reactos/subsystems/ntvdm/emulator.c

/*
 * COPYRIGHT:       GPL - See COPYING in the top level directory
 * PROJECT:         ReactOS Virtual DOS Machine
 * FILE:            emulator.c
 * PURPOSE:         Minimal x86 machine emulator for the VDM
 * PROGRAMMERS:     Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
 */

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

#define NDEBUG

#include "emulator.h"
#include "bios.h"
#include "dos.h"
#include "vga.h"
#include "pic.h"
#include "ps2.h"
#include "timer.h"

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

FAST486_STATE EmulatorContext;

static BOOLEAN A20Line = FALSE;

/* PRIVATE FUNCTIONS **********************************************************/

static VOID WINAPI EmulatorReadMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
{
    UNREFERENCED_PARAMETER(State);

    /* If the A20 line is disabled, mask bit 20 */
    if (!A20Line) Address &= ~(1 << 20);

    /* Make sure the requested address is valid */
    if ((Address + Size) >= MAX_ADDRESS) return;

    /* Read the data from the virtual address space and store it in the buffer */
    RtlCopyMemory(Buffer, (LPVOID)((ULONG_PTR)BaseAddress + Address), Size);

    /* Check if we modified the console video memory */
    if (((Address + Size) >= VgaGetVideoBaseAddress())
        && (Address < VgaGetVideoLimitAddress()))
    {
        DWORD VgaAddress = max(Address, VgaGetVideoBaseAddress());
        LPBYTE VgaBuffer = (LPBYTE)((ULONG_PTR)Buffer + VgaAddress - Address);

        /* Read from the VGA memory */
        VgaReadMemory(VgaAddress, VgaBuffer, Size);
    }
}

static VOID WINAPI EmulatorWriteMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
{
    UNREFERENCED_PARAMETER(State);

    /* If the A20 line is disabled, mask bit 20 */
    if (!A20Line) Address &= ~(1 << 20);

    /* Make sure the requested address is valid */
    if ((Address + Size) >= MAX_ADDRESS) return;

    /* Make sure we don't write to the ROM area */
    if ((Address + Size) >= ROM_AREA_START && (Address < ROM_AREA_END)) return;

    /* Read the data from the buffer and store it in the virtual address space */
    RtlCopyMemory((LPVOID)((ULONG_PTR)BaseAddress + Address), Buffer, Size);

    /* Check if we modified the console video memory */
    if (((Address + Size) >= VgaGetVideoBaseAddress())
        && (Address < VgaGetVideoLimitAddress()))
    {
        DWORD VgaAddress = max(Address, VgaGetVideoBaseAddress());
        LPBYTE VgaBuffer = (LPBYTE)((ULONG_PTR)Buffer + VgaAddress - Address);

        /* Write to the VGA memory */
        VgaWriteMemory(VgaAddress, VgaBuffer, Size);
    }
}

static VOID WINAPI EmulatorReadIo(PFAST486_STATE State, ULONG Port, PVOID Buffer, ULONG Size)
{
    LPBYTE Address = (LPBYTE)Buffer;

    UNREFERENCED_PARAMETER(State);
    UNREFERENCED_PARAMETER(Size);

    switch (Port)
    {
        case PIC_MASTER_CMD:
        case PIC_SLAVE_CMD:
        {
            *Address = PicReadCommand(Port);
            break;
        }

        case PIC_MASTER_DATA:
        case PIC_SLAVE_DATA:
        {
            *Address = PicReadData(Port);
            break;
        }

        case PIT_DATA_PORT(0):
        case PIT_DATA_PORT(1):
        case PIT_DATA_PORT(2):
        {
            *Address = PitReadData(Port - PIT_DATA_PORT(0));
            break;
        }

        case PS2_CONTROL_PORT:
        {
            *Address = KeyboardReadStatus();
            break;
        }

        case PS2_DATA_PORT:
        {
            *Address = KeyboardReadData();
            break;
        }

        case VGA_AC_WRITE:
        case VGA_AC_READ:
        case VGA_SEQ_INDEX:
        case VGA_SEQ_DATA:
        case VGA_DAC_READ_INDEX:
        case VGA_DAC_WRITE_INDEX:
        case VGA_DAC_DATA:
        case VGA_MISC_READ:
        case VGA_MISC_WRITE:
        case VGA_CRTC_INDEX:
        case VGA_CRTC_DATA:
        case VGA_GC_INDEX:
        case VGA_GC_DATA:
        case VGA_STAT_MONO:
        case VGA_STAT_COLOR:
        {
            *Address = VgaReadPort(Port);
            break;
        }

        default:
        {
            DPRINT1("Read from unknown port: 0x%X\n", Port);
        }
    }
}

static VOID WINAPI EmulatorWriteIo(PFAST486_STATE State, ULONG Port, PVOID Buffer, ULONG Size)
{
    BYTE Byte = *(LPBYTE)Buffer;

    UNREFERENCED_PARAMETER(State);
    UNREFERENCED_PARAMETER(Size);

    switch (Port)
    {
        case PIT_COMMAND_PORT:
        {
            PitWriteCommand(Byte);
            break;
        }

        case PIT_DATA_PORT(0):
        case PIT_DATA_PORT(1):
        case PIT_DATA_PORT(2):
        {
            PitWriteData(Port - PIT_DATA_PORT(0), Byte);
            break;
        }

        case PIC_MASTER_CMD:
        case PIC_SLAVE_CMD:
        {
            PicWriteCommand(Port, Byte);
            break;
        }

        case PIC_MASTER_DATA:
        case PIC_SLAVE_DATA:
        {
            PicWriteData(Port, Byte);
            break;
        }

        case PS2_CONTROL_PORT:
        {
            KeyboardWriteCommand(Byte);
            break;
        }

        case PS2_DATA_PORT:
        {
            KeyboardWriteData(Byte);
            break;
        }

        case VGA_AC_WRITE:
        case VGA_AC_READ:
        case VGA_SEQ_INDEX:
        case VGA_SEQ_DATA:
        case VGA_DAC_READ_INDEX:
        case VGA_DAC_WRITE_INDEX:
        case VGA_DAC_DATA:
        case VGA_MISC_READ:
        case VGA_MISC_WRITE:
        case VGA_CRTC_INDEX:
        case VGA_CRTC_DATA:
        case VGA_GC_INDEX:
        case VGA_GC_DATA:
        case VGA_STAT_MONO:
        case VGA_STAT_COLOR:
        {
            VgaWritePort(Port, Byte);
            break;
        }

        default:
        {
            DPRINT1("Write to unknown port: 0x%X\n", Port);
        }
    }
}

VOID WINAPI ControlBop(LPWORD Stack);
static VOID WINAPI EmulatorBiosOperation(PFAST486_STATE State, UCHAR BopCode)
{
    WORD StackSegment, StackPointer;
    LPWORD Stack;

    /* Get the SS:SP */
    StackSegment = State->SegmentRegs[FAST486_REG_SS].Selector;
    StackPointer = State->GeneralRegs[FAST486_REG_ESP].LowWord;

    /* Get the stack */
    Stack = (LPWORD)SEG_OFF_TO_PTR(StackSegment, StackPointer);

    switch (BopCode)
    {
        case EMULATOR_INT_BOP:
            ControlBop(Stack);
            break;

        default:
            DPRINT1("Invalid BOP code %u\n", BopCode);
            break;
    }
}

static VOID WINAPI EmulatorIdle(PFAST486_STATE State)
{
}

static UCHAR WINAPI EmulatorIntAcknowledge(PFAST486_STATE State)
{
    UNREFERENCED_PARAMETER(State);

    /* Get the interrupt number from the PIC */
    return PicGetInterrupt();
}

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

BOOLEAN EmulatorInitialize()
{
    /* Allocate memory for the 16-bit address space */
    BaseAddress = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, MAX_ADDRESS);
    if (BaseAddress == NULL) return FALSE;

    /* Set the callbacks */
    EmulatorContext.MemReadCallback  = EmulatorReadMemory;
    EmulatorContext.MemWriteCallback = EmulatorWriteMemory;
    EmulatorContext.IoReadCallback   = EmulatorReadIo;  // Must be != NULL
    EmulatorContext.IoWriteCallback  = EmulatorWriteIo; // Must be != NULL
    EmulatorContext.IdleCallback     = EmulatorIdle;    // Must be != NULL
    EmulatorContext.BopCallback      = EmulatorBiosOperation;
    EmulatorContext.IntAckCallback   = EmulatorIntAcknowledge;

    /* Reset the CPU */
    Fast486Reset(&EmulatorContext);

    /* Enable interrupts */
    EmulatorSetFlag(EMULATOR_FLAG_IF);

    return TRUE;
}

VOID EmulatorSetStack(WORD Segment, DWORD Offset)
{
    Fast486SetStack(&EmulatorContext, Segment, Offset);
}

// FIXME: This function assumes 16-bit mode!!!
VOID EmulatorExecute(WORD Segment, WORD Offset)
{
    /* Tell Fast486 to move the instruction pointer */
    Fast486ExecuteAt(&EmulatorContext, Segment, Offset);
}

VOID EmulatorInterrupt(BYTE Number)
{
    /* Call the Fast486 API */
    Fast486Interrupt(&EmulatorContext, Number);
}

VOID EmulatorInterruptSignal(VOID)
{
    /* Call the Fast486 API */
    Fast486InterruptSignal(&EmulatorContext);
}

ULONG EmulatorGetRegister(ULONG Register)
{
    if (Register < EMULATOR_REG_ES)
    {
        return EmulatorContext.GeneralRegs[Register].Long;
    }
    else
    {
        return EmulatorContext.SegmentRegs[Register - EMULATOR_REG_ES].Selector;
    }
}

VOID EmulatorSetRegister(ULONG Register, ULONG Value)
{
    if (Register < EMULATOR_REG_ES)
    {
        EmulatorContext.GeneralRegs[Register].Long = Value;
    }
    else
    {
        Fast486SetSegment(&EmulatorContext, Register - EMULATOR_REG_ES, (USHORT)Value);
    }
}

ULONG EmulatorGetProgramCounter(VOID)
{
    return EmulatorContext.InstPtr.Long;
}

BOOLEAN EmulatorGetFlag(ULONG Flag)
{
    return (EmulatorContext.Flags.Long & Flag) ? TRUE : FALSE;
}

VOID EmulatorSetFlag(ULONG Flag)
{
    EmulatorContext.Flags.Long |= Flag;
}

VOID EmulatorClearFlag(ULONG Flag)
{
    EmulatorContext.Flags.Long &= ~Flag;
}

VOID EmulatorStep(VOID)
{
    /* Dump the state for debugging purposes */
    // Fast486DumpState(&EmulatorContext);

    /* Execute the next instruction */
    Fast486StepInto(&EmulatorContext);
}

VOID EmulatorCleanup(VOID)
{
    /* Free the memory allocated for the 16-bit address space */
    if (BaseAddress != NULL) HeapFree(GetProcessHeap(), 0, BaseAddress);
}

VOID EmulatorSetA20(BOOLEAN Enabled)
{
    A20Line = Enabled;
}

/* EOF */