mov  r4,#6
   call setb_ind
   ...
setb_ind:
   xch  a,r4
   push acc
   add  a,#setb_ind_T-setb_ind_X
   movc a,@a+pc
setb_ind_X:
   orl  a,r4
   mov  r4,a
   pop  acc
   xch  a,r4
   ret

setb_ind_T:  
   db   1,2,4,8,16,32,64,128