.model small
.stack 100
.data 

mess1 db "(E) Encrypt text file.",10,13,'$'
mess2 db "(D) Decrypt text file.",10,13,'$'
mess3 db "(Q) quit.",10,13,'$'          
             
msg_one DB "Please enter your choice:",10,13,'$'
msg_inputfilename db ,10,13,"Please enter the name of the file to read data from :",10,13,'$'
msg_outputfilename db ,"Please enter the name of the file to write dana on :",10,13,'$'

 


fileNameBuff db 100, db 0, db 100 dup (?)
fileName db 100 dup (?) ;this since i want to copy the original statement to it.  

TEXT DB 250 DUP(?)
FHAND DW ?


.code

mov ax, @data
mov ds, ax 

start:

;set cursor 
mov dh, 0
mov dl, 0
call set_cursor 

call clear_screen

;display mess1 (encrypt text file)
mov ah, 09h
lea dx, mess1
int 21h


;display mess2 (decrypt text file)
lea dx, mess2
call print_message

;display mess3 (Quit)
lea dx, mess3
call print_message  


;display msg_one
lea dx, msg_one
call print_message 


mov ah, 01h
int 21h          ;the choice is stored in al register
        
cmp al, 'E'

je E 
jmp after_E

E: 
call E_procedure 
jmp start

after_E:  

cmp al, 'D'
je D 
jmp after_D
D:
call D_procedure
jmp start 

after_D:
cmp al, 'Q'
je end_program   

;note if user enter another char, just I will repeat the messages
jmp start


       
        

   




 
 







end_program:           
mov ah, 4ch
int 21h
          
          


                                                  ;Main procedures
;========================================================================================================== 

                                                  ;(1)E_procedure
;--------------------------------------------------------------------------------------------------------   

E_procedure proc  
    
    ;display msg_inputfilenaame     
    lea dx,msg_inputfilename    
    call print_message
    
    ;read the fileName from user

    lea dx, fileNameBuff
    mov ah, 0Ah
    int 21h    
    
    
    mov cl, [fileNameBuff + 1]  ;load actual length of the statement to cx register
     xor ch, ch  
     lea di, fileNameBuff
     inc di
     inc di  
     mov bx, cx
     mov [di+bx], 0
    
    
    
    
    call read_file
    
        
    
    
    
    ;Yanal you should put your code here to encrypt the file
    ;note, now deal with fileName variable 
    
    ret
endp

                                                  ;(2)D_procedure
;--------------------------------------------------------------------------------------------------------   
D_procedure proc   
    
    ;display msg_inputfilenaame     
    lea dx,msg_inputfilename    
    call print_message
    
    ;read the fileName from user

    lea dx, fileNameBuff
    mov ah, 0Ah
    int 21h 
    
     mov cl, [fileNameBuff + 1]  ;load actual length of the statement to cx register
     xor ch, ch  
     lea di, fileNameBuff
     inc di
     inc di  
     mov bx, cx
     mov [di+bx], 0
    
    
    
    
    call read_file
    
    
    
    ;Yanal you should put your code here to decrypt the file
    ;note, now deal with fileName variable
    
    ret 
endp



          
          
                                                       ;HELPING PROCEDURES
;==================================================================================================================================== 


                                     ; (1) Clear_screen
;------------------------------------------------------------------------------------------ 
; the following procedure clear screen and paint it 

proc clear_screen 
    push ax
    push bx
    push cx
    push dx 
    
    MOV AX, 0600H     
    MOV BH, 71h	; white BG (7), Blue text (1) 
    MOV CX, 0000h	; upper left  row:column
    MOV DX, 184Fh	; lower right  row:column
    INT 10H		; call 
    
    pop dx
    pop cx
    pop bx
    pop ax
    ret 
endp 




                                    
     
     
                                   ; (2) print_message
;-------------------------------------------------------------------------------------------

proc print_message  
    push ax
    
    mov ah, 09h
    int 21h
    
    pop ax
    
    ret 
endp 



                     
      
      
                                    ;(4) set_cursor
;-----------------------------------------------------------------------------------------  

;parameter(DH, DL) DH: row, DL: column
proc set_cursor 
    push ax
    push bx 
    
    mov bh, 00h
	mov ah, 02h
    int 10h 
	
	pop bx
	pop ax
    ret
endp 

                                     ;(5)read_file
;------------------------------------------------------------------------------------------------  
;this procedure read from file until end

read_file proc
    push ax
    push dx
    push si
    push cx
  
    MOV AH,3DH ; READ A FILE
    MOV AL,02
    LEA DX,fileNameBuff ; THE ADDRESS OF FILE NAME SHOULD BE IN DX
    inc dx
    inc dx
    INT 21H
    MOV FHAND,AX ;FILE HANDLE IS RETURNED IN AX
    MOV SI,0
    L:
    MOV AH,3FH ; THE FILE HANDLE
    MOV CX,1 ; NUMBER OF BYTES TO BE READ
    LEA DX,TEXT+SI ; THE ADDRESS OF DATA TO BE READ
    mov bx,FHAND
    INT 21H
    CMP AX,0
    JE EXIT
    INC SI
    JMP L
    EXIT:
    MOV BYTE PTR TEXT+SI,"$"
    MOV AH,3EH
    INT 21H
    


    pop cx
    pop si
    pop dx
    pop ax 

    ret
endp