Question

我对手臂组装非常新，我正在使用武器进行学校项目。我有很多问题。

我需要从txtfile读取多行，每行都有一个字符串，最多需要85个字节（每行）。我的程序只读取第一行，我不知道如何读取文件的其余部分。
我必须从每一行中取出每个字符，如果字符值我称之为“a”（（a> = 65＆amp;＆amp; a＆lt; = 77）||（a＆gt; = 97＆amp; ＆amp; a＆lt; = 109））。如果（（a> = 78＆amp;＆amp; a＆lt; = 109）||（a> = 110＆amp;＆amp; a＆lt; = 122）），我必须减去13。如果（a == 32）那么我打印出空格并移动到下一个字符。我不明白如何使用分支机构这样做...

循环逐个字符处理并将字符输出到stdout中。到目前为止，这是我的代码...我花了几天时间这个小时，我无法绕过这个。到目前为止我只接触过java。

.equ SWI_Open, 0x66 @open a file
.equ SWI_Close,0x68 @close a file
.equ SWI_PrChr,0x00 @ Write an ASCII char to Stdout
.equ SWI_PrStr, 0x69 @ Write a null-ending string
.equ SWI_PrInt,0x6b @ Write an Integer
.equ SWI_RdInt,0x6c @ Read an Integer from a file
.equ SWI_RdStr, 0x6a @ Read string from file
.equ Stdout, 1 @ Set output target to be Stdout
.equ SWI_Exit, 0x11 @ Stop execution
.global _start
.text
_start:

ldr r0,=InFileName @ set Name for input file
mov r1,#0 @ mode is input
swi SWI_Open @ open file for input
ldr r1,=InFileHandle
str r0,[r1]
ldr r7,[r1]
ldr r1,=array
mov r2,#85
swi SWI_RdStr @stores the string into =array 

mov r5,#0 @r5 is index

loop: @processes a single char then loops back
cmp r5,r2 @r2 is 83
bge procstop
ldrb r4,[r1,r5] @loads the character value from =array[r5] into r4

cmp r4,#77
ble add
cmp r4,#65
bge add

cmp r4,#97
bge add
cmp r4,#109 
ble add

cmp r4,#78
bge sub
cmp r4,#90
ble sub

cmp r4,#110
bge sub
cmp r4,#122
ble sub

add:
add r4,r4,#13

sub:
sub r4,r4,#13

mov r0,r4
swi SWI_PrChr

strb r4,[r1,r5]
add r5,r5,#1
B loop
procstop:

mov r0,#Stdout
swi SWI_PrStr
swi SWI_Exit

.data
InFileName: .asciz "lab4.txt"
EndOfFileMsg: .asciz "End of file reached\n"
ColonSpace: .asciz": "
NL: .asciz "\n " @ new line
array: .skip 85
.align
InFileHandle: .word 0


.end

Answer 1

啊我明白了。我不知道为什么我不早点想到这个。不需要比较所有这些，只需要每次比较一个，从最小的比较到最大的比较，基本上是一个if / else if语句链

臂组件凯撒密码加密

1 个答案: