DBRA - M68K instruction reference

dbraDecrement and branch 
Decrements the first operand by 1 and branches to the specified address if the first operand is not -1.
Size .w
XNZVC –––––
Changes no flag
Forms  dbra ,   
Operands Dn A data register, d0 to d7. More
label A branch target, written as a label or address. The assembler calculates the relative displacement. More
dbra is the same as dbf (will decrement until it reaches -1)
 * --- Loops d0+1 times (counter goes 5,4,3,2,1,0,-1 then stops) ---
move.l #5, d0
move.l #0, d1
loop:
    addq.l #1, d1
    dbra d0, loop
; d1 = 6 (looped 6 times)