#include <Bounce.h>  // import debounce library

#define encoder0PinA 2  // encoder pin A on pin 2
#define encoder0PinB 3  // encoder pin B on pin 3
#define button 4  // shaft button on pin 4
#define RED 5  // red LED on proto shield on pin 5

volatile unsigned int encoder0Pos = 0;  // scratchpad within ints
volatile unsigned int x = 0;  // delay loop counter

boolean ledValue = LOW;  // LED on/off flag

// Instantiate a Bounce object with a 5 millisecond debounce time
Bounce bouncer = Bounce(button, 5);  

void setup() 
{
  Serial.begin (9600);
  delay(1000);

  pinMode(encoder0PinA, INPUT);
  digitalWrite(encoder0PinA, HIGH);
  pinMode(encoder0PinB, INPUT);
  digitalWrite(encoder0PinB, HIGH);
  pinMode(button, INPUT);
  digitalWrite(button, HIGH);
  pinMode(RED,OUTPUT);

  // encoder pin on interrupt 0 (pin 2)
  attachInterrupt(0, doEncoderA, CHANGE);

  // encoder pin on interrupt 1 (pin 3)
  attachInterrupt(1, doEncoderB, CHANGE);
}

void loop()
{ 
  if (bouncer.update())
  {
    if ( bouncer.read() == HIGH)
    {
      if ( ledValue == LOW ) 
      {
        ledValue = HIGH;
      } 
      else 
      {
        ledValue = LOW;
      }
      digitalWrite(RED,ledValue);
    }
  }
}

void doEncoderA()
{
  // detach interrupts to not interrupt the interrupts
  detachInterrupt(0);
  detachInterrupt(1);

  // a quick and dirty delay to let things settle
  // as delay() doesnt work within interrupts
  for(x=0; x<100; x++)
  {
    asm("nop\n");
  }

  // look for a low-to-high on channel A
  if (digitalRead(encoder0PinA) == HIGH) 
  { 
    // check channel B to see which way encoder is turning
    if (digitalRead(encoder0PinB) == LOW) 
    {  
      encoder0Pos = encoder0Pos + 1;  // CW
    } 
    else 
    {
      encoder0Pos = encoder0Pos - 1;  // CCW
    }
  }

  else   // must be a high-to-low edge on channel A                                       
  { 
    // check channel B to see which way encoder is turning  
    if (digitalRead(encoder0PinB) == HIGH) 
    {   
      encoder0Pos = encoder0Pos + 1;  // CW
    } 
    else 
    {
      encoder0Pos = encoder0Pos - 1;  // CCW
    }
  }
  // use for debugging - remember to comment out
  Serial.println (encoder0Pos, DEC);          

  // reattach interrupts
  attachInterrupt(1, doEncoderB, CHANGE);
  attachInterrupt(0, doEncoderA, CHANGE);
}

void doEncoderB()
{
  // detach interrupts to not interrupt the interrupts
  detachInterrupt(1);
  detachInterrupt(0);

  // a quick and dirty delay to let things settle
  // as delay() doesnt work within interrupts
  for(x=0; x<100; x++)
  {
    asm("nop\n");
  }

  // look for a low-to-high on channel B
  if (digitalRead(encoder0PinB) == HIGH) 
  {   
    // check channel A to see which way encoder is turning
    if (digitalRead(encoder0PinA) == HIGH) 
    {
      encoder0Pos = encoder0Pos + 1;         // CW
    } 
    else 
    {
      encoder0Pos = encoder0Pos - 1;         // CCW
    }
  }
  // Look for a high-to-low on channel B
  else 
  { 
    // check channel B to see which way encoder is turning  
    if (digitalRead(encoder0PinA) == LOW) 
    {
      encoder0Pos = encoder0Pos + 1;          // CW
    } 
    else 
    {
      encoder0Pos = encoder0Pos - 1;          // CCW
    }
  }
  // use for debugging - remember to comment out
  Serial.println (encoder0Pos, DEC);          

  // reattach interrupts
  attachInterrupt(0, doEncoderA, CHANGE);
  attachInterrupt(1, doEncoderB, CHANGE);
}