't care state and set the initial values of the flip flops to 0.

The lib.v file contains the code for the basic gates, D-flip flop and a 2x1 multiplexer. The source.v contains code for the 4-bit register and four 4x1 multiplexers. The reg_tb files contains the input test bench values used by the program as input.

Link to their website: Icarus-Verilog

Steps to run this code:-

Open command prompt in the location where the files are stored and type the following commands to run the code

iverilog -o reg_v lib.v source.v reg_tb.v  

vvp reg_v  

gtkwave tb_file.vcd 

(enter the dump file name specified in the reg_tb file for tb_file.vcd)