%macro  print   2
	mov 	rax,1		; Function 1 - write
  	mov 	rdi,1		; To stdout
   	mov 	rsi,%1		; String address
   	mov 	rdx,%2		; String size
   	syscall			; invoke operating system to WRITE
%endmacro

%macro  read   2
	mov 	rax,0		; Function 0 - Read
  	mov 	rdi,0		; from stdin
   	mov 	rsi,%1		; buffer address
   	mov 	rdx,%2		; buffer size
   	syscall			; invoke operating system to READ
%endmacro

section .data 
       m1 db 10d,"Enter String: "
        l1 equ $-m1
        m2 db 10d,"Length of String is: "
        l2 equ $-m2
        m3 db 10d,"Reversed String is: "
        l3 equ $-m3     
section .bss
        string resb 50
        string2 resb 50
        length resb 16
        answer resb 16
        
section .text
        global _start
_start:
print m1,l1
read string,50
;length is returned in rax
;decrement once to remove count of Enter character
        ;dec rax                 
        mov [length],rax
        print m2,l2
        mov rax,[length]
        
        mov rsi,answer+15
        mov rcx,16

loop1:	mov rdx,0
        mov rbx,16
        div rbx
        cmp dl,09h
        jbe skip1
        
        add dl,07h
skip1:	add dl,30h
        mov [rsi],dl
        
        dec rsi
        dec rcx
        jnz loop1
        print answer,16       



        mov rsi,string
        mov rdi,string2
        mov rcx,[length]
        add rdi,rcx
        dec rdi
        
loop2:  
        mov al,[rsi]        
        mov [rdi],al
        dec rdi
        inc rsi
        loop loop2
print m3,l3
        print string2,[length]


        mov rax,60
        mov rdx,0
        syscall