%macro scall 4 
    mov rax,%1
    mov rdi,%2
    mov rsi,%3
    mov rdx,%4
    syscall
%endmacro

section .data 
    msg db"Machine is in Protected mode",10
    msglen equ $-msg
    msg1 db"Machine is not in Protected mode"
    msg1len equ $-msg1
    msg2 db 10,"Contents of GDTR: "
    msg2len equ $-msg2
    msg3 db "  : "
    msg3len equ $-msg3

section .bss
    msw resb 4 
    gdtr resb 6
    result resb 6

section .text
global _start
_start:
    smsw eax 
    bt eax,0 
    jc next
    scall 1,1,msg1,msg1len
    jmp exit
    next:
    scall 1,1,msg,msglen
    mov esi,[gdtr]

    sgdt [gdtr] 
    scall 1,1,msg2,msg2len
    mov bx,word[gdtr+4] ;32 bits reserved for base
    call conversion
    mov bx,word[gdtr+2] ;16 bits reserved for limit
    call conversion
    scall 1,1,msg3,msg3len
    mov bx,word[gdtr]
    call conversion
    exit:
    scall 60,0,0,0
    
    ;Hex to Ascii code conversion method
    conversion:
    mov esi,result
    mov cl,4
    up:rol ax,4 
    mov dx,bx 
    and bx,0fh
    cmp bl,09h 
    jbe skip 
    add bl,07h
    skip:add bl, 30h ;for value betwwn 0 to 9
    mov [esi],bl
    inc esi
    mov bx,dx
    dec cl
    
    jnz up ;jump not zero
    scall 1,1,result,4
    ret