/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.
 
  This example code is in the public domain.
 */
 

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
}

int LED0 = 0x01;
int LED1 = 0x02;
int LED2 = 0x04;
int LED3 = 0x08;

int PWM_BASE = 15;

void channel_set (int duration, int leds, int pwm)
{
  for (int i = 0; i < duration; i+=PWM_BASE) {
    digitalWrite (10, leds & LED0);
    digitalWrite (11, leds & LED1);
    digitalWrite (12, leds & LED2);
    digitalWrite (13, leds & LED3);
    if ((pwm > PWM_BASE) || (pwm == 0)) {
      delay (PWM_BASE);
      continue;
    }
    delay (PWM_BASE-pwm);
    digitalWrite (10, 0); 
    digitalWrite (11, 0);
    digitalWrite (12, 0);
    digitalWrite (13, 0);
    delay (PWM_BASE-(PWM_BASE-pwm));    
  }
}

void run_left(int num, int f, int pwm)
{
  int i = 1;
  
  while (num) {
    channel_set (f, LED3, pwm);
    channel_set (f, LED2, pwm);
    channel_set (f, LED1, pwm);
    if (i >= num)
      break;
    channel_set (f, LED0, pwm);
    i++;
  }
}

void run_right(int num, int f, int pwm)
{
  int i = 1;
 
  while (num) {
    channel_set (f, LED0, pwm);
    channel_set (f, LED1, pwm);
    channel_set (f, LED2, pwm);
    if (i >= num)
      break;
    channel_set (f, LED3, pwm);
    i++;
  }
}

void red_white (int num, int f, int pwm)
{
  for (int i=0; i<num; i++)
  {
    channel_set (f, LED0|LED2, pwm);
    channel_set (f, 0, pwm);
  }
  for (int i=0; i<num; i++)
  {
    channel_set (f, LED1|LED3, pwm);
    channel_set (f, 0, pwm);
  }
  for (int i=0; i<num; i++)
  {
    channel_set (f, LED1, pwm);
    channel_set (f, LED3, pwm);
  }
  for (int i=0; i<num; i++)
  {
    channel_set (f, LED0, pwm);
    channel_set (f, LED2, pwm);
  }  
}

void lr_speedup (int num, int pwm)
{
  int f_start = 100;
  int i = 0;
  do {
    run_right (num-i, f_start, pwm);
    run_left (num-i, f_start, pwm);
    i++;
    f_start += (5 * i);
  } while (i < num);
}

void flash (int num, int on, int off, int pwm)
{
  for (int i=0; i<num; i++)
  {
    channel_set (on, LED0|LED2, pwm);    
    channel_set (off, 0, pwm);
    channel_set (on, LED1|LED3, pwm);
    channel_set (off, 0, pwm);
  }
}

void dimmer (int f)
{ 
  for (int i = PWM_BASE; i > 0; i--)
    channel_set (f*(i/4), LED0|LED1|LED2|LED3, i);
  
  channel_set (f*20, LED0|LED1|LED2|LED3, 0);
  
  for (int i = 1; i <= PWM_BASE; i++)
    channel_set (f*(i/4), LED0|LED1|LED2|LED3, i);  
}

// the loop routine runs over and over again forever:
void loop() {
  dimmer (250);
  red_white (3, 400, PWM_BASE-1);
  flash (10, 200, 80, PWM_BASE-1);  
  lr_speedup (4, PWM_BASE-1);
}