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/*
   Compiled with MicroCore: 980 bytes. (Not working..)
   Compiled for Attiny85: 956 bytes.
                          5244 bytes with debug.
How to read this code:
1. Don't. It's ugly.
2. When "pin" is referred in code (or text) it's the Atari side of things. The ATtiny's pins are always referred to as PBX. 

*/

#define LEGACY // Uncomment this if your device does not have a ISP header.
//#define ALT_DETECT

#define DEBUG

// Timings.
#define switchTime 250000
#define saveTime 2000000
#define bootWait 4000 // Wait for computer to stabilize, 3-4s seems ok.
#define pulseThreshold 50000
#define SELECT_PORT PORTB
//#define SELECT_PORT DDRB

#define SAVE_LOCATION 0x1830  //6192

#include <util/delay.h>
#include <EEPROM.h>

#ifdef LEGACY
#define buttonPin PB0       // Connected to switch
#define selectPin PB1     // TS5V330 pin 1
#define pulsePin PB2       // VSync
#define serialRX PB3
#define serialTX PB4
#else
#defien serialRX PB0
#define serialTX PB1
#define pulsePin PB2       // VSync
#define selectPin PB3     // TS5V330 pin 1
#define buttonPin PB4       // Connected to switch
#endif

// Now that the pins are set, undefine LEGACY so that the ifdef's around the DEBUG statements are happy
#undef LEGACY

#if defined(DEBUG) 
#include <SoftwareSerial.h>
SoftwareSerial mySerial(serialRX, serialTX); // RX, TX
#endif

unsigned long buttonPressedTime;

byte state;
byte state_changed = 0;
byte tosState;

#ifdef DEBUG
bool done = false;
String buff;
char data;
int i = 0;
#endif

unsigned long pulse = 0;

void setup() {
// IDEA: check if a jumper is placed on the ISP header to enter some kind of other operations mode. 

  // Set state to an invalid value to make sure the read from flash works
  state = 3;

  // Do the hardware setup for the Atari before setting up the serial port.
  state = EEPROM.read(SAVE_LOCATION);
  PORTB |= bit(buttonPin); // Input pullup.
  // Instead of sending +5V to the Atari, let the pullup on pin4 handle the high part.
  bitWrite(SELECT_PORT, selectPin, state);  
  
#if defined (DEBUG) && !defined(LEGACY)
  mySerial.begin(9600);
  mySerial.println("Boot");
#endif

#if defined (DEBUG) && !defined(LEGACY)
  mySerial.print("Reading state from flash: Saved state ");
  mySerial.println(state);
#endif
  
// Instead of sending +5V to the Atari, let the pullup on pin4 handle the high part.
  bitWrite(DDRB, selectPin, state); 

#if defined (DEBUG) && !defined(LEGACY)
  mySerial.print("Waiting for ");
  mySerial.print(bootWait);
  mySerial.println(" milliseconds.");
#endif
  _delay_ms(bootWait);
  state_changed = 0;

#if defined (DEBUG) && !defined(LEGACY)
  mySerial.println("Loop.");
#endif
}




#ifdef DEBUG
void clearBuff() {
  buff = "";
  i = 0;
  mySerial.print("> ");
}



void printHelp() {
  mySerial.println("Help");
  mySerial.println("-----------");
  mySerial.println("b       - Simulate button press.");
  mySerial.println("p       - Print information.");
  mySerial.println("q       - Quit prompt.");
  mySerial.println("s <num> - Set pulse threashold.");

}
#endif

void toggle_state(void)
{
  if (state == 0)
  {
    state = 1;
  }
  else
  {
    state = 0;
  }
  state_changed = 1;
}

void loop() {

  byte save_now = 0;
  /*
     Detection..
  */
  pulse = 0;
#ifdef ALT_DETECT
  while ( pulse < 10000 ) // 10000 since sometimes you'd get 14 from getPulse();
    pulse = getPulse();
#else

// disable the pulse detection.
#ifdef foo

  // Check for pulsePin going high.  This is to allow for Atari ST program control over the video mode
  while ( ! pulse )
    pulse = pulseIn(pulsePin, HIGH, 1000000L);
#endif

  if ( 0 != pulse )
  { 
    if (pulse < pulseThreshold)
    {
       //mySerial.println("Pulse detected, but below pulse threshold");
       //mySerial.print("Pulse: ");
       //mySerial.println(pulse);
    }
    else
    {
#if defined (DEBUG) && !defined(LEGACY)
      mySerial.println("Pulse detected, and above pulse threshold");
      mySerial.print("Pulse: ");
      mySerial.println(pulse);
#endif
      save_now = 1;
      toggle_state();
    }

  }

  #endif

  // Check for button press.  This is to allow for manual user control over the video mode
  // Short press (> 0.25s and < 2.0s) change mode
  // Long press (>= 2.0s) save mode

  if ( !bitRead(PINB, buttonPin) ) 
  {
    buttonPressedTime = micros();
    while ( ! bitRead(PINB, buttonPin)); // Ugly debounce
    if ( micros() > saveTime  + buttonPressedTime ) 
    {
#if defined (DEBUG) && !defined(LEGACY)
      mySerial.println("Long Button Press");
#endif
      save_now = 1;
    } 
    else if ( micros() > buttonPressedTime + switchTime ) 
    {
#if defined (DEBUG) && !defined(LEGACY)
      mySerial.println("Short Button Press");
#endif
    // Toggle the state
    save_now = 1;
    toggle_state();
    }
  }

  // Check to see if the state should be saved due to a long button press
  if ( 1 == save_now )
  {
 #if defined (DEBUG) && !defined(LEGACY)
      mySerial.println("Save");
      mySerial.print("Value: ");
      mySerial.println(state);
#endif
      save_now = 0;
      EEPROM.write(SAVE_LOCATION, state);
  }

  // If the state has changed, update the state of the selectPin
  if ( 1 == state_changed ) 
  {
#if defined (DEBUG) && !defined(LEGACY)
    //mySerial.println("State change");
    //mySerial.print("New state: ");
    //mySerial.println(state);
#endif
    bitWrite(SELECT_PORT, selectPin, state);
    // Reset the state_changed flag.
    state_changed = 0;
    _delay_ms(1000); // Wait for computer to change video modes
  }
   
}

unsigned long getPulse() {
  pulse = bitRead(PINB, pulsePin);
  while ( bitRead(PINB, pulsePin) == pulse);
  unsigned long pstart = micros();
  while ( bitRead(PINB, pulsePin) != pulse);
  return ( micros() - pstart);
}