我正在对IDA中的一个大型Amiga程序进行逆向工程，并且已经取得了很大的进步。但是，有些东西我还不太清楚。即，我发现了几个子例程，这些子例程使用了我认为是“跳转表”的子例程-但是我不太清楚它们是如何工作的。有人有建议吗？
moveq #0,d0
move.b d7,d0 ; set D0 to a byte from CTRL
subq.w #1,d0 ; subtract 1 from it
blt.w finish_29ABA ; if D0 is less than 1, branch
cmpi.w #$16,d0
bge.w finish_29ABA ; if D0 is greater than or equal to 16, branch
add.w d0,d0 ; otherwise, double D0
move.w dword_29918(pc,d0.w),d0
jmp dword_29918+2(pc,d0.w)
; ---------------------------------------------------------------------------
dword_29918: dc.l $400036 ; CODE XREF: serialCtrlCmd+E0j
dc.l $360036
dc.l $3601A0
dc.l $3601A0
dc.l $1A001A0
dc.l $360040
dc.l $2A01A0
dc.l $400036
dc.l $3601A0
dc.l $1A00036
dc.l $1A00036
dc.l $33FC0003
dc.l HEAP_3B897+$41A7 ; CTRLRead3
; ---------------------------------------------------------------------------
bra.w finish_29ABA
; ---------------------------------------------------------------------------
tst.w (CTRL_36494).l
bne.w return_29AF6
moveq #1,d0
lea ((HEAP_3B897+$2665)).l,a0
adda.w (CTRLRead1).l,a0
move.b d7,(a0)
moveq #0,d1
move.b d7,d1
move.w d1,(CTRLRead2).l
move.w (CTRLCmds).l,d1
addq.w #1,d1
move.w d1,(CTRLCmds).l ; Increment CTRL Cmds by 1
move.w d0,(CTRLRead3).l
bra.w finish_29ABA
最佳答案
blt.w finish_29ABA ; \
cmpi.w #$16,d0 ; > These insns check that the index is in range
bge.w finish_29ABA ; /
add.w d0,d0 ; since the jump table contains words,
; multiply the index by 2, to get a word index
move.w dword_29918(pc,d0.w),d0 ; get a word from the jump table, indexed by d0
jmp dword_29918+2(pc,d0.w) ; perform an indirect jump to (PC,d0)
dword_29918: ; the following are offsets encoded as words
; 0040 0036 0036 0036...
这通常是C
switch语句的结果。关于assembly - 协助68k组装-跳转表？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/6538342/