#include "dos.h"

struct INTERRUPT

{

unsigned ax,bx,cx,dx,cs,ip,es,ds,bp,si,di,fl;

};

void interrupt hdprot(struct INTERRUPT);

void interrupt (*prev)();

main()

{

//AIM : to write protect the hard disk

unsigned long far *inthd;

inthd=(unsigned long far*)(0x13*4);

prev=(void (interrupt far*)())*inthd;

*inthd=(unsigned long)hdprot;

keep(0,500);

return 0;

}

void interrupt hdprot(struct INTERRUPT r)

{

if((_AH==3)|(_AH==5)|(_AH=0x0b))//if write, format, or long write

{

asm stc; //set carry , saying that write operation failed

_FLAGS=r.fl;

//asm pushf;

//asm pop r.fl; // both thease to move flag into r.flag

return;

}

_AX=r.ax;

_BX=r.bx;

_CX=r.cx;

_DX=r.dx;

_ES=r.es;

(*prev)();

//asm pushf;

//asm pop r.fl;

_FLAGS=r.fl;

r.es=_ES;

r.dx=_DX;

r.cx=_CX;

r.bx=_BX;

r.ax=_AX;

}//void inturrept hdprot()