在汇编komodo中循环减法10次

Question

在汇编komodo中循环减法10次。我想循环至少4次，但我可以设法循环无限次。如何循环x次。

        B main

    bottles     DEFW    4
    text        DEFB    " bottles sitting on a wall",0

        ALIGN

    main    

        LDR R0,text
        SWI 3

        LDR R0,bottles

loop    SUB R0,R0,#1
        SWI 4
        B loop
        SWI 2

Answer 1

Just for safety, move 'SUB R0,R0,#1' after the 'SWI 4', and instead of 'B loop' (unconditional branch) use 'BNE loop' (branch if not equal/zero). Oh, and change 'SUB' to 'SUBS' (= SUB + sets the fags).