Snake on novation launchpad

Snake.cpp

#include <iostream>
#include <conio.h> 
#include <cstdio>   
#include <windows.h>   
#include <mmsystem.h> 
#include <cmath>
#include <ctime>

//Snake directions
enum {UP, DOWN, LEFT, RIGHT};

//Easy way to convert between binary and int
union Message{ unsigned long word; char data[4];};
Message message;

//Switch buffer of launchpad
void SwitchBuffer();

//Set the led specified by cell green
void SetLedOn(int cell);

//Set the led specified by cell, with a color
void SetLedOn(int color, int cell);

//Set the led specified by cell off
void SetLedOff(int cell);

//Find empty space in the grid
int FindEmptySpace(int cell);

//Move a cell, and prevent it from going out of grid
int Move(int cell, int dirCode);

//Move the snake
void MoveSnake();

int points = 0;
int snakeLength = 2;
int snakeDir;

int snakeCells[64];
int foodCell;
int snakeOldCell[64];
bool gameover = false;

int flag;
HMIDIOUT device;  

using namespace std;

int main()
{
    srand((unsigned)time(0));

    flag = midiOutOpen(&device, 1, 0, 0, CALLBACK_NULL);
    if (flag != MMSYSERR_NOERROR) {
        cout << "Error opening MIDI Output.\n";
        return 1;
    }

    cout << "Snake, how long can you become? Use WASD to move, and press q to quit.\nPlease press enter to start.\n";
    cin.get();

    snakeCells[0] = 4;
    snakeDir = DOWN;
    foodCell = FindEmptySpace(rand() % 64);

    bool shiftDir = false;
    int pos = -1;

    SwitchBuffer();

    while(1)
    {
        if(_kbhit())
        {
            char key = _getch();
            if(key == 'q')
                break;
            else if(key == 's')
                snakeDir = DOWN;
            else if(key == 'w')
                snakeDir = UP;
            else if(key == 'a')
                snakeDir = LEFT;
            else if(key == 'd')
                snakeDir = RIGHT;
        }
        if(!gameover)
        {
            MoveSnake();

            SetLedOn(63, foodCell);

            SwitchBuffer();

            Sleep(150);
        }
        else
        {
            if(!shiftDir)
                ++pos;
            else
                --pos;

            SetLedOn(62, pos);

            if(!shiftDir && pos % 8 == 7)
            {
                pos += 9;
                shiftDir = true;
            }
            else if(shiftDir && pos % 8 == 0)
            {
                pos += 7;
                shiftDir = false;
            }

            SwitchBuffer();

            Sleep(20);
        }
    }

    message.data[0] = (char)0xB0;
    message.data[1] = (char)0x00;
    message.data[2] = (char)0x00;

    flag = midiOutShortMsg(device, message.word);
    if(flag != MMSYSERR_NOERROR) 
    {
        cout << "Warning: MIDI Output is not open.\n";
    }

    midiOutReset(device);
    midiOutClose(device);

    return 0;
}

void SwitchBuffer()
{
    static bool switchBuffer;
    message.data[0] = (char)0xB0;
    message.data[1] = (char)0x00;

    if(!switchBuffer)
    {
        message.data[2] = 0x31;

        switchBuffer = true;
    }
    else
    {
        message.data[2] = 0x34;
        switchBuffer = false;
    }

    flag = midiOutShortMsg(device, message.word);
    if(flag != MMSYSERR_NOERROR) 
    {
        cout << "Warning: MIDI Output is not open.\n";
    }
}

void SetLedOn(int cell)
{
    message.data[0] = (char)0x90;
    message.data[1] = (int)(cell % 8) + (((int)cell / 8) * 16);
    message.data[2] = (char)48;

    flag = midiOutShortMsg(device, message.word);
    if(flag != MMSYSERR_NOERROR) 
    {
        cout << "Warning: MIDI Output is not open.\n";
    }
}

void SetLedOn(int color, int cell)
{
    message.data[0] = (char)0x90;
    message.data[1] = (int)(cell % 8) + (((int)cell / 8) * 16);
    message.data[2] = (char)color & (char)0x73;

    flag = midiOutShortMsg(device, message.word);
    if(flag != MMSYSERR_NOERROR) 
    {
        cout << "Warning: MIDI Output is not open.\n";
    }
}

void SetLedOff(int cell)
{
    message.data[0] = (char)0x90;
    message.data[1] = (int)(cell % 8) + (((int)cell / 8) * 16);
    message.data[2] = 0;

    flag = midiOutShortMsg(device, message.word);
    if(flag != MMSYSERR_NOERROR) 
    {
        cout << "Warning: MIDI Output is not open.\n";
    }
}

int FindEmptySpace(int cell)
{
    for(int i = 0;i < snakeLength;++i)
    {
        if(snakeCells[i] == cell)
        {
            return FindEmptySpace(rand() % 64);
        }
    }

    return cell;
}

void MoveSnake()
{
    int oldCell = snakeCells[0];
    snakeCells[0] = Move(snakeCells[0], snakeDir);
    snakeOldCell[0] = oldCell;

    SetLedOn(15, snakeCells[0]);

    //Hide old cells
    if(oldCell != snakeCells[0])
    {
        SetLedOff(oldCell);
    }

    for(int i = 1;i < snakeLength;++i)
    {
        oldCell = snakeCells[i];
        snakeCells[i] = snakeOldCell[i - 1];
        snakeOldCell[i] = oldCell;
        
        //Check for collision with head
        if(snakeCells[0] == snakeCells[i])
        {
            message.data[0] = (char)0xB0;
            message.data[1] = (char)0x00;
            message.data[2] = (char)0x00;

            flag = midiOutShortMsg(device, message.word);
            if(flag != MMSYSERR_NOERROR) 
            {
                cout << "Warning: MIDI Output is not open.\n";
            }

            gameover = true;
            return;
        }

        SetLedOn(snakeCells[i]);

        if(oldCell != snakeCells[i])
        {
            SetLedOff(oldCell);
        }
    }

    //Check for collision with food
    if(snakeCells[0] == foodCell)
    {
        snakeCells[snakeLength] = snakeOldCell[snakeLength - 1];
        snakeOldCell[snakeLength] = snakeOldCell[snakeLength - 1];
        foodCell = FindEmptySpace(rand() % 64);

        ++snakeLength;
        points += 10;
        system("cls");
        cout << "You have " << points << " points." << "\n";
    }
}

int Move(int cell, int dirCode)
{
    int column = cell % 8;
    int row = cell / 8;

    if(dirCode == DOWN)
    {
        if(row + 1 > 7)
            return cell;
        else
            return cell + 8;
    }
    else if(dirCode == UP)
    {
        if(row - 1 < 0)
            return cell;
        else
            return cell - 8;
    }
    else if(dirCode == LEFT)
    {
        if(column - 1 < 0)
            return cell;
        else
            return cell - 1;
    }
    else if(dirCode == RIGHT)
    {
        if(column + 1 > 7)
            return cell;
        else
            return cell + 1;
    }

    return cell;
}