Njupt South Post collection_ Experiment 2

Implementation of user login authentication program
The experimental requirements ： After the program is executed , Give operation tips , Ask the user to type the user name and password ; The user is typing a password , The program does not echo typed characters ; Only when the user types the user name 、 The password string is the same as the string specified in the program , Show welcome screen , And back to DOS. The interface color is customized （ Color or black and white ）.

DATAS SEGMENT
	STR1 DB 'Please enter your username: $' 
	STR2 DB 0AH,0DH,'Please enter your password: $' 
	STR3 DB 0AH,0AH,'Input error!',0DH,0AH,'Please input again$'
	STR4 DB 'WELCOM!'
	BUF1 DB 15	; Store input user name 
		DB ?
		DB 15 DUP(?)
	BUF2 DB 15 DUP(?)
	USERNAME DB 'root'
	PASSWORD DB '123456'
DATAS ENDS

CODES SEGMENT
    ASSUME CS:CODES,DS:DATAS,ES:DATAS
START:
    MOV AX,DATAS
    MOV DS,AX
    MOV ES,AX
    MOV SI,0
BEG:
    ; Display prompt message 
    MOV AH,09H
    MOV DX,OFFSET STR1
    INT 21H
    ; enter one user name 
    MOV AH,0AH
    MOV DX,OFFSET BUF1
    INT 21H
    ; Display prompt message 
    MOV AH,09H
    MOV DX,OFFSET STR2
    INT 21H
    ; Input password 
INPUT:
	MOV AH,07H
	INT 21H
	MOV BUF2[SI],AL
	CMP AL,0DH
	JE OVER		; If enter enter , End of surface user input 
	INC SI
	MOV AH,02H
	MOV DL,'*'
	INT 21H
	JMP INPUT
OVER:
	; Determine if the user name is correct 
	MOV SI,OFFSET BUF1[2]
	MOV DI,OFFSET USERNAME
	MOV CX,4
	CLD
	REPZ CMPSB
	JNZ ERROR	; Incorrect user name 
	; Determine if the password is correct 
	MOV SI,OFFSET BUF2
	MOV DI,OFFSET PASSWORD
	MOV CX,6
	CLD
	REPZ CMPSB
	JNZ ERROR	; Incorrect password 
	; Show welcome screen 
	MOV AX,0003H
	INT 10H
	MOV AX,1301H
	MOV BH,0
	MOV BL,01001111B
	MOV CX,7
	MOV DH,12
	MOV DL,(80-7)/2
	MOV BP,OFFSET STR4
	INT 10H
	JMP RETURN
	; Display error 
ERROR:
	MOV AH,09H
    MOV DX,OFFSET STR3
    INT 21H
    JMP BEG
RETURN:
    MOV AH,4CH
    INT 21H
CODES ENDS
    END START