Question

I m learning subroutines in Arm assembly and I m confused with an example. For " bne Body " doesn t it need a cmp x, y before it? What s it comparing?

@ Sum of the first "MAX" Fibonacci with subroutine
.text
.global _start
.equ MAX,10
_start: mov r1,#MAX
bl Fib 
exit: swi 0x11 @ Terminate the program
@Subroutine to compute sum of n Fibonacci numbers
Fib: sub r1,r1,#2 @ Counter - 2
mov r2,#1
mov r3,#2
mov r0,#3
Body: add r4,r2,r3
add r0,r0,r4 @ Update Sum
mov r2,r3
mov r3,r4
Decr: subs r1,r1,#
bne Body @ If Count != 0, repeat loop
Done: mov pc,lr @ Return from subroutine

Answer 1

该次指示规定了旗帜,而布恩则在悬挂这些国旗。基本上,它比较了1至0,如果它不等于0。比较实际上是一种分站式操作,即你如何比较万国邮联中的2个数字。较老的国邮联甚至比较了密码,而许多这类编码实际上只是次要的同义词(如果存在的话,可能会在旗帜上出现小的差别,而且为了明确起见,你应当使用比较代码。

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