%macro scall 4
  mov rax, %1  ; func num for o/p data
  mov rdi, %2  ; file descriptor ID for monitor
  mov rsi, %3  ; starting address of string
  mov rdx, %4  ; number of bytes to be displayed
syscall  ; inbulit func
%endmacro
section .data
 msg db "The processor is in protected mode",10
 msglen equ $-msg
 msg1 db "The processor is in real mode",10
 msg1len equ $-msg1
 msg3 db 10,"Contents of GDTR: "
 msg3len equ $-msg3
 msg4 db 10,"Contents of IDTR: "
 msg4len equ $-msg4
 msg5 db 10,"Contents of LDTR: "
 msg5len equ $-msg5
 msg6 db 10,"Contents of the task register: "
 msg6len equ $-msg6
 msg7 db 10,"Contents of MSW: "
 msg7len equ $-msg7
 msg8 db 10,"------Exiting from the program!!-------"
 msg8len equ $-msg8
 msg9 db " : "
 msg9len equ $-msg9
 cnt2 db 04H
 newline db 10
section .bss
msw: 
 resd 1
 resw 1
g: 
 resd 1
 resw 1
 value resb 4
idtr: 
 resd 1
 resw 1
ldtr: 
 resw 1
 resw 1
tr resw 1
section .text
global _start
_start:
 smsw [msw]
 mov eax, dword[msw]
 bt eax,0 ;bit test if last PE bit=1 cy=1(protected mode)
 jc next
 scall 1,1,msg1,msg1len
 jmp EXIT
 next:
 scall 1,1,msg,msglen
 ;------gtdr contents---------
 scall 1,1,msg3,msg3len
 sgdt[g]   ;Stores the contents of the global descriptor table register (GDTR) in the destination operand. The destination operand specifies a 8-byte memory location. In ;64-bit mode, the operand size is fixed at 8+2 bytes.The instruction stores an 8-byte base ;and a 2-byte limit
 mov bx,word[g+4] ;BASE
 call conversion
 mov bx,word[g+2] ;LIMIT
 call conversion
 mov bx,word[g]
 scall 1,1,msg9,msg9len
 call conversion
 scall 1,1,newline,1
;-------IDTR contents----------
 scall 1,1,msg4,msg4len
 sidt[idtr]
 mov bx, word[idtr+4] ;BASE
 call conversion
 mov bx, word[idtr+2] ;LIMIT
 call conversion
 mov bx, word[idtr]
 scall 1,1,msg9,msg9len
 call conversion
 scall 1,1,newline,1
;---------LDTR contents---------
 scall 1,1,msg5,msg5len
 sldt[ldtr]
 mov bx,word[g]
 call conversion
 scall 1,1,newline,1
;-------MSW contents----------
 scall 1,1,msg7,msg7len
 mov bx, word[msw+2]
 call conversion
 mov bx, word[msw]
 call conversion
 scall 1,1,newline,1
;---------TR contents---------
 scall 1,1,msg6,msg6len
 mov bx,word[tr]
 call conversion
 scall 1,1,newline,1
 EXIT:
 scall 1,1,msg8,msg8len
 scall 1,1,newline,1
 mov rax,60
 mov rdi,0
 syscall
;----------HEX to ASCII conversion-------------
conversion:
 mov rdi,value
 mov byte[cnt2],4H
 aup:
 rol bx,04
 mov cl,bl
 and cl,0fH
 cmp cl,09H
 jbe ANEXT
 add cl,07H
ANEXT:
 add cl,30H
 mov byte[rdi],cl
 inc rdi
 dec byte[cnt2]
 JNZ aup
 scall 1,1,value,4
 ret