You can create them with a case statement or a for loop.
The case statement versions are easy to understand, but they're specific to a particular decoder width.
The for-loop version can be made generic.
People on this forum will not usually give you code as part of their answer, since we assume you have been asked to do this as homework. However, we will provide feedback on your code if its clear you have taken the time to try it yourself.
Cheers,
Dave
