Is there a mathematical method that takes a matrix and generates a "diamond" of values from rotating it 45 degrees?

I’m writing a program that simulates a game, and to do so I need to come up with a function that can rotate a matrix by 45 degrees, essentially. So if I have a 5 by 5 matrix, I need to generate a list of lists looking like:
5,5
4,1 5,2
3,1 4,2 5,3
etc etc all the way down to 1,5

I’m wondering how an operation like this would work…thanks!