*        do i=8 to 1 by -2
         L      3,1                r3 index and start value 8
         LH     4,=H'-2'           r4 step -2
         L      5,8                r5 to value 1
LOOPI    EQU    *
         ...                       loop 4 times (r3=8,6,4,2)
         BXH    3,4,LOOPI          r3=r3+r4; if r3>r5 then loop