/*
 * COPYRIGHT:       GPL - See COPYING in the top level directory
 * PROJECT:         ReactOS Virtual DOS Machine
 * FILE:            int32.c
 * PURPOSE:         32-bit Interrupt Handlers
 * PROGRAMMERS:     Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
 *                  Hermes Belusca-Maito (hermes.belusca@sfr.fr)
 */

/* INCLUDES *******************************************************************/

// #define NDEBUG

#include "emulator.h"
#include "int32.h"

#include "bop.h"

/* PRIVATE VARIABLES **********************************************************/

/*
 * This is the list of registered 32-bit Interrupt handlers.
 */
EMULATOR_INT32_PROC Int32Proc[EMULATOR_MAX_INT32_NUM] = { NULL };

/* BOP Identifiers */
#define BOP_CONTROL             0xFF    // Control BOP Handler
    #define BOP_CONTROL_DEFFUNC 0x00    // Default Control BOP Function

/* 32-bit Interrupt dispatcher function code for the Control BOP Handler */
#define BOP_CONTROL_INT32       0xFF

/* PUBLIC FUNCTIONS ***********************************************************/

VOID WINAPI Int32Dispatch(LPWORD Stack)
{
    /* Get the interrupt number */
    BYTE IntNum = LOBYTE(Stack[STACK_INT_NUM]);

    /* Call the 32-bit Interrupt handler */
    if (Int32Proc[IntNum] != NULL)
        Int32Proc[IntNum](Stack);
    else
        DPRINT("Unhandled 32-bit interrupt: 0x%02X, AX = 0x%04X\n", IntNum, getAX());
}

VOID WINAPI ControlBop(LPWORD Stack)
{
    /* Get the Function Number and skip it */
    BYTE FuncNum = *(PBYTE)SEG_OFF_TO_PTR(getCS(), getIP());
    setIP(getIP() + 1);

    if (FuncNum == BOP_CONTROL_INT32)
        Int32Dispatch(Stack);
    else
        DPRINT("Unassigned Control BOP Function: 0x%02X\n", FuncNum);
}

VOID InitializeInt32(WORD BiosSegment)
{
    //
    // WARNING WARNING!!
    //
    // If you modify the code stubs here, think also
    // about updating them in callback.c too!!
    //

    LPDWORD IntVecTable = (LPDWORD)BaseAddress;
    LPBYTE  BiosCode    = (LPBYTE)SEG_OFF_TO_PTR(BiosSegment, 0);
    USHORT i;
    WORD BopSeqOffset, Offset = 0;

    /* Generate ISR stubs and fill the IVT */
    for (i = 0x00; i <= 0xFF; i++)
    {
        Offset = INT_HANDLER_OFFSET + (i << 4);
        IntVecTable[i] = MAKELONG(Offset, BiosSegment);

        BiosCode[Offset++] = 0xFA; // cli

        BiosCode[Offset++] = 0x6A; // push i
        BiosCode[Offset++] = (UCHAR)i;

        BopSeqOffset = COMMON_STUB_OFFSET - (Offset + 3);

        BiosCode[Offset++] = 0xE9; // jmp near BOP_SEQ
        BiosCode[Offset++] = LOBYTE(BopSeqOffset);
        BiosCode[Offset++] = HIBYTE(BopSeqOffset);
    }

    /* Write the common stub code */
    Offset = COMMON_STUB_OFFSET;

// BOP_SEQ:
    BiosCode[Offset++] = 0xF8; // clc

    BiosCode[Offset++] = LOBYTE(EMULATOR_BOP);  // BOP sequence
    BiosCode[Offset++] = HIBYTE(EMULATOR_BOP);
    BiosCode[Offset++] = BOP_CONTROL;           // Control BOP
    BiosCode[Offset++] = BOP_CONTROL_INT32;     // 32-bit Interrupt dispatcher

    BiosCode[Offset++] = 0x73; // jnc EXIT (offset +4)
    BiosCode[Offset++] = 0x04;

    BiosCode[Offset++] = 0xFB; // sti

    // HACK: The following instruction should be HLT!
    BiosCode[Offset++] = 0x90; // nop

    BiosCode[Offset++] = 0xEB; // jmp BOP_SEQ (offset -11)
    BiosCode[Offset++] = 0xF5;

// EXIT:
    BiosCode[Offset++] = 0x44; // inc sp
    BiosCode[Offset++] = 0x44; // inc sp

    BiosCode[Offset++] = 0xCF; // iret

    /* Register the Control BOP */
    RegisterBop(BOP_CONTROL, ControlBop);
}

VOID RegisterInt32(BYTE IntNumber, EMULATOR_INT32_PROC IntHandler)
{
    Int32Proc[IntNumber] = IntHandler;
}

/* EOF */