/*
 * COPYRIGHT:       GPL - See COPYING in the top level directory
 * PROJECT:         ReactOS Virtual DOS Machine
 * FILE:            ps2.c
 * PURPOSE:         PS/2 controller emulation
 * PROGRAMMERS:     Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
 */

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

#define NDEBUG

#include "emulator.h"
#include "io.h"
#include "ps2.h"
#include "pic.h"

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

static BYTE KeyboardQueue[KEYBOARD_BUFFER_SIZE];
static BOOLEAN KeyboardQueueEmpty = TRUE;
static UINT KeyboardQueueStart = 0;
static UINT KeyboardQueueEnd = 0;
static BYTE KeyboardData = 0, KeyboardResponse = 0;
static BOOLEAN KeyboardReadResponse = FALSE, KeyboardWriteResponse = FALSE;
static BYTE KeyboardConfig = PS2_DEFAULT_CONFIG;
static HANDLE QueueMutex = NULL;
static HANDLE InputThread = NULL;

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

static BOOLEAN KeyboardQueuePush(BYTE ScanCode)
{
    BOOLEAN Result = TRUE;

    WaitForSingleObject(QueueMutex, INFINITE);

    /* Check if the keyboard queue is full */
    if (!KeyboardQueueEmpty && (KeyboardQueueStart == KeyboardQueueEnd))
    {
        Result = FALSE;
        goto Done;
    }

    /* Insert the value in the queue */
    KeyboardQueue[KeyboardQueueEnd] = ScanCode;
    KeyboardQueueEnd++;
    KeyboardQueueEnd %= KEYBOARD_BUFFER_SIZE;

    /* Since we inserted a value, it's not empty anymore */
    KeyboardQueueEmpty = FALSE;

Done:
    ReleaseMutex(QueueMutex);
    return Result;
}

static BOOLEAN KeyboardQueuePop(BYTE *ScanCode)
{
    BOOLEAN Result = TRUE;

    /* Make sure the keyboard queue is not empty (fast check) */
    if (KeyboardQueueEmpty) return FALSE;

    WaitForSingleObject(QueueMutex, INFINITE);

    /*
     * Recheck whether keyboard queue is not empty (it
     * may have changed after having grabbed the mutex).
     */
    if (KeyboardQueueEmpty)
    {
        Result = FALSE;
        goto Done;
    }

    /* Get the scan code */
    *ScanCode = KeyboardQueue[KeyboardQueueStart];

    /* Remove the value from the queue */
    KeyboardQueueStart++;
    KeyboardQueueStart %= KEYBOARD_BUFFER_SIZE;

    /* Check if the queue is now empty */
    if (KeyboardQueueStart == KeyboardQueueEnd)
    {
        KeyboardQueueEmpty = TRUE;
    }

Done:
    ReleaseMutex(QueueMutex);
    return Result;
}

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

BYTE WINAPI PS2ReadPort(ULONG Port)
{
    if (Port == PS2_CONTROL_PORT)
    {
        BYTE Status = 0;

        /* Set the first bit if the data can be read */
        if (KeyboardReadResponse || !KeyboardQueueEmpty) Status |= 1 << 0;

        /* Always set bit 2 */
        Status |= 1 << 2;

        /* Set bit 3 if the next byte goes to the controller */
        if (KeyboardWriteResponse) Status |= 1 << 3;

        return Status;
    }
    else if (Port == PS2_DATA_PORT)
    {
        /* If there was a response byte from the controller, return it */
        if (KeyboardReadResponse)
        {
            KeyboardReadResponse = FALSE;
            KeyboardData = KeyboardResponse;
        }

        return KeyboardData;
    }
    else return 0;
}

VOID WINAPI PS2WritePort(ULONG Port, BYTE Data)
{
    if (Port == PS2_CONTROL_PORT)
    {
        switch (Data)
        {
            /* Read configuration byte */
            case 0x20:
            {
                KeyboardResponse = KeyboardConfig;
                KeyboardReadResponse = TRUE;
                break;
            }

            /* Write configuration byte */
            case 0x60:
            /* Write controller output port */
            case 0xD1:
            /* Write keyboard output buffer */
            case 0xD2:
            /* Write mouse output buffer */
            case 0xD3:
            /* Write mouse input buffer */
            case 0xD4:
            {
                /* These commands require a response */
                KeyboardResponse = Data;
                KeyboardWriteResponse = TRUE;
                break;
            }

            /* Disable mouse */
            case 0xA7:
            {
                // TODO: Mouse support
                break;
            }

            /* Enable mouse */
            case 0xA8:
            {
                // TODO: Mouse support
                break;
            }

            /* Test mouse port */
            case 0xA9:
            {
                KeyboardResponse = 0;
                KeyboardReadResponse = TRUE;
                break;
            }

            /* Test PS/2 controller */
            case 0xAA:
            {
                KeyboardResponse = 0x55;
                KeyboardReadResponse = TRUE;
                break;
            }

            /* Disable keyboard */
            case 0xAD:
            {
                // TODO: Not implemented
                break;
            }

            /* Enable keyboard */
            case 0xAE:
            {
                // TODO: Not implemented
                break;
            }

            /* Read controller output port */
            case 0xD0:
            {
                // TODO: Not implemented
                break;
            }

            /* CPU Reset */
            case 0xF0:
            case 0xF2:
            case 0xF4:
            case 0xF6:
            case 0xF8:
            case 0xFA:
            case 0xFC:
            case 0xFE:
            {
                /* Stop the simulation */
                VdmRunning = FALSE;
                break;
            }
        }
    }
    else if (Port == PS2_DATA_PORT)
    {
        /* Check if the controller is waiting for a response */
        if (KeyboardWriteResponse)
        {
            KeyboardWriteResponse = FALSE;

            /* Check which command it was */
            switch (KeyboardResponse)
            {
                /* Write configuration byte */
                case 0x60:
                {
                    KeyboardConfig = Data;
                    break;
                }

                /* Write controller output */
                case 0xD1:
                {
                    /* Check if bit 0 is unset */
                    if (!(Data & (1 << 0)))
                    {
                        /* CPU disabled - end simulation */
                        VdmRunning = FALSE;
                    }

                    /* Update the A20 line setting */
                    EmulatorSetA20(Data & (1 << 1));

                    break;
                }
            
                case 0xD2:
                {
                    /* Push the data byte to the keyboard queue */
                    KeyboardQueuePush(Data);
                    break;
                }

                case 0xD3:
                {
                    // TODO: Mouse support
                    break;
                }

                case 0xD4:
                {
                    // TODO: Mouse support
                    break;
                }
            }

            return;
        }

        // TODO: Implement PS/2 device commands
    }
}

VOID GenerateKeyboardInterrupts(VOID)
{
    if (KeyboardQueuePop(&KeyboardData))
    {
        /* IRQ 1 */
        PicInterruptRequest(1);
    }
}

DWORD WINAPI InputThreadProc(LPVOID Parameter)
{
    INT i;
    HANDLE ConsoleInput = (HANDLE)Parameter;
    INPUT_RECORD InputRecord;
    DWORD Count;

    while (VdmRunning)
    {
        /* Wait for an input record */
        if (!ReadConsoleInput(ConsoleInput, &InputRecord, 1, &Count))
        {
            DWORD LastError = GetLastError();
            DPRINT1("Error reading console input (0x%p, %lu) - Error %lu\n", ConsoleInput, Count, LastError);
            return LastError;
        }

        ASSERT(Count != 0);

        /* Check the event type */
        switch (InputRecord.EventType)
        {
            case KEY_EVENT:
            {
                BYTE ScanCode = (BYTE)InputRecord.Event.KeyEvent.wVirtualScanCode;

                /* If this is a key release, set the highest bit in the scan code */
                if (!InputRecord.Event.KeyEvent.bKeyDown) ScanCode |= 0x80;

                /* Push the scan code onto the keyboard queue */
                for (i = 0; i < InputRecord.Event.KeyEvent.wRepeatCount; i++)
                {
                    KeyboardQueuePush(ScanCode);
                }

                break;
            }

            case MOUSE_EVENT:
            {
                // TODO: NOT IMPLEMENTED
                UNIMPLEMENTED;
                break;
            }

            default:
            {
                /* Ignored */
                break;
            }
        }
    }

    return 0;
}

BOOLEAN PS2Initialize(HANDLE ConsoleInput)
{
    /* Create the mutex */
    QueueMutex = CreateMutex(NULL, FALSE, NULL);

    /* Start the input thread */
    InputThread = CreateThread(NULL, 0, &InputThreadProc, ConsoleInput, 0, NULL);

    // if (InputThread == NULL) return FALSE;

    /* Register the I/O Ports */
    RegisterIoPort(PS2_CONTROL_PORT, PS2ReadPort, PS2WritePort);
    RegisterIoPort(PS2_DATA_PORT   , PS2ReadPort, PS2WritePort);

    return TRUE;
}

VOID PS2Cleanup(VOID)
{
    /* Close the input thread handle */
    if (InputThread != NULL) CloseHandle(InputThread);
    InputThread = NULL;

    CloseHandle(QueueMutex);
}

/* EOF */