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#define PIC_MASTER_COMMAND_PORT		0x20
#define PIC_MASTER_DATA_PORT		PIC_MASTER_COMMAND_PORT+1
#define PIC_SLAVE_COMMAND_PORT		0xA0
#define PIC_SLAVE_DATA_PORT		PIC_SLAVE_COMMAND_PORT+1
#define PIC_ICW1_COMMAND		0x11
#define PIC_ICW4_SLAVE			0x01
#define PIC_ICW4_MASTER			0x05

#define PIC_ICW2_MASTER			0x20
#define PIC_ICW2_SLAVE			0x28
#define PIC_ICW3_MASTER			0x04 //SLAVE's PIN NO. 
#define PIC_ICW3_SLAVE			0x02 //Master's PIN NO, connected to slave.

outb(PIC_MASTER_COMMAND_PORT,PIC_ICW1_COMMAND);
  outb(PIC_SLAVE_COMMAND_PORT,PIC_ICW1_COMMAND);
  outb(PIC_MASTER_DATA_PORT,PIC_ICW2_MASTER);
  outb(PIC_SLAVE_DATA_PORT,PIC_ICW2_SLAVE);
  outb(PIC_MASTER_DATA_PORT,PIC_ICW3_MASTER);
  outb(PIC_SLAVE_DATA_PORT,PIC_ICW3_SLAVE);
  
  outb(PIC_MASTER_DATA_PORT,PIC_ICW4_MASTER);
  outb(PIC_SLAVE_DATA_PORT,PIC_ICW4_SLAVE);
  
  //enable all interrupts
  outb(PIC_MASTER_DATA_PORT,0xFD);
  outb(PIC_SLAVE_DATA_PORT,0x00);

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void isr_handler(PushRegisters *regs)
{
  unsigned int intrnum=regs->procpushed.intr_num;
  //printk("Will execute interrupt %d\n",intrnum);
  if( handlers[intrnum].handler!=NULL)
  {
      handlers[intrnum].regs=*regs;
      //Put a spinlock above this line when handling SMP.
      handlers[intrnum].flags=ISR_BUSY;
      //this handler shall be scheduled based on the flags.
      //if(!handlers[intr_num].flags==ISR_BUSY)
      handlers[intrnum].handler(&handlers[intrnum].regs); //call isr.
      //we'll need to find a way to declare that an isr is free to be reloaded 
      //with another ISR handler or that it may be called.
      //currently since interrupts get disabled so ISR gets executed always.
      handlers[intrnum].flags=ISR_FREE;
  }
  else
  {
      handleExceptions(regs);
  }
  if(intrnum >31 && intrnum <40)
  {
    printk("sending master eoi and masking forever.\n");
    if(intrnum==33) inb(0x60);//read from keyboard.
    //outb(PIC_MASTER_DATA_PORT,1<<(intrnum-32));
    outb(PIC_MASTER_COMMAND_PORT,0x20); //send EOI to master.
  }
  else if(intrnum >=40)
  {
    printk("sending both eoi\n");
    outb(PIC_SLAVE_COMMAND_PORT,0x20); //Send EOI to slave.
    outb(PIC_MASTER_COMMAND_PORT,0x20); //Send EOI to master.
  }
}