#include <system.h>
#include "pic.h"
#include "irq.h"
#include "../idt/idt.h"

/* These are own ISRs that point to our special IRQ handler
*  instead of the regular 'fault_handler' function */
extern void i86_irq0();
extern void i86_irq1();
extern void i86_irq2();
extern void i86_irq3();
extern void i86_irq4();
extern void i86_irq5();
extern void i86_irq6();
extern void i86_irq7();
extern void i86_irq8();
extern void i86_irq9();
extern void i86_irq10();
extern void i86_irq11();
extern void i86_irq12();
extern void i86_irq13();
extern void i86_irq14();
extern void i86_irq15();

/* This array is actually an array of function pointers. We use
*  this to handle custom IRQ handlers for a given IRQ */
void *IrqRoutines[16] =
{
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0
};

/* This installs a custom IRQ handler for the given IRQ */
void i86_IrqInstallHandler (int irq, void (*handler)(ISR_stack_regs *r))
{
      IrqRoutines[irq] = handler;
}

void i86_IrqUninstallHandler (int irq)
{
      IrqRoutines[irq] = 0;
}



/* We first remap the interrupt controllers, and then we install
*  the appropriate ISRs to the correct entries in the IDT. This
*  is just like installing the exception handlers */
void i86_IrqInstall()
{
      i86_PicRemap(32,40);
      
      i86_IdtSetGate(32, (unsigned)i86_irq0, 0x08, 0x8E);
      i86_IdtSetGate(33, (unsigned)i86_irq1, 0x08, 0x8E);
      i86_IdtSetGate(34, (unsigned)i86_irq2, 0x08, 0x8E);
      i86_IdtSetGate(35, (unsigned)i86_irq3, 0x08, 0x8E);
      i86_IdtSetGate(36, (unsigned)i86_irq4, 0x08, 0x8E);
      i86_IdtSetGate(37, (unsigned)i86_irq5, 0x08, 0x8E);
      i86_IdtSetGate(38, (unsigned)i86_irq6, 0x08, 0x8E);
      i86_IdtSetGate(39, (unsigned)i86_irq7, 0x08, 0x8E);
      i86_IdtSetGate(40, (unsigned)i86_irq8, 0x08, 0x8E);
      i86_IdtSetGate(41, (unsigned)i86_irq9, 0x08, 0x8E);
      i86_IdtSetGate(42, (unsigned)i86_irq10, 0x08, 0x8E);
      i86_IdtSetGate(43, (unsigned)i86_irq11, 0x08, 0x8E);
      i86_IdtSetGate(44, (unsigned)i86_irq12, 0x08, 0x8E);
      i86_IdtSetGate(45, (unsigned)i86_irq13, 0x08, 0x8E);
      i86_IdtSetGate(46, (unsigned)i86_irq14, 0x08, 0x8E);
      i86_IdtSetGate(47, (unsigned)i86_irq15, 0x08, 0x8E);
}

/* Each of the IRQ ISRs point to this function, rather than
*  the 'fault_handler' in 'isrs.c'. The IRQ Controllers need
*  to be told when you are done servicing them, so you need
*  to send them an "End of Interrupt" command (0x20). There
*  are two 8259 chips: The first exists at 0x20, the second
*  exists at 0xA0. If the second controller (an IRQ from 8 to
*  15) gets an interrupt, you need to acknowledge the
*  interrupt at BOTH controllers, otherwise, you only send
*  an EOI command to the first controller. If you don't send
*  an EOI, you won't raise any more IRQs */
void i86_IrqHandler (ISR_stack_regs *r)
{
      /* This is a blank function pointer */
      void (*handler)(ISR_stack_regs *r);
      
    /* Find out if we have a custom handler to run for this
    *  IRQ, and then finally, run it */
      handler = IrqRoutines[r->int_no - 32];
      if (handler) handler(r);
      
    /* If the IDT entry that was invoked was greater than 40
    *  (meaning IRQ8 - 15), then we need to send an EOI to
    *  the slave controller */
      if (r->int_no >=40) outportb(0x0A, 0x20);
      
    /* In either case, we need to send an EOI to the master
    *  interrupt controller too */
      outportb(0x20, 0x20);
}