File content as of revision 0:b38330b559d4:

#include "mbed.h"
#include "ledScreen.h"

// screen instance
ledScreen screen;

// controller
AnalogIn xJoy(p20);
AnalogIn yJoy(p19);
DigitalIn Abutton(p22);
DigitalIn Bbutton(p21);

//snake
struct snakeBitPos
{
    signed char x;
    signed char y;
};

// sin lookup table and related functions
unsigned char sinlut[256];

void initSinLut() {
    for (int i=0; i<256; i++)
        sinlut[i] = cos((float)i / 256.0 * (3.14159265 * 2))*127 + 128;
}

inline unsigned char lut_sin(int x) {

    return (x>0)?sinlut[x%256]:sinlut[(-x)%256];
}


// Example frame makes:


//rainbow
void makeFrame1(unsigned char* data) {

    static int time=0;
    time++;
    
    // override data with a intensity gradient test pattern
    for (int x=0; x<3*16; x++) {
        for (int y=0; y<48; y++) {

            int i = (x + y*(16*3)) * 3;  // figure out the memory location

            data[i] = lut_sin((x+y)*255/48+(time/2)%256); //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
            data[i+1] = lut_sin(((x+y)*255/48+(time/2)+ 85)%256); //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
            data[i+2] = lut_sin(((x+y)*255/48+(time/2)+170)%256); //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
        }
    }

}

//cool lines
void makeFrame2(unsigned char* data) {

    static int time=0;
    time++;
    
    // override data with a intensity gradient test pattern
    for (int x=0; x<3*16; x++) {
        for (int y=0; y<16; y++) {

            int i = (x + y*(16*3)) * 3;  // figure out the memory location

            data[i] = lut_sin(x*255/48+(time)%256 + y*16); //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
            data[i+1] = lut_sin(x*255/48+(time)%256 + y*16 + 85); //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
            data[i+2] = lut_sin(x*255/48+(time)%256 + y*16 + 170); //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
        }
    }

}

// static gradients
void makeFrame3(unsigned char* data) {

    static int time=0;
    time++;

    // override data with a intensity gradient test pattern
    for (int x=0; x<3*16; x++) {
        for (int y=0; y<16; y++) {

            int i = (x + y*(16*3)) * 3;  // figure out the memory location

            data[i] = x*256/48; //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
            data[i+1] = 0;  // green
            data[i+2] = y*256/16; //(i/3)%256 ; // blue
        }
    }

}

void makeEmptyFrame(unsigned char* data)
{
   for (int x=0; x<3*16; x++) {
        for (int y=0; y<3*16; y++) {

            int i = (x + y*(16*3)) * 3;  // figure out the memory location

            data[i] = 0; 
            data[i+1] = 0;  
            data[i+2] = 0;
        }
    }

}

void stepSnake(unsigned char* data)
{
    static snakeBitPos dotLoc; // going to be the dot
    static unsigned short length=2;
    static unsigned char dir;
    static snakeBitPos snakeArr[100];
    
    static bool firstCall=true;
    if (firstCall) { snakeArr[0].x=20; snakeArr[0].y=20; firstCall=false; dotLoc.x=rand()%48; dotLoc.y=rand()%48; }
    static bool gameover=false;
    static short speed_n = 50;
    
    if (!gameover)
    {
        
        static unsigned short time=0;
        time++;
        time = time%(speed_n/2); // smaller constant = higher speed

        
        // updating direction on every invocation
        float xReading = xJoy.read();
        float yReading = yJoy.read();
        
        if (xReading > 0.9 && dir != 1)
            {dir = 0; }
        else if(xReading < 0.3 && dir != 0)
            {dir = 1; }
        else if(yReading > 0.9 && dir != 3)
            {dir = 2; }
        else if(yReading < 0.3 && dir != 2)
            {dir = 3; }
            
            
        // moving the snake forward     
        if (time == 0)
        {
            for (int j=length; j>0; j--)
            {
                snakeArr[j]=snakeArr[j-1];
            }
            switch(dir)
            {
                case(0):
                    (snakeArr[0]).x++;
                break;
                case(1):
                    (snakeArr[0]).x--;
                break;
                case(2):
                    (snakeArr[0]).y++;
                break;
                case(3):
                    (snakeArr[0]).y--;
                break;
            }
            
        // wrapping
        if (snakeArr[0].x==-1) snakeArr[0].x=47;
        if (snakeArr[0].x==48) snakeArr[0].x=0;
        if (snakeArr[0].y==48) snakeArr[0].y=0;
        if (snakeArr[0].y==-1) snakeArr[0].y=47;

        if (snakeArr[0].y==dotLoc.y && snakeArr[0].x==dotLoc.x)
        {
            dotLoc.x = rand()%48;
            dotLoc.y = rand()%48;
            length++;
            speed_n--; if (speed_n<2) speed_n=2;
        }   
       
        // outputting
        int i=0;  
        // killing own tail (no need to zero whole screen)
        i = (snakeArr[length].x+(snakeArr[length].y)*48)*3;
        data[i] = 0;
        data[i+2] = 0;
    
        // new head alone (no need for looping)
        i = (snakeArr[0].x+(snakeArr[0].y)*48)*3;
        
        // if hitting self, game over
        if (data[i]==255) {data[i+1] = 255; gameover=true;}
        
        data[i] = 255;
        data[i+2] = 127;
        
        data[(dotLoc.x+dotLoc.y*48)*3 +2] = 255;
        }
    }
}


void makeFrame33(unsigned char* data) {

    static int time=0;
    time++;

    for (int x=0; x<3*16; x++) {
        for (int y=0; y<48; y++) {

            int i = (x + y*(16*3)) * 3;  // figure out the memory location

            data[i] = x*256/48; //(sin((float)(x+time)/15.0)+1.0)*128 ;   // red
            data[i+1] = 0;  // green
            data[i+2] = y*256/48; //(i/3)%256 ; // blue
        }
    }
}
 
int main()
{

    // framebuffer on client side
    unsigned char imageSource[256*3*3*3] = { 0 };
    
    // prepare sin lookup table (optional)
    initSinLut(); 

    // start the screen output, which will keep outputting the frames that are in its internal buffer (updated via .transformFrame)
    screen.start();

    makeEmptyFrame(imageSource);

    while (1) {
        
        stepSnake(imageSource);  // prepare framebuffer with current frame
        screen.transformFrame(imageSource); // write framebuffer to output framebuffer
        wait_ms(0.5); // slow down the framerate (optional)
    }

}