file.asm

;Assembly code to write messages to file

section	.data
scoreMsg db "Your score was: " ;Message for score
scoreMsgLen equ $-scoreMsg ; Ge the persons name
saveMsg db "The score is written to file " ;Message for score
saveMsgLen equ $-saveMsg ; Ge the persons name
score db '9' ; the score
cr db 10 ; newline like endl in C++
fileName db 'output.txt'

section .bss
fileWrite resb 1 ; store the id for the file

section	.text
   global _start         ;must be declared for using gcc
_start:                  ;tell linker entry point
;; delete file at start
  mov eax, 10        ; system call 10 to delete file
  mov ebx, fileName ; file name to delete
  int 80h            ; interrupt     
    
   ;create the file
  mov  eax, 8 ; system call the create file
  mov  ebx, fileName ; name of file to be created
  mov  ecx, 0777        ;Set file permission
  int  80h            ;call interrupt
	
 mov [fileWrite], eax ; File identifier
    
   ; write score and message to file
 mov	edx, scoreMsgLen        ;Size of message
 mov	ecx, scoreMsg         ;message to be written to file
 mov	ebx, [fileWrite]    ;file id for saving
 mov	eax,4            ;system call write
 int 80h             ;interrupt
 
	; write score in the file
   mov	edx, 1        ;Size of score in bytes
   mov	ecx, score         ;message to write
   mov	ebx, [fileWrite]    ;file descriptor 
   mov	eax,4            ;system call number (sys_write)
   int	0x80             ;call kernel
   
   ; write into the file newline
   mov	edx, 1        ;One bytes
   mov	ecx, cr        ;newline like endl in C++
   mov	ebx, [fileWrite]    ;file id
   mov	eax,4            ;system call for writing
   int	80h            ;interrupt
   
    ;close the file
   mov eax, 6 ; system call to close the file
   mov ebx, [fileWrite] ; file id
   int 80h; inteuupt
   ; write the message to screen that written information to file
   mov eax, 4
   mov ebx, 1
   mov ecx, saveMsg
   mov edx, saveMsgLen
   int  80h
   
   ; write the news line to screen.  Same as endl in C++
   mov eax, 4 ; System call the screen
   mov ebx, 1 ; standard out
   mov ecx, cr ; newline
   mov edx, 1; One byte is size
   int  80h ; interrupt
   ;exit program
   mov	eax,1 ;system call exit
   int	0x80  ;call interrupt