Euclid's algorithm

Euclid's algorithm is used to determine the Greatest Common Divisor of two values. Despite it's simplicity, the only previous redcode implementation I can find is broken.

Implementation in Redcode:

          org    euclid+2

euclid    mod.ab #a,                #b
          mov.x  euclid,            euclid
          jmn.a  euclid,            euclid