String operation instruction 2
1. movs
; multi-segment executable file template.
data segment
; add your data here!
pkey db "press any key...$"
str1 db "howbin"
str2 db 6 dup(0)
ends
stack segment
dw 128 dup(0)
ends
code segment
start:
; set segment registers:
mov ax, data
mov ds, ax
mov es, ax
;1 设置源地址寄存器
lea si,str1;
;2 设置目的寄存器
lea di,str2;
;3.设置方向
cld ;std
;4.设置循环次数
mov cx, 6;
;5.重复头
rep movsb;
lea dx, str2
mov ah, 9
int 21h ; output string at ds:dx
; wait for any key....
mov ah, 1
int 21h
mov ax, 4c00h ; exit to operating system.
int 21h
ends
end start ; set entry point and stop the assembler.
2 stack
; multi-segment executable file template.
data segment
; add your data here!
pkey db "press any key...$"
str1 db 6 dup(0)
ends
stack segment
dw 128 dup(0)
ends
code segment
start:
; set segment registers:
mov ax, data
mov ds, ax
mov es, ax
; add your code here
;1.选型 stos stosb
;2.设置AL/AL填充物 al 源
mov al，'h';
;3. 设置目的
lea di, str1
;4.设置方向
cld
;5.设置次数
mov cx,0
mov cl,6
;6.设置重复头
rep stosb;
lea dx, pkey
mov ah, 9
int 21h ; output string at ds:dx
; wait for any key....
mov ah, 1
int 21h
mov ax, 4c00h ; exit to operating system.
int 21h
ends
end start ; set entry point and stop the assembler.
3 lods
; multi-segment executable file template.
data segment
; add your data here!
pkey db "press any key...$"
block db -1,-2,-3,0,1,2,3,4
count equ 8
dplus db count dup(0)
ends
stack segment
dw 128 dup(0)
ends
code segment
start:
; set segment registers:
mov ax, data
mov ds, ax
mov es, ax
; add your code here
;从字符串block中取正数存入字节串dplus中
;1. 确定取出 lodsb 确定放入 stos
;2. 设置源头 si 目的 di
lea si,block
lea di,dplus
;3. 设置方向
cld
;4. 设置次数
mov cx,0;
mov cl,count;
again:
lodsb;
cmp al,0
jle next;
stosb
next:
loop again;
lea dx, pkey
mov ah, 9
int 21h ; output string at ds:dx
; wait for any key....
mov ah, 1
int 21h
mov ax, 4c00h ; exit to operating system.
int 21h
ends
end start ; set entry point and stop the assembler.
4 cmps string comparison instruction
;比较等长俩个字符串，判断他们是否相等
; multi-segment executable file template.
data segment
; add your data here!
pkey db "press any key...$"
str1 db "abc"
str2 db "abc"
result db dub(0);
ends
stack segment
dw 128 dup(0)
ends
code segment
start:
; set segment registers:
mov ax, data
mov ds, ax
mov es, ax
mov result,0
;1.选择cmps
;2.设置源与目的
lea si,str1;
lea di,str2
;3.设置方向
cld
;4.设置次数
mov cx,0;
mov cl,3
;5.执重复头
repe cmpsb;
;6.判断
jnz next;
mov result,1
next:
lea dx, pkey
mov ah, 9
int 21h ; output string at ds:dx
; wait for any key....
mov ah, 1
int 21h
mov ax, 4c00h ; exit to operating system.
int 21h
ends
end start ; set entry point and stop the assembler.5 scas
;从一个字符串中查找一个指定字符
lea di,string
mov al, '' ;20h 空格
mov cl, sizeof string
cld ;设置方向
repnz scasb
jz found
.....
found:....
enter code hereSummary 6
1. 串操作，确定指令
2. 根据串的位置准备ds,es(ds可超越，但是es不可以)
3. 利用了lea,或者 设置offset si,di
4. 利用 sizeof lenghof 设置cx
5. 选择合适的rep
6. 设置不同分支程序（针对repz或者repnz）