Shaved another 2 bytes off wchrmas pattern, code size is down to 56 bytes! :)

Two subroutine calls and the return statement can be replaced with inlined code and a loop, using a negation as loop counter:

        bsr.b   .mod    
        bsr.b   .mod    

.mod    ; do counter updates
        rts             
        neg.l   d0      
        blt.b   .mod