反向时出现故障并在组装中显示字符串 [英] Trouble when reverse and display string in assembly

问题描述

这是我的代码:

model small
stack 100h

.data
string1 db "Khoa$"
string2 db 4 dup(?)
count dw 4
.code
begin:  
mov ax,@data
mov ds,ax
mov es,ax
mov cx,count
mov si,0
mov di,0
add di,count
dec di

again:  mov al,string1[si]
mov string2[di],al
inc si
dec di
loop again

mov ah,9
lea dx,string1
int 21h

end begin

在这部分

mov ah,9
lea dx,string1
int 21h

当我尝试显示string1进行控制台时，没关系. 但是string2没有结果.

when i try to display string1 to console, it's ok. but no result with string2.

我是组装的新手.请帮忙！

i'm new to assembly. Please help!

推荐答案

尽管这是家庭作业，但这是解决问题的合理尝试.我不知道您使用的是什么汇编程序-看起来像 MASM ，但我不确定这两行如何进行汇编而不会出现语法错误:

Although this is homework, this is a reasonable attempt at a solution. I don't know what assembler you are using - it looks like MASM but I'm unsure how these 2 lines could assemble without a syntax error:

model small
stack 100h

我认为这应该是(请注意前面的期间，因为它们是汇编器指令):

I think this should be (note the periods in front as they are assembler directives):

.model small
.stack 100h

string1最初为5个字符长，包括$以终止字符串.使用 int 21h/ah 9 时，字符串必须用$终止，否则它将继续在字符串末尾打印垃圾.考虑到这一点，您的输出缓冲区应该足够长以容纳5个字符，包括$ 所以string2应该定义为:

string1 is initially 5 characters long including the $ to terminate the string. When using int 21h/ah 9 strings need to be terminated with $ or it will continue to print junk beyond the end of your string. With that in mind your output buffer should be long enough to hold 5 characters including the $ so string2 should be defined as:

string2 db 5 dup(?)

代码中的主要问题是用$终止字符串.一种方法是在最初设置si和di寄存器时将$放置在数组的最后一个位置:

The primary problem in your code is terminating the string with a $. One way would be to place the $ in the last position of the array when you set up the si and di registers initially:

mov si,0
mov di,0
add di,count
mov string2[di],'$'   ; Put string terminator in last position
dec di

还请注意:

mov di,0
add di,count

可以简单地写为:

mov di, count

如果您正在使用 MASM ，要正常退出您的16位程序，您可能希望在end语句之前放置一个.exit指令:

If you are using MASM, to gracefully exit your 16 bit program you might want to put a .exit directive just before your end statement:

.exit
end begin

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