;实训汇编语言以格式“SUNXXXX”显示一段英文中SUN出现的次数。 

data segment

 STO db 100 dup(?)

 Tip db 'Please enter a sentence include SUN:',13,10,'$'

 SUN db 13,10,'SUN'

 NUM db 4 dup(?),'$'

data ends

stack segment stack 

 str dw 256 dup(?)

stack ends

code segment

 main proc far

 assume ds:data,cs:code,ss:stack

start:

 push ds

 sub ax,ax

 push ax

 mov ax,data

 mov ds,ax

 mov ax,stack

 mov ss,ax

 lea dx,Tip

 mov ah,9

 int 21h

 lea dx,STO

 mov [STO],100

 mov ah,0ah

 int 21h

 mov cx,word ptr[STO+1]

 mov ax,0

 mov bx,2

L1:

 cmp [STO+bx],'S'

 je L2

 inc bx

 loop L1

 jmp next

L2:

 inc bx

 cmp [STO+bx],'U'

 je L3

 dec cx

 jmp L5

L3:

 inc bx

 cmp [STO+bx],'N'

 je L4

 sub cx,2

 jmp L5

L4:

 inc ax

L5:inc bx

 dec cx

 jnz L1

next:

 sub ax,2

 mov ch,4

 mov cl,4

 lea bx,NUM

L6:

 rol ax,cl

 mov dx,ax

 and dx,0fH

 add dl,30h

 cmp dl,39h

 jle L7

 add dl,07h

L7:

 mov [bx],dl

 inc bx

 dec ch

 jnz L6

L8:

 lea dx,SUN

 mov ah,9

 int 21h

 ret

main endp

code ends

 end start