Question

我刚刚开始一个流水线编程课，我遇到了问题的问题，我加了240到49，我知道它会溢出，我的目标是让注册当这些数字溢出时，1等于1。我知道当我添加进位标志时会设置进位标志，但我不确定如何使用此标志使r1等于1.

 This program should calculate:
; R0 = R16 + R17 + R18
;
;--*1 Do not change anything between here and the line starting with *--
.cseg
    ldi r16, 0x30
    ldi r17, 0x31
    ldi r18, 0x32
;*--1 Do not change anything above this line to the --*

;***
; Your code goes here:
;
    add r0, r16
    add r0, r17
    add r0, r18


;****

;--*2 Do not change anything between here and the line starting with *--
done:   jmp done
;*--2 Do not change anything above this line to the --*

Answer 1

我确信有更聪明的方法，但你可以使用brcs，如果携带设置分支：

add r0, r16
add r0, r17
add r0, r18
brcs carry ; Branch if carry set

carry: ldi r1, 0x1 ; Branch destination

AVR Studio - AVR模拟器2携带旗帜问题

1 个答案: