Working example of digital signature algorithm

Does anyone have an example DSA with simple values ​​on how to compute r, s and check v == r. Since this standard has been around for a while and is implemented in libraries like Java Cryptography Extension I find it very difficult to find an example of how the algorithm works.

Compute r=(gk mod p) mod q 
Compute s=(k-1 * (x * r + i)) mod q 
Verifying a signature; again i is the input, and (r,s) is the signature. 

u1 = (s-1 * i) mod q 
u2 = (s-1 * r) mod q 
v = ((gu1 * yu2) mod p) mod q 
If v equals r, the signature is valid.

      

        
        
        
      

    

Thanks,