Added shutdown function

Author: Retr0-code

boot.asm

@@ -49,12 +49,13 @@ section .text:
     _stop:
         push msg2
         call _printformat
-        jmp $                       ; Stops the processor
+        call _shutdown
 
 
 ; Data Section
 %include "functions/io.asm"
 %include "functions/disk_mng.asm"
+%include "functions/shutdown.asm"
 
         msg1: db "Hello, There!\nDo You want to enter 32 bit mode?[Y]/[N](default=Y) \0" ; Printable string
         msg2: db "Goodby!\0"

functions/shutdown.asm

@@ -0,0 +1,21 @@
+global _shutdown
+
+section .text:
+    _shutdown:
+        mov al, 0x01        ; Connect to real mode interface
+        mov ah, 0x53        ; Use APM control
+        xor bx, bx          ; BX is BIOS id so it set to 0 
+        int 15h             ; Use BIOS interruption for additional functions
+    
+        mov al, 0x0e        ; Set APM version function
+        mov ah, 0x53        ; Use APM control
+        xor bx, bx          ; BX is BIOS id so it set to 0 
+        mov ch, 0x01        ; Set major APM version to 1
+        mov cl, 0x02        ; Set minor APM version to 2
+        int 15h             ; Use BIOS interruption for additional functions
+
+        mov al, 0x07        ; Set device state function
+        mov ah, 0x53        ; Use APM control
+        mov bx, 0x0001      ; Select all devices
+        mov cx, 0x03        ; Set shutdown mode
+        int 15h             ; Use BIOS interruption for additional functions