//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Desc:  Interrupt related functions                                        //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2019 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K is free software: you can redistribute it and/or modify              //
//  it under the terms of the GNU General Public License as published by      //
//  the Free Software Foundation, either version 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K is distributed in the hope that it will be useful,                   //
//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
//  GNU General Public License for more details.                              //
//                                                                            //
//  You should have received a copy of the GNU General Public License         //
//  along with OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <kernel/base.h>
#include <kernel/idt.h>
#include <kernel/boot.h>
#include <kernel/iomisc.h>
#include <extras/buf.h>

IdtEntry_t idt[256] = { 0 };
IdtPtr_t idtPtr;

IRQList_t irqList = { 0 };


//
// Registers an isr with his IRQ to handle driver interrupts
//
void IdtRegisterIrq(void (*isr)(void), uchar irq, uchar flags)
{
    uchar n = irqList.n;

    KalAssert(idt[0].flags==0); // IDT uninitialized

    if ((n == 224))             // IRQs not filled
        KeStartPanic("[IdtRegisterIrq] Cannot register IRQ %c function %p !",
                     irq,
                     isr
                     );

    irqList.entry[n].isr = isr;
    irqList.entry[n].irq = irq;
    irqList.entry[n].flags = flags;
    irqList.n++;
}

//
// Installs the IDT in order to activate the interrupts handling
//
void IdtSetup(void)
{
    // XXX detect the APIC with cpuid !
    EnablePIC();

    ushort codeSeg = (ushort)(ulong)BtLoaderInfo.codeSegment;

    // Set IDT ptr
    idtPtr.limit = (sizeof(IdtEntry_t) * 256) - 1;
    idtPtr.base = &idt;

    // Set IDT Exception Gates
    IdtSetGate(0, (ulong)isr0, codeSeg, 0x8E);
    IdtSetGate(1, (ulong)isr1, codeSeg, 0x8E);
    IdtSetGate(2, (ulong)isr2, codeSeg, 0x8E);
    IdtSetGate(3, (ulong)isr3, codeSeg, 0x8E);
    IdtSetGate(4, (ulong)isr4, codeSeg, 0x8E);
    IdtSetGate(5, (ulong)isr5, codeSeg, 0x8E);
    IdtSetGate(6, (ulong)isr6, codeSeg, 0x8E);
    IdtSetGate(7, (ulong)isr7, codeSeg, 0x8E);
    IdtSetGate(8, (ulong)isr8, codeSeg, 0x8E);
    IdtSetGate(9, (ulong)isr9, codeSeg, 0x8E);
    IdtSetGate(10, (ulong)isr10, codeSeg, 0x8E);
    IdtSetGate(11, (ulong)isr11, codeSeg, 0x8E);
    IdtSetGate(12, (ulong)isr12, codeSeg, 0x8E);
    IdtSetGate(13, (ulong)isr13, codeSeg, 0x8E);
    IdtSetGate(14, (ulong)isr14, codeSeg, 0x8E);
    IdtSetGate(15, (ulong)isr15, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(16, (ulong)isr16, codeSeg, 0x8E);
    IdtSetGate(17, (ulong)isr17, codeSeg, 0x8E);
    IdtSetGate(18, (ulong)isr18, codeSeg, 0x8E);
    IdtSetGate(19, (ulong)isr19, codeSeg, 0x8E);
    IdtSetGate(20, (ulong)isr20, codeSeg, 0x8E);
    IdtSetGate(21, (ulong)isr21, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(22, (ulong)isr22, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(23, (ulong)isr23, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(24, (ulong)isr24, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(25, (ulong)isr25, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(26, (ulong)isr26, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(27, (ulong)isr27, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(28, (ulong)isr28, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(29, (ulong)isr29, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(30, (ulong)isr30, codeSeg, 0x8E);  // INTEL RESERVED
    IdtSetGate(31, (ulong)isr31, codeSeg, 0x8E);  // INTEL RESERVED

    // Set the IRQ Driver Gates
    for (int i = 0 ; i < irqList.n ; i++) {
        IdtSetGate(
                   irqList.entry[i].irq,
                   (ulong)irqList.entry[i].isr,
                   codeSeg,
                   irqList.entry[i].flags
                   );
    }

    // Load IDT
    IdtInit();
    DebugLog("[IdtSetup] Initialized !\n");
}

//
// Set an interrupt gate
//
void IdtSetGate(uchar rank, ulong base, ushort selector, uchar flags)
{
    // Set Base Address
    idt[rank].baseLow = base & 0xFFFF;
    idt[rank].baseMid = (base >> 16) & 0xFFFF;
    idt[rank].baseHigh = (base >> 32) & 0xFFFFFFFF;

    // Set Selector
    idt[rank].selector = selector;
    idt[rank].flags = flags;

    // Set Reserved Areas to Zero
    idt[rank].reservedIst = 0;
    idt[rank].reserved = 0;
}

//
// Enable and initializes the PIC to work correctly
//
static void EnablePIC(void)
{
    // Set ICW1 - begin init of the PIC
    IoWriteByteOnPort(0x20, 0x11);
    IoWriteByteOnPort(0xa0, 0x11);

    // Set ICW2 (IRQ base offsets)
    IoWriteByteOnPort(0x21, 0x20); //0x20 is the first free interrupt
    IoWriteByteOnPort(0xa1, 0x28);

    // Set ICW3
    IoWriteByteOnPort(0x21, 0x0);
    IoWriteByteOnPort(0xa1, 0x0);

    // Set ICW4
    IoWriteByteOnPort(0x21, 0x1);
    IoWriteByteOnPort(0xa1, 0x1);

    // Set OCW1 (interrupt masks)
    IoWriteByteOnPort(0x21, 0xff);
    IoWriteByteOnPort(0xa1, 0xff);
}

//
// Ends the current interrupt handling
//
void SendEOItoPIC(uchar isr)
{
    if(isr >= 8)
        IoWriteByteOnPort(0xa0,0x20);

    IoWriteByteOnPort(0x20,0x20);
}

//
// The main exception handler
//
void IdtHandler(ulong intNo)
{
    int irrecoverable = 0;
    char *exceptionMsg = "Unhandled ISR exception";

    if (intNo == 0 || intNo == 6 || intNo == 8 || intNo == 13) irrecoverable++;

    if (intNo < 32) exceptionMsg = IsrExceptions[intNo];

    if (irrecoverable) {
        KeStartPanic("[ISR 0x%x] Irrecoverable %s\n", intNo, exceptionMsg);
    } else {
        bprintf(BStdOut, "[ISR 0x%x] %s\n", intNo, exceptionMsg);
        SendEOItoPIC(intNo);
    }
}