/*
   NeoPixel data receiver

   connect the output of a neopixel stripe to D11 of an Arduino Nano

   This program will receive data transported in the last bit and display it as text

   21.11.2021 chris_

*/
// compiler flags changed to O3 ( maximum speed ) line 23-28 in
// ~/tools/Arduino/arduino-1.8.5/hardware/arduino/avr$
// avr-objdump -D -S MCNET_NeoPixelReceiver.ino.elf > dump.txt


// PB3 is D11 on Arduino Nano
#define INPUTPIN (1<<PB3) //
#define PINVALUE (PINB&INPUTPIN)
#define PINLOW (PINVALUE==0)
#define PINHIGH (!PINLOW)

void setup()
{
  Serial.begin(115200);
}

#define BUFFERLENGTH 256+1 // must be 256
uint8_t Buffer[BUFFERLENGTH] = {0};

void recordSignal()
{

  uint8_t n = 0;
  uint8_t *pointer;

  pointer = Buffer;
  
  cli();

  while (PINLOW); // wait for the pin

  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 

  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 
  *pointer++ = PINB; 

  sei();
}


uint8_t BitLengthPointer=0;

float getBitLength()
{
  static uint8_t state=0;
  float hCounter=0,lCounter=0;
  while((Buffer[BitLengthPointer++]& (1 << PB3))==0);
  while((Buffer[BitLengthPointer++]& (1 << PB3))!=0) hCounter++;
  //while((Buffer[BitLengthPointer++]& (1 << PB3))==0) lCounter++;
  return hCounter;
}

boolean getBit()
{
  uint8_t n = 0;

  recordSignal();
  float sum=0;
  for(n=0;n<10;n++)
  {
    float len=getBitLength();
    sum+=len;
    delay(1);
  }
  uint8_t val;
  if(sum>=16)val=1;
  else val=0;
  return val;  
}

uint8_t ReceivedByte=0;

boolean receiveBits(boolean inputBit)
{
  static uint8_t state=0;
  static uint8_t val=0;
  boolean okFlag=false;
  static uint8_t counter=0;
  switch(state)
  {
    // wait for start bit
    case 0:
    {
      counter=0;
      val=0;
      if(inputBit!=0) state=1;
    }break;
    // receive bytes;
    case 1:
    {
      val|=inputBit<<counter;
      counter++;
      if(counter==8) state=2;
    }break;
    case 2:
    {
      ReceivedByte=val;
      okFlag=true;
      state=0;
    }break;
  }
  return okFlag;
}

void loop()
{
  
  uint8_t n = 0;

  recordSignal();

  uint8_t val=getBit();
  //Serial.print (val);Serial.print(" ");
  if(receiveBits(val))
  {
    //Serial.print("==>");Serial.write(ReceivedByte);Serial.print(" - ");Serial.println(ReceivedByte);
    Serial.write(ReceivedByte);
  }

  delay(10);
}