Loop backward through array -- howto do it brachless

[Stefan_Salewski]

Assume we have an array with index 0 to 3, we want to print elements in a never 
ending loop. Start index is i. Looping forward is of course
    
    
    i = (i + 1) mod 4
    #print element[i]
    
    
    Run

I have no idea to do it branchless in backward order currently, this is wrong 
of course:
    
    
    i = (i - 1) mod 4
    #print element[i]
    
    
    Run

Should be easy I guess, but no idea currently :-(