/* ATmega328P 20MHz */
/* Fuses (E:FF, H:D9, L:F7) */

#define F_CPU 20000000L

#include <avr/io.h>
#include <util/delay.h>  
#include <avr/interrupt.h>
#include <avr/eeprom.h>
#include <avr/wdt.h>
#include "config.h"



volatile uint8_t 
polarization_h, polarization_v, polarization_count, line_pair, i, mode, page, page_flash, keyboard_state, frames_per_keyboard_read, frames_per_keyboard_read_target=5, 
tb_objects, tb_objects_order, tb_ao_position_h, tb_ao_position_v, tb_ao_size_v, tb_ao_frequency, tb_ao_frequency_change_flag, tb_ao_frames_count, tb_ao_frames_per_upper_part, tb_ao_frames_target, tb_ao_position, tb_ao_on_flag, tb_ao_gap, tb_ao_size_v_minus_gap, tb_ao_size_v_plus_gap, tb_di_position_v, tb_di_size_v, tb_di_period, tb_di_period_change_flag, tb_di_position, tb_di_on_flag, tb_di_break, tb_di_gap, 
sbs_objects, sbs_objects_order, sbs_ao_position_h, sbs_ao_position_v, sbs_ao_size_h, sbs_ao_frequency, sbs_ao_frequency_change_flag, sbs_ao_frames_count, sbs_ao_frames_per_left_part, sbs_ao_frames_target, sbs_ao_position, sbs_ao_on_flag, sbs_ao_gap, sbs_di_position_h, sbs_di_size_h, sbs_di_period, sbs_di_period_change_flag, sbs_di_position, sbs_di_on_flag, sbs_di_break, sbs_ao_left_edge, sbs_ao_right_edge, sbs_di_left_edge, sbs_di_right_edge, sbs_line_beginning,
ffr_objects, ffr_objects_order, ffr_fr_position, ffr_fr_visible, ffr_fr_period, ffr_fr_on_flag, ffr_fr_period_change_flag, ffr_fr_v_values_change_flag, ffr_sr_position, ffr_sr_visible, ffr_sr_period, ffr_sr_on_flag, ffr_sr_period_change_flag, ffr_sr_v_values_change_flag, 
frames_per_line_count_change_check;
volatile uint8_t 
rendered_line[320];
volatile int8_t 
tb_di_offset, sbs_di_offset;
volatile uint16_t 
line_count, j, frames_to_settings_save, 
tb_ao_size_h, tb_ao_left_edge, tb_ao_right_edge, tb_di_left_edge, tb_di_right_edge, tb_di_position_h, tb_di_size_h, tb_di_frames_count, tb_di_frames_per_upper_part, tb_di_frames_target, tb_di_left_edge, tb_di_right_edge, 
sbs_ao_size_v, sbs_di_position_v, sbs_di_size_v, sbs_di_frames_count, sbs_di_frames_per_left_part, sbs_di_frames_target, sbs_di_gap,
ffr_gap, ffr_fr_frames_count, ffr_fr_frames_per_visible_part, ffr_fr_frames_target, ffr_fr_position_h, ffr_fr_position_v, ffr_fr_size_h, ffr_fr_size_v, ffr_sr_frames_count, ffr_sr_frames_per_visible_part, ffr_sr_frames_target, ffr_sr_position_h, ffr_sr_position_v, ffr_sr_size_h, ffr_sr_size_v,
number_of_lines_in_previous_frame;
volatile int16_t 
temp_tb_di_size_v, temp_sbs_di_size_h, temp_sbs_di_size_v;




void turn_off_watchdog(void) __attribute__((naked)) __attribute__((section(".init3")));
void turn_off_watchdog(void) {
  MCUSR = 0; // clear Watchdog System Reset Flag, so MCU can start after watchdog system reset
  wdt_reset(); // reset watchdog
  WDTCSR |= (1<<WDCE) | (1<<WDE); // enable change of WDE and prescaler bits
  WDTCSR = (1<<WDE) | (1<<WDP2); //watchdog system reset after 0.25s
}




uint8_t detect_sync_polarity(void) { // detect polarization of synchronization pulses

  wdt_reset(); // reset watchdog to make sure that device won't restart

  /* Every microsecond check voltage level at Hsync input (PB2, INT0). If most of the time low level appears at Hsync input, Hsync pulse has high level and vice versa. */
  polarization_count = 127;
  for(i = 0; i < 255; i++) {
    if(SYNC_INPUT_PORT_IN & (1 << HSYNC_INPUT)) polarization_count++;
    else polarization_count--;
    if(polarization_count==0) {polarization_h = 1; break;}
    if(polarization_count==255) {polarization_h = 0; break;}
    _delay_us(1);
  }

  if(!( (polarization_count == 0) || (polarization_count == 255) )) return 0; // if detecting Hsync pulse polarity took too long, stop pulse polarity detection process

  TCNT1 = 0;

  if(polarization_h) {
    while(!(SYNC_INPUT_PORT_IN & (1 << HSYNC_INPUT))) if(TCNT1 == 3) return 0; // if positive Hsync pulse won't appear within 150us, stop pulse polarity detection process
  }

  else {
    while(SYNC_INPUT_PORT_IN & (1 << HSYNC_INPUT)) if(TCNT1 == 3) return 0; // if negative Hsync pulse won't appear within 150us, stop pulse polarity detection process
  }


  /* Every microsecond check voltage level at Vsync input (PB3, INT1). If most of the time low level apears at Vsync input, Vsync pulse has high level and vice versa. */
  polarization_count = 127;
  for(i = 1; i < 255; i++) {
    if(SYNC_INPUT_PORT_IN & (1 << VSYNC_INPUT)) polarization_count++;
    else polarization_count--;
    if(polarization_count==0) {polarization_v = 1; break;}
    if(polarization_count==255) {polarization_v = 0; break;}
    _delay_us(250);
  }

  if(!( (polarization_count == 0) || (polarization_count == 255) )) return 0; // if detecting Vsync pulse polarity took too long, stop pulse polarity detection process

  TCNT1 = 0;

  if(polarization_v) {
    while(!(SYNC_INPUT_PORT_IN & (1 << VSYNC_INPUT))) if(TCNT1 == 660) return 0; // if positive Vsync pulse won't appear within 33ms, stop pulse polarity detection process
  }

  else {
    while(SYNC_INPUT_PORT_IN & (1 << VSYNC_INPUT)) if(TCNT1 == 660) return 0; // if negative Vsync pulse won't appear within 33ms, stop pulse polarity detection process
  }

  wdt_reset(); // reset watchdog to make sure that device won't restart

  return 1;

}




int main(void) {


  /* Initialize I/O pins */

  MUX_OUTPUT_DDR |= (1 << MUX_OUTPUT);

  NO_SIGNAL_LED_DDR |= (1 << NO_SIGNAL_LED);
  MODE_LED_DDR |= (1 << MODE_LED_UP) | (1 << MODE_LED_DOWN);
  PAGE_LED_DDR |= (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT);

  KEYBOARD_PULL_UP |= (1 << PAGE_KEY) | (1 << SHIFT_KEY) | (1 << LEFT_KEY) | (1 << DOWN_KEY) | (1 << UP_KEY) | (1 << RIGHT_KEY);

  MODE_KEY_PULL_UP |= (1 << MODE_KEY);


  TCCR1B |= (1 << CS12) | (1 << CS10); // 16-bit Timer/Counter1 prescaler to 1024

  NO_SIGNAL_LED_PORT_OUT |= (1 << NO_SIGNAL_LED); // light NO_SIGNAL_LED for the duration of detecting synchronization pulse polarity
  
  while(!detect_sync_polarity()); // wait for for synchronization pulses to appear and be detected

  NO_SIGNAL_LED_PORT_OUT &= ~(1 << NO_SIGNAL_LED); // make NO_SIGNAL_LED dark

  if(polarization_h) EICRA |= (1 << ISC01) | (1 << ISC00); // Hsync pulse has positive polarization, rising edge of INT0 generates an interrupt
  else {EICRA |= (1 << ISC01); EICRA &= ~(1 << ISC00);} // Hsync pulse has negative polarization, falling edge of INT0 generates an interrupt
  if(polarization_v) EICRA |= (1 << ISC11) | (1 << ISC10); // Vsync pulse has positive polarization, rising edge of INT1 generates an interrupt
  else {EICRA |= (1 << ISC11); EICRA &= ~(1 << ISC10);} // Vsync pulse has negative polarization, falling edge of INT1 generates an interrupt

  TCCR1B &= ~(1 << CS12); // 16-bit Timer/Counter1 prescaler to 1
  TCCR0A |= (1 << WGM01); // 8-bit Timer/Counter0 CTC mode
  TCCR0B |= (1 << CS00); // 8-bit Timer/Counter0 prescaler to 1


  /* Read previous state of device from EEPROM. If value is outside of given setting range (for example after uploading program to flash memory), load default settings. */

  tb_ao_frequency = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_FREQUENCY);
  if(tb_ao_frequency > MAX_TB_AO_FREQUENCY) tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY;
  tb_ao_frames_per_upper_part = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_FRAMES_PER_UPPER_PART);
  if(tb_ao_frames_per_upper_part > MAX_TB_AO_FRAMES_PER_UPPER_PART) tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART;
  tb_ao_on_flag = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_ON_FLAG);
  if(tb_ao_on_flag > MAX_TB_AO_ON_FLAG) tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG;
  tb_ao_gap = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_GAP);
  if(tb_ao_gap > MAX_TB_AO_GAP) tb_ao_gap = DEFAULT_TB_AO_GAP;

  tb_ao_position_h = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_POSITION_H);
  if((tb_ao_position_h<MIN_TB_AO_POSITION_H) || (tb_ao_position_h>MAX_TB_AO_POSITION_H)) tb_ao_position_h = DEFAULT_TB_AO_POSITION_H;
  tb_ao_position_v = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_POSITION_V);
  if(tb_ao_position_v > MAX_TB_AO_POSITION_V) tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
  tb_ao_size_h = eeprom_read_word((uint16_t*)ADDRESS_TB_AO_SIZE_H);
  if((tb_ao_size_h<MIN_TB_AO_SIZE_H) || (tb_ao_size_h>MAX_TB_AO_SIZE_H)) tb_ao_size_h = DEFAULT_TB_AO_SIZE_H;
  tb_ao_size_v = eeprom_read_byte((uint8_t*)ADDRESS_TB_AO_SIZE_V);
  if((tb_ao_size_v<MIN_TB_AO_SIZE_V) || (tb_ao_size_v>MAX_TB_AO_SIZE_V)) tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;

  tb_di_period = eeprom_read_byte((uint8_t*)ADDRESS_TB_DI_PERIOD);
  if(tb_di_period > MAX_TB_DI_PERIOD) tb_di_period = DEFAULT_TB_DI_PERIOD;
  tb_di_frames_per_upper_part = eeprom_read_word((uint16_t*)ADDRESS_TB_DI_FRAMES_PER_UPPER_PART);
  if(tb_di_frames_per_upper_part > MAX_TB_DI_FRAMES_PER_UPPER_PART) tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART;
  tb_di_on_flag = eeprom_read_byte((uint8_t*)ADDRESS_TB_DI_ON_FLAG);
  if(tb_di_on_flag > MAX_TB_DI_ON_FLAG) tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG;
  tb_di_offset = eeprom_read_byte((uint8_t*)ADDRESS_TB_DI_OFFSET);
  if((tb_di_offset<MIN_TB_DI_OFFSET) || (tb_di_offset>MAX_TB_DI_OFFSET)) tb_di_offset = DEFAULT_TB_DI_OFFSET;
  tb_di_break = eeprom_read_byte((uint8_t*)ADDRESS_TB_DI_BREAK);
  if(tb_di_break > MAX_TB_DI_BREAK) tb_di_break = DEFAULT_TB_DI_BREAK;

  tb_di_position_h = eeprom_read_word((uint16_t*)ADDRESS_TB_DI_POSITION_H);
  if(tb_di_position_h>MAX_TB_DI_POSITION_H) tb_di_position_h = DEFAULT_TB_DI_POSITION_H;
  tb_di_position_v = eeprom_read_byte((uint8_t*)ADDRESS_TB_DI_POSITION_V);
  if(tb_di_position_v > MAX_TB_DI_POSITION_V) tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
  tb_di_size_h = eeprom_read_word((uint16_t*)ADDRESS_TB_DI_SIZE_H);
  if((tb_di_size_h<MIN_TB_DI_SIZE_H) || (tb_di_size_h>MAX_TB_DI_SIZE_H)) tb_di_size_h = DEFAULT_TB_DI_SIZE_H;
  tb_di_size_v = eeprom_read_byte((uint8_t*)ADDRESS_TB_DI_SIZE_V);
  if( (tb_di_size_v < MIN_TB_DI_SIZE_V) || (tb_di_size_v > MAX_TB_DI_SIZE_V)) tb_di_size_v = DEFAULT_TB_DI_SIZE_V;


  sbs_ao_frequency = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_FREQUENCY);
  if(sbs_ao_frequency > MAX_SBS_AO_FREQUENCY) sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY;
  sbs_ao_frames_per_left_part = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_FRAMES_PER_LEFT_PART);
  if(sbs_ao_frames_per_left_part > MAX_SBS_AO_FRAMES_PER_LEFT_PART) sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART;
  sbs_ao_on_flag = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_ON_FLAG);
  if(sbs_ao_on_flag > MAX_SBS_AO_ON_FLAG) sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG;
  sbs_ao_gap = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_GAP);
  if(sbs_ao_gap > MAX_SBS_AO_GAP) sbs_ao_gap = DEFAULT_SBS_AO_GAP;

  sbs_ao_position_h = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_H);
  if((sbs_ao_position_h<MIN_SBS_AO_POSITION_H) || (sbs_ao_position_h>MAX_SBS_AO_POSITION_H)) sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H;
  sbs_ao_position_v = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_V);
  if(sbs_ao_position_v > MAX_SBS_AO_POSITION_V) sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
  sbs_ao_right_edge = eeprom_read_byte((uint8_t*)ADDRESS_SBS_AO_RIGHT_EDGE);
  if((sbs_ao_right_edge<MIN_SBS_AO_RIGHT_EDGE) || (sbs_ao_right_edge>MAX_SBS_RIGHT_EDGE)) sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE;
  sbs_ao_size_v = eeprom_read_word((uint16_t*)ADDRESS_SBS_AO_SIZE_V);
  if((sbs_ao_size_v<MIN_SBS_AO_SIZE_V) || (sbs_ao_size_v>MAX_SBS_AO_SIZE_V)) sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;

  sbs_di_period = eeprom_read_byte((uint8_t*)ADDRESS_SBS_DI_PERIOD);
  if(sbs_di_period > MAX_SBS_DI_PERIOD) sbs_di_period = DEFAULT_SBS_DI_PERIOD;
  sbs_di_frames_per_left_part = eeprom_read_word((uint16_t*)ADDRESS_SBS_DI_FRAMES_PER_LEFT_PART);
  if(sbs_di_frames_per_left_part > MAX_SBS_DI_FRAMES_PER_LEFT_PART) sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART;
  sbs_di_on_flag = eeprom_read_byte((uint8_t*)ADDRESS_SBS_DI_ON_FLAG);
  if(sbs_di_on_flag > MAX_SBS_DI_ON_FLAG) sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG;
  sbs_di_offset = eeprom_read_byte((uint8_t*)ADDRESS_SBS_DI_OFFSET);
  if((sbs_di_offset<MIN_SBS_DI_OFFSET) || (sbs_di_offset>MAX_SBS_DI_OFFSET)) sbs_di_offset = DEFAULT_SBS_DI_OFFSET;
  sbs_di_break = eeprom_read_byte((uint8_t*)ADDRESS_SBS_DI_BREAK);
  if(sbs_di_break > MAX_SBS_DI_BREAK) sbs_di_break = DEFAULT_SBS_DI_BREAK;

  sbs_di_position_h = eeprom_read_byte((uint8_t*)ADDRESS_SBS_DI_POSITION_H);
  if((sbs_di_position_h<MIN_SBS_DI_POSITION_H) || (sbs_di_position_h>MAX_SBS_DI_POSITION_H)) sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H;
  sbs_di_position_v = eeprom_read_word((uint16_t*)ADDRESS_SBS_DI_POSITION_V);
  if(sbs_di_position_v > MAX_SBS_DI_POSITION_V) sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
  sbs_di_size_h = eeprom_read_byte((uint8_t*)ADDRESS_SBS_DI_SIZE_H);
  if((sbs_di_size_h<MIN_SBS_DI_SIZE_H) || (sbs_di_size_h>MAX_SBS_DI_SIZE_H)) sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H;
  sbs_di_size_v = eeprom_read_word((uint16_t*)ADDRESS_SBS_DI_SIZE_V);
  if((sbs_di_size_v < MIN_SBS_DI_SIZE_V) || (sbs_di_size_v > MAX_SBS_DI_SIZE_V)) sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;


  ffr_fr_position = eeprom_read_byte((uint8_t*)ADDRESS_FFR_FR_POSITION);
  if(ffr_fr_position > MAX_FFR_FR_POSITION) ffr_fr_position = DEFAULT_FFR_FR_POSITION;
  ffr_fr_period = eeprom_read_byte((uint8_t*)ADDRESS_FFR_FR_PERIOD);
  if(ffr_fr_period > MAX_FFR_FR_PERIOD) ffr_fr_period = DEFAULT_FFR_FR_PERIOD;
  ffr_fr_frames_per_visible_part = eeprom_read_word((uint16_t*)ADDRESS_FFR_FR_FRAMES_PER_VISIBLE_PART);
  if(ffr_fr_frames_per_visible_part > MAX_FFR_FR_FRAMES_PER_VISIBLE_PART) ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART;
  ffr_fr_on_flag = eeprom_read_byte((uint8_t*)ADDRESS_FFR_FR_ON_FLAG);
  if(ffr_fr_on_flag > MAX_FFR_FR_ON_FLAG) ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG;

  ffr_fr_position_h = eeprom_read_word((uint16_t*)ADDRESS_FFR_FR_POSITION_H);
  if((ffr_fr_position_h<MIN_FFR_FR_POSITION_H) || (ffr_fr_position_h>MAX_FFR_FR_POSITION_H)) ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H;
  ffr_fr_position_v = eeprom_read_word((uint16_t*)ADDRESS_FFR_FR_POSITION_V);
  if(ffr_fr_position_v > MAX_FFR_FR_POSITION_V) ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
  ffr_fr_size_h = eeprom_read_word((uint16_t*)ADDRESS_FFR_FR_SIZE_H);
  if((ffr_fr_size_h<MIN_FFR_FR_SIZE_H) || (ffr_fr_size_h>MAX_FFR_FR_SIZE_H)) ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H;
  ffr_fr_size_v = eeprom_read_word((uint16_t*)ADDRESS_FFR_FR_SIZE_V);
  if( (ffr_fr_size_v < MIN_FFR_FR_SIZE_V) || (ffr_fr_size_v > MAX_FFR_FR_SIZE_V)) ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;

  ffr_sr_position = eeprom_read_byte((uint8_t*)ADDRESS_FFR_SR_POSITION);
  if(ffr_sr_position > MAX_FFR_SR_POSITION) ffr_sr_position = DEFAULT_FFR_SR_POSITION;
  ffr_sr_period = eeprom_read_byte((uint8_t*)ADDRESS_FFR_SR_PERIOD);
  if(ffr_sr_period > MAX_FFR_SR_PERIOD) ffr_sr_period = DEFAULT_FFR_SR_PERIOD;
  ffr_sr_frames_per_visible_part = eeprom_read_word((uint16_t*)ADDRESS_FFR_SR_FRAMES_PER_VISIBLE_PART);
  if(ffr_sr_frames_per_visible_part > MAX_FFR_SR_FRAMES_PER_VISIBLE_PART) ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART;
  ffr_sr_on_flag = eeprom_read_byte((uint8_t*)ADDRESS_FFR_SR_ON_FLAG);
  if(ffr_sr_on_flag > MAX_FFR_SR_ON_FLAG) ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG;

  ffr_sr_position_h = eeprom_read_word((uint16_t*)ADDRESS_FFR_SR_POSITION_H);
  if((ffr_sr_position_h<MIN_FFR_SR_POSITION_H) || (ffr_sr_position_h>MAX_FFR_SR_POSITION_H)) ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H;
  ffr_sr_position_v = eeprom_read_word((uint16_t*)ADDRESS_FFR_SR_POSITION_V);
  if(ffr_sr_position_v > MAX_FFR_SR_POSITION_V) ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
  ffr_sr_size_h = eeprom_read_word((uint16_t*)ADDRESS_FFR_SR_SIZE_H);
  if((ffr_sr_size_h<MIN_FFR_SR_SIZE_H) || (ffr_sr_size_h>MAX_FFR_SR_SIZE_H)) ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H;
  ffr_sr_size_v = eeprom_read_word((uint16_t*)ADDRESS_FFR_SR_SIZE_V);
  if( (ffr_sr_size_v < MIN_FFR_SR_SIZE_V) || (ffr_sr_size_v > MAX_FFR_SR_SIZE_V)) ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;



  EIMSK |= (1 << INT1) | (1 << INT0); // enable Hsync and Vsync interrupts

  sei(); // global interrupt enable


  while (1) {

  }


}




/* Vsync interrupt. Change of settings and rendering is done here. */
ISR(INT1_vect) {

  TIMSK1 &= ~( (1 << OCIE1B) | (1 << OCIE1A) ); // disable 16-bit Timer/Counter1 compare match interrupts

  wdt_reset(); // reset watchdog to make sure that device won't restart

  /* Every 10 frames check if number of lines in frame did not change (change of resolution). If so, restart MCU with Watchdog System Reset (detection of sync pulse polarity is done at MCU start-up). */
  frames_per_line_count_change_check++;
  if(frames_per_line_count_change_check > 10) {
    if(number_of_lines_in_previous_frame > 80) {
      if( (line_count < number_of_lines_in_previous_frame - 5) || (line_count > number_of_lines_in_previous_frame + 5) ) {
        wdt_reset();
        WDTCSR |= (1<<WDCE) | (1<<WDE); // enable change of WDE and prescaler bits
        WDTCSR &= ~(1<<WDP2); //watchdog system reset after 16ms
        while(1);
      }
    }
    frames_per_line_count_change_check = 0;
    number_of_lines_in_previous_frame = line_count;
  }
  
  line_count = 0; // set line_count to 0 (line_count is used to indicate current line of picture, both during actuall drawing of picture overlay and overlay rendering)


  switch(mode) { 


    /* --- VIDEO PASS-THROUGH --- */
    case 0: 

      /* Read keyboard. */
      if(frames_per_keyboard_read == frames_per_keyboard_read_target) { // read keyboard every frames_per_keyboard_read_target
  
        frames_per_keyboard_read_target = 5; // by default every 5 frames (changes when button is pressed)
        frames_per_keyboard_read = 0;

        if( !(MODE_KEY_PORT_IN &= (1 << MODE_KEY)) ) { // if MODE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) { mode++; if(mode >= 4) mode = 0; frames_per_keyboard_read_target = 10; } // and PAGE_KEY is not, change mode to next one
          else { // if MODE_KEY and PAGE_KEY are both pressed, set default settings
            mode = 0;
            page = 5;
            tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY;
            tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART;
            tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG;
            tb_ao_gap = DEFAULT_TB_AO_GAP;
            tb_ao_position_h = DEFAULT_TB_AO_POSITION_H;
            tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
            tb_ao_size_h = DEFAULT_TB_AO_SIZE_H;
            tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
            tb_di_period = DEFAULT_TB_DI_PERIOD;
            tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART;
            tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG;
            tb_di_offset = DEFAULT_TB_DI_OFFSET;
            tb_di_break = DEFAULT_TB_DI_BREAK;
            tb_di_position_h = DEFAULT_TB_DI_POSITION_H;
            tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
            tb_di_size_h = DEFAULT_TB_DI_SIZE_H;
            tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FREQUENCY, tb_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FRAMES_PER_UPPER_PART, tb_ao_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_ON_FLAG, tb_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_GAP, tb_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_H, tb_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_V, tb_ao_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_AO_SIZE_H, tb_ao_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_SIZE_V, tb_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_PERIOD, tb_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_FRAMES_PER_UPPER_PART, tb_di_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_ON_FLAG, tb_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_OFFSET, tb_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_BREAK, tb_di_break);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_POSITION_H, tb_di_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_POSITION_V, tb_di_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_SIZE_H, tb_di_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_SIZE_V, tb_di_size_v);
            sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY;
            sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART;
            sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG;
            sbs_ao_gap = DEFAULT_SBS_AO_GAP;
            sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H;
            sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
            sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE;
            sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
            sbs_di_period = DEFAULT_SBS_DI_PERIOD;
            sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART;
            sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG;
            sbs_di_offset = DEFAULT_SBS_DI_OFFSET;
            sbs_di_break = DEFAULT_SBS_DI_BREAK;
            sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H;
            sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
            sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H;
            sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FREQUENCY, sbs_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FRAMES_PER_LEFT_PART, sbs_ao_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_ON_FLAG, sbs_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_GAP, sbs_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_H, sbs_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_V, sbs_ao_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_RIGHT_EDGE, sbs_ao_right_edge);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_AO_SIZE_V, sbs_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_PERIOD, sbs_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_FRAMES_PER_LEFT_PART, sbs_di_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_ON_FLAG, sbs_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_OFFSET, sbs_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_BREAK, sbs_di_break);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_POSITION_H, sbs_di_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_POSITION_V, sbs_di_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_SIZE_H, sbs_di_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_SIZE_V, sbs_di_size_v);
            ffr_fr_position = DEFAULT_FFR_FR_POSITION;
            ffr_fr_period = DEFAULT_FFR_FR_PERIOD;
            ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART;
            ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG;
            ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H;
            ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
            ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H;
            ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
            ffr_sr_position = DEFAULT_FFR_SR_POSITION;
            ffr_sr_period = DEFAULT_FFR_SR_PERIOD;
            ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART;
            ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG;
            ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H;
            ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
            ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H;
            ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_POSITION, ffr_fr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_PERIOD, ffr_fr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_FRAMES_PER_VISIBLE_PART, ffr_fr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_ON_FLAG, ffr_fr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_H, ffr_fr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_V, ffr_fr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_H, ffr_fr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_V, ffr_fr_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_POSITION, ffr_sr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_PERIOD, ffr_sr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_FRAMES_PER_VISIBLE_PART, ffr_sr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_ON_FLAG, ffr_sr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_H, ffr_sr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_V, ffr_sr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_H, ffr_sr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_V, ffr_sr_size_v);
            frames_per_keyboard_read_target = 20;
          }
        }
        if( !(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) ) { // if PAGE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) { page++; if(page >= 6) page = 0; } // and SHIFT_KEY is not, change page to next one
          else { page--; if(page > 240) page = 5; } // if PAGE_KEY and SHIFT_KEY are both pressed, change page to previous one
          frames_per_keyboard_read_target = 10; // 10 frames till next keyboard read
        }

      }
      frames_per_keyboard_read++;  

    break;


    /* --- TOP - BOTTOM --- */
    case 1:


      /* Read keyboard. */
      if(frames_per_keyboard_read == frames_per_keyboard_read_target) { // read keyboard every frames_per_keyboard_read_target
  
        frames_per_keyboard_read_target = 5; // by default every 5 frames (changes when button is pressed)
        frames_per_keyboard_read = 0;

        if( !(MODE_KEY_PORT_IN &= (1 << MODE_KEY)) ) { // if MODE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) { mode++; if(mode >= 4) mode = 0; frames_per_keyboard_read_target = 10; } // and PAGE_KEY is not, change mode to next one
          else { // if MODE_KEY and PAGE_KEY are both pressed, set default settings
            mode = 0;
            page = 5;
            tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY;
            tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART;
            tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG;
            tb_ao_gap = DEFAULT_TB_AO_GAP;
            tb_ao_position_h = DEFAULT_TB_AO_POSITION_H;
            tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
            tb_ao_size_h = DEFAULT_TB_AO_SIZE_H;
            tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
            tb_di_period = DEFAULT_TB_DI_PERIOD;
            tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART;
            tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG;
            tb_di_offset = DEFAULT_TB_DI_OFFSET;
            tb_di_break = DEFAULT_TB_DI_BREAK;
            tb_di_position_h = DEFAULT_TB_DI_POSITION_H;
            tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
            tb_di_size_h = DEFAULT_TB_DI_SIZE_H;
            tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FREQUENCY, tb_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FRAMES_PER_UPPER_PART, tb_ao_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_ON_FLAG, tb_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_GAP, tb_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_H, tb_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_V, tb_ao_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_AO_SIZE_H, tb_ao_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_SIZE_V, tb_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_PERIOD, tb_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_FRAMES_PER_UPPER_PART, tb_di_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_ON_FLAG, tb_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_OFFSET, tb_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_BREAK, tb_di_break);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_POSITION_H, tb_di_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_POSITION_V, tb_di_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_SIZE_H, tb_di_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_SIZE_V, tb_di_size_v);
            sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY;
            sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART;
            sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG;
            sbs_ao_gap = DEFAULT_SBS_AO_GAP;
            sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H;
            sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
            sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE;
            sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
            sbs_di_period = DEFAULT_SBS_DI_PERIOD;
            sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART;
            sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG;
            sbs_di_offset = DEFAULT_SBS_DI_OFFSET;
            sbs_di_break = DEFAULT_SBS_DI_BREAK;
            sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H;
            sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
            sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H;
            sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FREQUENCY, sbs_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FRAMES_PER_LEFT_PART, sbs_ao_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_ON_FLAG, sbs_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_GAP, sbs_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_H, sbs_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_V, sbs_ao_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_RIGHT_EDGE, sbs_ao_right_edge);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_AO_SIZE_V, sbs_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_PERIOD, sbs_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_FRAMES_PER_LEFT_PART, sbs_di_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_ON_FLAG, sbs_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_OFFSET, sbs_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_BREAK, sbs_di_break);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_POSITION_H, sbs_di_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_POSITION_V, sbs_di_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_SIZE_H, sbs_di_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_SIZE_V, sbs_di_size_v);
            ffr_fr_position = DEFAULT_FFR_FR_POSITION;
            ffr_fr_period = DEFAULT_FFR_FR_PERIOD;
            ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART;
            ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG;
            ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H;
            ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
            ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H;
            ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
            ffr_sr_position = DEFAULT_FFR_SR_POSITION;
            ffr_sr_period = DEFAULT_FFR_SR_PERIOD;
            ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART;
            ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG;
            ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H;
            ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
            ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H;
            ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_POSITION, ffr_fr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_PERIOD, ffr_fr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_FRAMES_PER_VISIBLE_PART, ffr_fr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_ON_FLAG, ffr_fr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_H, ffr_fr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_V, ffr_fr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_H, ffr_fr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_V, ffr_fr_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_POSITION, ffr_sr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_PERIOD, ffr_sr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_FRAMES_PER_VISIBLE_PART, ffr_sr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_ON_FLAG, ffr_sr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_H, ffr_sr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_V, ffr_sr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_H, ffr_sr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_V, ffr_sr_size_v);
            frames_per_keyboard_read_target = 20;
          }
        }
        if( !(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) ) { // if PAGE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) { page++; if(page >= 6) page = 0; } // and SHIFT_KEY is not, change page to next one
          else { page--; if(page > 240) page = 5; } // if PAGE_KEY and SHIFT_KEY are both pressed, change page to previous one
          frames_per_keyboard_read_target = 10; // 10 frames till next keyboard read
        }

        /* Store information about other keys in keyboard_state */
        if( !(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) ) keyboard_state |= (1 << 4);
        else keyboard_state &= ~(1 << 4);
        if( !(KEYBOARD_PORT_IN &= (1 << LEFT_KEY)) ) keyboard_state |= (1 << 3);
        else keyboard_state &= ~(1 << 3);
        if( !(KEYBOARD_PORT_IN &= (1 << UP_KEY)) ) keyboard_state |= (1 << 2);
        else keyboard_state &= ~(1 << 2);
        if( !(KEYBOARD_PORT_IN &= (1 << DOWN_KEY)) ) keyboard_state |= (1 << 1);
        else keyboard_state &= ~(1 << 1);
        if( !(KEYBOARD_PORT_IN &= (1 << RIGHT_KEY)) ) keyboard_state |= (1 << 0);
        else keyboard_state &= ~(1 << 0);

        switch(page) {
  
          /* Alternating Occlusions Settings */
          case 0: 
            switch(keyboard_state) {

              /* Without the SHIFT_KEY pressed. */
              case 0x01:
                if(tb_ao_frequency==0) tb_ao_frames_per_upper_part = tb_ao_frames_per_upper_part + 2; 
                else tb_ao_frames_per_upper_part++; 
                if(tb_ao_frames_per_upper_part > tb_ao_frames_target) tb_ao_frames_per_upper_part = tb_ao_frames_target;
                frames_per_keyboard_read_target = 10;
              break;
              case 0x02: tb_ao_frequency--; if(tb_ao_frequency > 240) tb_ao_frequency = 0; tb_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x04: tb_ao_frequency++; if(tb_ao_frequency > MAX_TB_AO_FREQUENCY) tb_ao_frequency = MAX_TB_AO_FREQUENCY; tb_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x08: 
                if(tb_ao_frequency==0) tb_ao_frames_per_upper_part = tb_ao_frames_per_upper_part - 2;
                else tb_ao_frames_per_upper_part--; 
                if(tb_ao_frames_per_upper_part > 240) tb_ao_frames_per_upper_part = 0;
                frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: tb_ao_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x12: tb_ao_gap--; if(tb_ao_gap > 240) tb_ao_gap = 0; frames_per_keyboard_read_target = 10; break;
              case 0x14: tb_ao_gap++; if(tb_ao_gap > MAX_TB_AO_GAP) tb_ao_gap = MAX_TB_AO_GAP; frames_per_keyboard_read_target = 10; break;
              case 0x18: tb_ao_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: tb_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x06: tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; tb_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; frames_per_keyboard_read_target = 10; break;
              case 0x16: tb_ao_gap = DEFAULT_TB_AO_GAP; frames_per_keyboard_read_target = 10; break;
              case 0x0f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x1f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1;
                tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
                tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1;
                tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
                tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Alternating Occlusions Position */
          case 1: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: tb_ao_position_h++; if(tb_ao_position_h > MAX_TB_AO_POSITION_H) tb_ao_position_h = MAX_TB_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x02: tb_ao_position_v++; if(tb_ao_position_v > MAX_TB_AO_POSITION_V) tb_ao_position_v = MAX_TB_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x04: tb_ao_position_v--; if(tb_ao_position_v > 240) tb_ao_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x08: tb_ao_position_h--; if(tb_ao_position_h < MIN_TB_AO_POSITION_H) tb_ao_position_h = MIN_TB_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: tb_ao_position_h = tb_ao_position_h + 10; if(tb_ao_position_h > MAX_TB_AO_POSITION_H) tb_ao_position_h = MAX_TB_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x12: tb_ao_position_v = tb_ao_position_v + 5; if(tb_ao_position_v > MAX_TB_AO_POSITION_V) tb_ao_position_v = MAX_TB_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x14: tb_ao_position_v = tb_ao_position_v - 5; if(tb_ao_position_v > 240) tb_ao_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x18: 
                tb_ao_position_h = tb_ao_position_h - 10; 
                if( (tb_ao_position_h < MIN_TB_AO_POSITION_H) || (tb_ao_position_h > 240) ) tb_ao_position_h = MIN_TB_AO_POSITION_H; frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: tb_ao_position_v = DEFAULT_TB_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: tb_ao_position_v = DEFAULT_TB_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1;
                tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
                tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1;
                tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
                tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Alternating Occlusions Size */
          case 2: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: tb_ao_size_h++; if(tb_ao_size_h > MAX_TB_AO_SIZE_H) tb_ao_size_h = MAX_TB_AO_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x02: tb_ao_size_v++; if(tb_ao_size_v > MAX_TB_AO_SIZE_V) tb_ao_size_v = MAX_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x04: 
                tb_ao_size_v--; if(tb_ao_size_v < MIN_TB_AO_SIZE_V) tb_ao_size_v = MIN_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; 
                if(tb_ao_size_v < (tb_di_position_v+tb_di_size_v) ) { tb_di_size_v--; if(tb_di_size_v < MIN_TB_DI_SIZE_V) { tb_di_size_v = MIN_TB_DI_SIZE_V; tb_di_position_v--; } }
              break;
              case 0x08: tb_ao_size_h--; if(tb_ao_size_h < MIN_TB_AO_SIZE_H) tb_ao_size_h = MIN_TB_AO_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: tb_ao_size_h = tb_ao_size_h + 10; if(tb_ao_size_h > MAX_TB_AO_SIZE_H) tb_ao_size_h = MAX_TB_AO_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x12: tb_ao_size_v = tb_ao_size_v + 5; if(tb_ao_size_v > MAX_TB_AO_SIZE_V) tb_ao_size_v = MAX_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x14: 
                tb_ao_size_v = tb_ao_size_v - 5; if(tb_ao_size_v < MIN_TB_AO_SIZE_V) tb_ao_size_v = MIN_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; 
                if(tb_ao_size_v < (tb_di_position_v+tb_di_size_v) ) { tb_di_size_v=tb_di_size_v-5; if(tb_di_size_v < MIN_TB_DI_SIZE_V) { tb_di_size_v = MIN_TB_DI_SIZE_V; tb_di_position_v=tb_di_position_v-5; } } 
              break;
              case 0x18: tb_ao_size_h = tb_ao_size_h - 10; if(tb_ao_size_h < MIN_TB_AO_SIZE_H) tb_ao_size_h = MIN_TB_AO_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: tb_ao_size_v = DEFAULT_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: tb_ao_size_v = DEFAULT_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1;
                tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
                tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1;
                tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
                tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Dichoptic Settings  */
          case 3: 
            switch(keyboard_state) {

              /* Without the SHIFT_KEY pressed. */
              case 0x01:
                if(tb_di_period==0) tb_di_frames_per_upper_part = tb_di_frames_per_upper_part + 40; 
                else if(tb_di_period==5) tb_di_frames_per_upper_part = tb_di_frames_per_upper_part + 10;
                else tb_di_frames_per_upper_part = tb_di_frames_per_upper_part + 20; 
                if(tb_di_frames_per_upper_part > tb_di_frames_target) tb_di_frames_per_upper_part = tb_di_frames_target;
                frames_per_keyboard_read_target = 10;
              break;
              case 0x02: 
              tb_di_period--; if(tb_di_period > 240) tb_di_period = 0; tb_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x04: 
              tb_di_period++; if(tb_di_period > MAX_TB_DI_PERIOD) tb_di_period = MAX_TB_DI_PERIOD; tb_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: 
                if(tb_di_period==0) tb_di_frames_per_upper_part = tb_di_frames_per_upper_part - 40;
                else if(tb_di_period==5) tb_di_frames_per_upper_part = tb_di_frames_per_upper_part - 10; 
                else tb_di_frames_per_upper_part = tb_di_frames_per_upper_part - 20; 
                if(tb_di_frames_per_upper_part > 65000) tb_di_frames_per_upper_part = 0;
                frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: tb_di_offset++; if(tb_di_offset > MAX_TB_DI_OFFSET) tb_di_offset = MAX_TB_DI_OFFSET; frames_per_keyboard_read_target = 10; break;
              case 0x12: 
                if(tb_di_period==0) {
                  tb_di_break = tb_di_break + 40; if(tb_di_break > 160) tb_di_break = 0; break; }
                else {
                  tb_di_break = tb_di_break + 20; if(tb_di_break > 80) tb_di_break = 0; break; }
                frames_per_keyboard_read_target = 10;
              case 0x14: tb_di_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x18: tb_di_offset--; if(tb_di_offset < MIN_TB_DI_OFFSET) tb_di_offset = MIN_TB_DI_OFFSET; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: tb_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x06: tb_di_period = DEFAULT_TB_DI_PERIOD; tb_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: tb_di_offset = DEFAULT_TB_DI_OFFSET; frames_per_keyboard_read_target = 10; break;
              case 0x16: tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; frames_per_keyboard_read_target = 10; break;
              case 0x0f: 
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x1f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1;
                tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
                tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1;
                tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
                tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Dichoptic Position */
          case 4: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: tb_di_position_h++; if( (tb_di_position_h  + tb_di_size_h) > tb_ao_size_h ) tb_di_position_h--; frames_per_keyboard_read_target = 10; break;
              case 0x02: tb_di_position_v++; if( (tb_di_position_v + tb_di_size_v) > tb_ao_size_v_minus_gap ) tb_di_position_v--; frames_per_keyboard_read_target = 10; break;
              case 0x04: tb_di_position_v--; if(tb_di_position_v > 240) tb_di_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x08: tb_di_position_h--; if(tb_di_position_h > 65000) tb_di_position_h = MIN_TB_DI_POSITION_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: tb_di_position_h = tb_di_position_h + 10; if( (tb_di_position_h  + tb_di_size_h) > tb_ao_size_h ) tb_di_position_h = tb_ao_size_h - tb_di_size_h; frames_per_keyboard_read_target = 10; break;
              case 0x12: 
                tb_di_position_v = tb_di_position_v + 5; 
                if( (tb_di_position_v + tb_di_size_v) > tb_ao_size_v_minus_gap ) tb_di_position_v = tb_ao_size_v_minus_gap - tb_di_size_v; frames_per_keyboard_read_target = 10; 
              break;
              case 0x14: tb_di_position_v = tb_di_position_v - 5; if(tb_di_position_v > 240) tb_di_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x18: 
                tb_di_position_h = tb_di_position_h - 10; 
                if(tb_di_position_h > 65000) tb_di_position_h = MIN_TB_DI_POSITION_H; frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: tb_di_position_h = DEFAULT_TB_DI_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: tb_di_position_v = DEFAULT_TB_DI_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: tb_di_position_h = DEFAULT_TB_DI_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: tb_di_position_v = DEFAULT_TB_DI_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1;
                tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
                tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1;
                tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
                tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Dichoptic Size */
          case 5: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: tb_di_size_h++; if( (tb_di_position_h  + tb_di_size_h) > tb_ao_size_h ) tb_di_size_h--; frames_per_keyboard_read_target = 10; break;
              case 0x02: tb_di_size_v++; if( (tb_di_position_v + tb_di_size_v) > tb_ao_size_v_minus_gap ) tb_di_size_v--; frames_per_keyboard_read_target = 10; break;
              case 0x04: tb_di_size_v--; if(tb_di_size_v < MIN_TB_DI_SIZE_V) tb_di_size_v = MIN_TB_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x08: tb_di_size_h--; if(tb_di_size_h < MIN_TB_DI_SIZE_H) tb_di_size_h = MIN_TB_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: tb_di_size_h = tb_di_size_h + 10; if( (tb_di_position_h  + tb_di_size_h) > tb_ao_size_h ) tb_di_size_h = tb_ao_size_h - tb_di_position_h; frames_per_keyboard_read_target = 10; break;
              case 0x12: tb_di_size_v = tb_di_size_v + 5; if( (tb_di_position_v + tb_di_size_v) > tb_ao_size_v_minus_gap ) tb_di_size_v = tb_ao_size_v_minus_gap - tb_di_position_v; frames_per_keyboard_read_target = 10; break;
              case 0x14: tb_di_size_v = tb_di_size_v - 5; if(tb_di_size_v < MIN_TB_DI_SIZE_V) tb_di_size_v = MIN_TB_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x18: tb_di_size_h = tb_di_size_h - 10; if( (tb_di_size_h < MIN_TB_DI_SIZE_H) || (tb_di_size_h > 65000) ) tb_di_size_h = MIN_TB_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: tb_di_size_h = DEFAULT_TB_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: tb_di_size_v = DEFAULT_TB_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: tb_di_size_h = DEFAULT_TB_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: tb_di_size_v = DEFAULT_TB_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART; tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY; 
                tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG; tb_ao_gap = DEFAULT_TB_AO_GAP; tb_ao_frequency_change_flag = 1;
                tb_ao_position_h = DEFAULT_TB_AO_POSITION_H; tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
                tb_ao_size_h = DEFAULT_TB_AO_SIZE_H; tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
                tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART; tb_di_period = DEFAULT_TB_DI_PERIOD; 
                tb_di_offset = DEFAULT_TB_DI_OFFSET; tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG; tb_di_break = DEFAULT_TB_DI_BREAK; tb_di_period_change_flag = 1;
                tb_di_position_h = DEFAULT_TB_DI_POSITION_H; tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
                tb_di_size_h = DEFAULT_TB_DI_SIZE_H; tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;


        }


        /* Make sure that dihoptic rectangle stays inside alternately occluding rectangle, horizontally.  */
        if( (tb_di_position_h + tb_di_size_h) > tb_ao_size_h ) {
          tb_di_size_h = tb_ao_size_h - tb_di_position_h;  
          if( (tb_di_size_h > 65000) || (tb_di_size_h < MIN_TB_DI_SIZE_H) ) { 
            tb_di_size_h = MIN_TB_DI_SIZE_H;
            if( (tb_di_position_h + tb_di_size_h) > tb_ao_size_h ) tb_di_position_h = tb_ao_size_h - MIN_TB_DI_SIZE_H;     
          } 
        }

        
        /* Make sure that maximum number of lines is not exceeded. */
        if( (tb_ao_position_v + 2*tb_ao_size_v) > 2*MAX_TB_AO_SIZE_V ) tb_ao_size_v = (2*MAX_TB_AO_SIZE_V - tb_ao_position_v)/2;


        tb_ao_size_v_minus_gap = tb_ao_size_v - tb_ao_gap;
        tb_ao_size_v_plus_gap = tb_ao_size_v + tb_ao_gap;

        /* Make sure that dihoptic rectangle stays inside alternately occluding rectangle, vertically.  */
        if( (tb_di_position_v + tb_di_size_v) > tb_ao_size_v_minus_gap ) {
          temp_tb_di_size_v = tb_ao_size_v_minus_gap - tb_di_position_v;  
          tb_di_size_v = temp_tb_di_size_v;
          if(temp_tb_di_size_v < MIN_TB_DI_SIZE_V) { 
            tb_di_size_v = MIN_TB_DI_SIZE_V;
            if( (tb_di_position_v + tb_di_size_v) > tb_ao_size_v_minus_gap ) tb_di_position_v = tb_ao_size_v_minus_gap - MIN_TB_DI_SIZE_V;     
          }
        } 


        /* Set total number of frames in a cycle according to tb_ao_frequency. */
        switch(tb_ao_frequency) { 
          case 0: tb_ao_frames_target=24; break; // 2.5 Hz
          case 1: tb_ao_frames_target=12; break; // 5 Hz
          case 2: tb_ao_frames_target=8; break; // 7.5 Hz
          case 3: tb_ao_frames_target=6; break; // 10 Hz
          case 4: tb_ao_frames_target=5; break; // 12 Hz
          case 5: tb_ao_frames_target=4; break; // 15 Hz
        }
        if(tb_ao_frequency_change_flag==1) { // if change of tb_ao_frequency occurred, set default number of frames during with alternately occluding rectangle occupies upper part of the picture
          switch(tb_ao_frequency) { 
            case 0: tb_ao_frames_per_upper_part=12; break; 
            case 1: tb_ao_frames_per_upper_part=6; break; 
            case 2: tb_ao_frames_per_upper_part=4; break; 
            case 3: tb_ao_frames_per_upper_part=3; break; 
            case 4: tb_ao_frames_per_upper_part=3; break; 
            case 5: tb_ao_frames_per_upper_part=2; break; 
          }
          tb_ao_frequency_change_flag = 0;
        }

        /* Set total number of frames in a cycle according to tb_di_period. */
        switch(tb_di_period) { 
          case 0: tb_di_frames_target=480; break; // 8s
          case 1: tb_di_frames_target=280; break; // 4.67s
          case 2: tb_di_frames_target=200; break; // 3.33s
          case 3: tb_di_frames_target=120; break; // 2s
          case 4: tb_di_frames_target=80; break; // 1.33s
          case 5: tb_di_frames_target=40; break; // 0.67s
        }
        if(tb_di_period_change_flag==1) { // if change of tb_di_period occurred, set default number of frames during with dihoptic rectangle occupies upper part of the picture
          switch(tb_di_period) { 
            case 0: tb_di_frames_per_upper_part=240; break; 
            case 1: tb_di_frames_per_upper_part=140; break; 
            case 2: tb_di_frames_per_upper_part=100; break; 
            case 3: tb_di_frames_per_upper_part=60; break; 
            case 4: tb_di_frames_per_upper_part=40; break; 
            case 5: tb_di_frames_per_upper_part=20; break; 
          }
          tb_di_period_change_flag = 0;
        }

      }
      frames_per_keyboard_read++;


      /* --- Timing and Rendering --- */

      /* Determine where alternately occluding rectangle should appear. */
      tb_ao_frames_count++;
      if(tb_ao_frames_count >= tb_ao_frames_target) tb_ao_frames_count = 0;
      if(tb_ao_frames_count < tb_ao_frames_per_upper_part) tb_ao_position = 1; // up
      else tb_ao_position = 2; // down

      /* Determine where dihoptic rectangle should appear. */
      tb_di_frames_count++;
      if( tb_di_frames_count >= (tb_di_frames_target + 2*tb_di_break) ) tb_di_frames_count = 0;
      if(tb_di_frames_count < tb_di_frames_per_upper_part) tb_di_position = 1; // up
      else if( tb_di_frames_count < (tb_di_frames_per_upper_part + tb_di_break) ) tb_di_position = 0; // not visible during the brake
      else if(tb_di_frames_count < (tb_di_frames_target + tb_di_break) ) tb_di_position = 2; // down
      else tb_di_position = 0;

      /* Calculate where edges of alternately occluding rectangle are. */
      tb_ao_right_edge = tb_ao_position_h + tb_ao_size_h;
      tb_ao_left_edge = tb_ao_position_h;

      /* Calculate where edges of dihoptic rectangle are. */
      if(tb_di_position == 2) tb_di_left_edge = tb_ao_position_h + tb_di_position_h + tb_di_offset;
      else tb_di_left_edge = tb_ao_position_h + tb_di_position_h;
      tb_di_right_edge = tb_di_left_edge + tb_di_size_h;

      /* Make sure that edges of dihoptic rectangle stay inside alternately occluding rectangle (applying tb_di_offset might have move dihoptic rectangle too far). */
      if( (tb_di_left_edge<tb_ao_position_h) || (tb_di_left_edge>65000) ) tb_di_left_edge = tb_ao_position_h;
      if(tb_di_right_edge>tb_ao_right_edge) tb_di_right_edge = tb_ao_right_edge;

      /* Calculate number of lines that separate bottom edge of dihoptic rectangle from line that lies exacatly between alternately occluding rectangles. */
      tb_di_gap = tb_ao_size_v - ( tb_di_position_v + tb_di_size_v);


      /* Determine order in with rectangles will be displayed, while taking into account that some rectangles may not be visible or they may be turned off. */
      tb_objects = ( tb_di_on_flag << 5 ) | ( tb_ao_on_flag << 4 ) | ( tb_di_position << 2 ) | tb_ao_position;

      switch(tb_objects) { 

        case 0x01: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x02: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x05: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x06: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x09: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x0a: tb_objects_order = 0x00; break; // EMPTY, EMPTY

        case 0x11: tb_objects_order = 0x10; break; // AO, EMPTY
        case 0x12: tb_objects_order = 0x01; break; // EMPTY, AO
        case 0x15: tb_objects_order = 0x10; break; // AO, EMPTY
        case 0x16: tb_objects_order = 0x01; break; // EMPTY, AO
        case 0x19: tb_objects_order = 0x10; break; // AO, EMPTY
        case 0x1a: tb_objects_order = 0x01; break; // EMPTY, AO

        case 0x21: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x22: tb_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x25: tb_objects_order = 0x20; break; // DI, EMPTY
        case 0x26: tb_objects_order = 0x20; break; // DI, EMPTY
        case 0x29: tb_objects_order = 0x02; break; // EMPTY, DI
        case 0x2a: tb_objects_order = 0x02; break; // EMPTY, DI

        case 0x31: tb_objects_order = 0x10; break; // AO, EMPTY
        case 0x32: tb_objects_order = 0x01; break; // EMPTY, AO
        case 0x35: tb_objects_order = 0x10; break; // AO, EMPTY
        case 0x36: tb_objects_order = 0x21; break; // DI, AO
        case 0x39: tb_objects_order = 0x12; break; // AO, DI
        case 0x3a: tb_objects_order = 0x01; break; // EMPTY, AO

      }


      /* Determine every rendered line content (which rectangle it contains). */
      switch(tb_objects_order) { 

        case 0x01: 
          for(i = 0; i < tb_ao_position_v; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_ao_size_v_plus_gap; i++) rendered_line[line_count++] = 0;   
          for(i = 0; i < tb_ao_size_v_minus_gap; i++) rendered_line[line_count++] = 1;      
        break;

        case 0x02: 
          for(i = 0; i < tb_ao_position_v; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_ao_size_v; i++) rendered_line[line_count++] = 0;  
          for(i = 0; i < tb_ao_gap; i++) rendered_line[line_count++] = 0; 
          for(i = 0; i < tb_di_position_v; i++) rendered_line[line_count++] = 0; 
          for(i = 0; i < tb_di_size_v; i++) rendered_line[line_count++] = 2; 
        break;

        case 0x10: 
          for(i = 0; i < tb_ao_position_v; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_ao_size_v_minus_gap; i++) rendered_line[line_count++] = 1;   
          for(i = 0; i < tb_ao_size_v_plus_gap; i++) rendered_line[line_count++] = 0;
        break;

        case 0x12: 
          for(i = 0; i < tb_ao_position_v; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_ao_size_v_minus_gap; i++) rendered_line[line_count++] = 1;   
          for(i = 0; i < tb_ao_gap; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_ao_gap; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_di_position_v; i++) rendered_line[line_count++] = 0; 
          for(i = 0; i < tb_di_size_v; i++) rendered_line[line_count++] = 2;
        break;

        case 0x20: 
          for(i = 0; i < tb_ao_position_v; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_di_position_v; i++) rendered_line[line_count++] = 0; 
          for(i = 0; i < tb_di_size_v; i++) rendered_line[line_count++] = 2;  
        break;

        case 0x21: 
          for(i = 0; i < tb_ao_position_v; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_di_position_v; i++) rendered_line[line_count++] = 0; 
          for(i = 0; i < tb_di_size_v; i++) rendered_line[line_count++] = 2;   
          for(i = 0; i < tb_di_gap; i++) rendered_line[line_count++] = 0; 
          for(i = 0; i < tb_ao_gap; i++) rendered_line[line_count++] = 0;
          for(i = 0; i < tb_ao_size_v_minus_gap; i++) rendered_line[line_count++] = 1; 
        break;

      }


    break;


    /* --- SIDE BY SIDE --- */
    case 2:


      /* Read keyboard. */
      if(frames_per_keyboard_read == frames_per_keyboard_read_target) { // read keyboard every frames_per_keyboard_read_target
  
        frames_per_keyboard_read_target = 5; // by default every 5 frames (changes when button is pressed)
        frames_per_keyboard_read = 0;

        if( !(MODE_KEY_PORT_IN &= (1 << MODE_KEY)) ) { // if MODE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) { mode++; if(mode >= 4) mode = 0; frames_per_keyboard_read_target = 10; } // and PAGE_KEY is not, change mode to next one
          else { // if MODE_KEY and PAGE_KEY are both pressed, set default settings
            mode = 0;
            page = 5;
            tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY;
            tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART;
            tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG;
            tb_ao_gap = DEFAULT_TB_AO_GAP;
            tb_ao_position_h = DEFAULT_TB_AO_POSITION_H;
            tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
            tb_ao_size_h = DEFAULT_TB_AO_SIZE_H;
            tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
            tb_di_period = DEFAULT_TB_DI_PERIOD;
            tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART;
            tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG;
            tb_di_offset = DEFAULT_TB_DI_OFFSET;
            tb_di_break = DEFAULT_TB_DI_BREAK;
            tb_di_position_h = DEFAULT_TB_DI_POSITION_H;
            tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
            tb_di_size_h = DEFAULT_TB_DI_SIZE_H;
            tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FREQUENCY, tb_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FRAMES_PER_UPPER_PART, tb_ao_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_ON_FLAG, tb_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_GAP, tb_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_H, tb_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_V, tb_ao_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_AO_SIZE_H, tb_ao_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_SIZE_V, tb_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_PERIOD, tb_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_FRAMES_PER_UPPER_PART, tb_di_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_ON_FLAG, tb_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_OFFSET, tb_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_BREAK, tb_di_break);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_POSITION_H, tb_di_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_POSITION_V, tb_di_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_SIZE_H, tb_di_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_SIZE_V, tb_di_size_v);
            sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY;
            sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART;
            sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG;
            sbs_ao_gap = DEFAULT_SBS_AO_GAP;
            sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H;
            sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
            sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE;
            sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
            sbs_di_period = DEFAULT_SBS_DI_PERIOD;
            sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART;
            sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG;
            sbs_di_offset = DEFAULT_SBS_DI_OFFSET;
            sbs_di_break = DEFAULT_SBS_DI_BREAK;
            sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H;
            sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
            sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H;
            sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FREQUENCY, sbs_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FRAMES_PER_LEFT_PART, sbs_ao_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_ON_FLAG, sbs_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_GAP, sbs_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_H, sbs_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_V, sbs_ao_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_RIGHT_EDGE, sbs_ao_right_edge);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_AO_SIZE_V, sbs_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_PERIOD, sbs_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_FRAMES_PER_LEFT_PART, sbs_di_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_ON_FLAG, sbs_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_OFFSET, sbs_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_BREAK, sbs_di_break);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_POSITION_H, sbs_di_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_POSITION_V, sbs_di_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_SIZE_H, sbs_di_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_SIZE_V, sbs_di_size_v);
            ffr_fr_position = DEFAULT_FFR_FR_POSITION;
            ffr_fr_period = DEFAULT_FFR_FR_PERIOD;
            ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART;
            ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG;
            ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H;
            ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
            ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H;
            ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
            ffr_sr_position = DEFAULT_FFR_SR_POSITION;
            ffr_sr_period = DEFAULT_FFR_SR_PERIOD;
            ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART;
            ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG;
            ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H;
            ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
            ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H;
            ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_POSITION, ffr_fr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_PERIOD, ffr_fr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_FRAMES_PER_VISIBLE_PART, ffr_fr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_ON_FLAG, ffr_fr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_H, ffr_fr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_V, ffr_fr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_H, ffr_fr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_V, ffr_fr_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_POSITION, ffr_sr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_PERIOD, ffr_sr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_FRAMES_PER_VISIBLE_PART, ffr_sr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_ON_FLAG, ffr_sr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_H, ffr_sr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_V, ffr_sr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_H, ffr_sr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_V, ffr_sr_size_v);
            frames_per_keyboard_read_target = 20;
          }
        }
        if( !(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) ) { // if PAGE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) { page++; if(page >= 6) page = 0; } // and SHIFT_KEY is not, change page to next one
          else { page--; if(page > 240) page = 5; } // if PAGE_KEY and SHIFT_KEY are both pressed, change page to previous one
          frames_per_keyboard_read_target = 10; // 10 frames till next keyboard read
        }

        /* Store information about other keys in keyboard_state */
        if( !(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) ) keyboard_state |= (1 << 4);
        else keyboard_state &= ~(1 << 4);
        if( !(KEYBOARD_PORT_IN &= (1 << LEFT_KEY)) ) keyboard_state |= (1 << 3);
        else keyboard_state &= ~(1 << 3);
        if( !(KEYBOARD_PORT_IN &= (1 << UP_KEY)) ) keyboard_state |= (1 << 2);
        else keyboard_state &= ~(1 << 2);
        if( !(KEYBOARD_PORT_IN &= (1 << DOWN_KEY)) ) keyboard_state |= (1 << 1);
        else keyboard_state &= ~(1 << 1);
        if( !(KEYBOARD_PORT_IN &= (1 << RIGHT_KEY)) ) keyboard_state |= (1 << 0);
        else keyboard_state &= ~(1 << 0);

        switch(page) {
  
          /* Alternating Occlusions Settings */
          case 0: 
            switch(keyboard_state) {

              /* Without the SHIFT_KEY pressed. */
              case 0x01:
                if(sbs_ao_frequency==0) sbs_ao_frames_per_left_part = sbs_ao_frames_per_left_part + 2; 
                else sbs_ao_frames_per_left_part++; 
                if(sbs_ao_frames_per_left_part > sbs_ao_frames_target) sbs_ao_frames_per_left_part = sbs_ao_frames_target;
                frames_per_keyboard_read_target = 10;
              break;
              case 0x02: sbs_ao_frequency--; if(sbs_ao_frequency > 240) sbs_ao_frequency = 0; sbs_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x04: sbs_ao_frequency++; if(sbs_ao_frequency > MAX_SBS_AO_FREQUENCY) sbs_ao_frequency = MAX_SBS_AO_FREQUENCY; sbs_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x08: 
                if(sbs_ao_frequency==0) sbs_ao_frames_per_left_part = sbs_ao_frames_per_left_part - 2;
                else sbs_ao_frames_per_left_part--; 
                if(sbs_ao_frames_per_left_part > 240) sbs_ao_frames_per_left_part = 0;
                frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: sbs_ao_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x12: sbs_ao_gap--; if(sbs_ao_gap < MIN_SBS_AO_GAP) sbs_ao_gap = MIN_SBS_AO_GAP; frames_per_keyboard_read_target = 10; break;
              case 0x14: sbs_ao_gap++; if(sbs_ao_gap > MAX_SBS_AO_GAP) sbs_ao_gap = MAX_SBS_AO_GAP; frames_per_keyboard_read_target = 10; break;
              case 0x18: sbs_ao_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: sbs_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x06: sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; sbs_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; frames_per_keyboard_read_target = 10; break;
              case 0x16: sbs_ao_gap = DEFAULT_SBS_AO_GAP; frames_per_keyboard_read_target = 10; break;
              case 0x0f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x1f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1;
                sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
                sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1;
                sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
                sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Alternating Occlusions Position */
          case 1: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: sbs_ao_position_h++; if(sbs_ao_position_h > MAX_SBS_AO_POSITION_H) sbs_ao_position_h = MAX_SBS_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x02: sbs_ao_position_v++; if(sbs_ao_position_v > MAX_SBS_AO_POSITION_V) sbs_ao_position_v = MAX_SBS_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x04: sbs_ao_position_v--; if(sbs_ao_position_v > 240) sbs_ao_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x08: sbs_ao_position_h--; if(sbs_ao_position_h < MIN_SBS_AO_POSITION_H) sbs_ao_position_h = MIN_SBS_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: sbs_ao_position_h = sbs_ao_position_h + 10; if(sbs_ao_position_h > MAX_SBS_AO_POSITION_H) sbs_ao_position_h = MAX_SBS_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x12: sbs_ao_position_v = sbs_ao_position_v + 10; if(sbs_ao_position_v > MAX_SBS_AO_POSITION_V) sbs_ao_position_v = MAX_SBS_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x14: sbs_ao_position_v = sbs_ao_position_v - 10; if(sbs_ao_position_v > 240) sbs_ao_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x18: 
                sbs_ao_position_h = sbs_ao_position_h - 10; 
                if( (sbs_ao_position_h < MIN_SBS_AO_POSITION_H) || (sbs_ao_position_h > 240) ) sbs_ao_position_h = MIN_SBS_AO_POSITION_H; frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1;
                sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
                sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1;
                sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
                sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Alternating Occlusions Size */
          case 2: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: sbs_ao_right_edge++; if(sbs_ao_right_edge > MAX_SBS_RIGHT_EDGE) sbs_ao_right_edge = MAX_SBS_RIGHT_EDGE; frames_per_keyboard_read_target = 10; break;
              case 0x02: sbs_ao_size_v++; if(sbs_ao_size_v > MAX_SBS_AO_SIZE_V) sbs_ao_size_v = MAX_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x04: 
                sbs_ao_size_v--; if(sbs_ao_size_v < MIN_SBS_AO_SIZE_V) sbs_ao_size_v = MIN_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: 
                sbs_ao_right_edge--; if(sbs_ao_right_edge < MIN_SBS_AO_RIGHT_EDGE) sbs_ao_right_edge = MIN_SBS_AO_RIGHT_EDGE; frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: sbs_ao_right_edge = sbs_ao_right_edge + 5; if(sbs_ao_right_edge > MAX_SBS_RIGHT_EDGE) sbs_ao_right_edge = MAX_SBS_RIGHT_EDGE; frames_per_keyboard_read_target = 10; break;
              case 0x12: sbs_ao_size_v = sbs_ao_size_v + 10; if(sbs_ao_size_v > MAX_SBS_AO_SIZE_V) sbs_ao_size_v = MAX_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x14: 
                sbs_ao_size_v = sbs_ao_size_v - 10; if(sbs_ao_size_v < MIN_SBS_AO_SIZE_V) sbs_ao_size_v = MIN_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; 
              break;
              case 0x18: 
                sbs_ao_right_edge = sbs_ao_right_edge - 5; if(sbs_ao_right_edge < MIN_SBS_AO_RIGHT_EDGE) sbs_ao_right_edge = MIN_SBS_AO_RIGHT_EDGE; frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; frames_per_keyboard_read_target = 10; break;
              case 0x06: sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; frames_per_keyboard_read_target = 10; break;
              case 0x16: sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1;
                sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
                sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1;
                sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
                sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Dichoptic Settings  */
          case 3: 
            switch(keyboard_state) {

              /* Without the SHIFT_KEY pressed. */
              case 0x01:
                if(sbs_di_period==0) sbs_di_frames_per_left_part = sbs_di_frames_per_left_part + 40; 
                else if(sbs_di_period==5) sbs_di_frames_per_left_part = sbs_di_frames_per_left_part + 10;
                else sbs_di_frames_per_left_part = sbs_di_frames_per_left_part + 20; 
                if(sbs_di_frames_per_left_part > sbs_di_frames_target) sbs_di_frames_per_left_part = sbs_di_frames_target;
                frames_per_keyboard_read_target = 10;
              break;
              case 0x02: 
              sbs_di_period--; if(sbs_di_period > 240) sbs_di_period = 0; sbs_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x04: 
              sbs_di_period++; if(sbs_di_period > MAX_SBS_DI_PERIOD) sbs_di_period = MAX_SBS_DI_PERIOD; sbs_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: 
                if(sbs_di_period==0) sbs_di_frames_per_left_part = sbs_di_frames_per_left_part - 40;
                else if(sbs_di_period==5) sbs_di_frames_per_left_part = sbs_di_frames_per_left_part - 10; 
                else sbs_di_frames_per_left_part = sbs_di_frames_per_left_part - 20; 
                if(sbs_di_frames_per_left_part > 65000) sbs_di_frames_per_left_part = 0;
                frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: sbs_di_offset++; if(sbs_di_offset > MAX_SBS_DI_OFFSET) sbs_di_offset = MAX_SBS_DI_OFFSET; frames_per_keyboard_read_target = 10; break;
              case 0x12: 
                if(sbs_di_period==0) {
                  sbs_di_break = sbs_di_break + 40; if(sbs_di_break > 160) sbs_di_break = 0; break; }
                else {
                  sbs_di_break = sbs_di_break + 20; if(sbs_di_break > 80) sbs_di_break = 0; break; }
                frames_per_keyboard_read_target = 10;
              case 0x14: sbs_di_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x18: sbs_di_offset--; if(sbs_di_offset < MIN_SBS_DI_OFFSET) sbs_di_offset = MIN_SBS_DI_OFFSET; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: sbs_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x06: sbs_di_period = DEFAULT_SBS_DI_PERIOD; sbs_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: sbs_di_offset = DEFAULT_SBS_DI_OFFSET; frames_per_keyboard_read_target = 10; break;
              case 0x16: sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; frames_per_keyboard_read_target = 10; break;
              case 0x0f: 
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x1f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1;
                sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
                sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1;
                sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
                sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Dichoptic Position */
          case 4: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: sbs_di_position_h++; if( (sbs_di_position_h  + sbs_di_size_h) > (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) ) sbs_di_position_h--; frames_per_keyboard_read_target = 10; break;
              case 0x02: sbs_di_position_v++; if( (sbs_di_position_v + sbs_di_size_v) > sbs_ao_size_v ) sbs_di_position_v--; frames_per_keyboard_read_target = 10; break;
              case 0x04: sbs_di_position_v--; if(sbs_di_position_v > 65000) sbs_di_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x08: sbs_di_position_h--; if(sbs_di_position_h < MIN_SBS_DI_POSITION_H) sbs_di_position_h = MIN_SBS_DI_POSITION_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: 
                sbs_di_position_h = sbs_di_position_h + 10; 
                if( (sbs_di_position_h  + sbs_di_size_h) > (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) ) sbs_di_position_h = (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) - sbs_di_size_h; frames_per_keyboard_read_target = 10; 
              break;
              case 0x12: 
                sbs_di_position_v = sbs_di_position_v + 10; 
                if( (sbs_di_position_v + sbs_di_size_v) > sbs_ao_size_v ) sbs_di_position_v = sbs_ao_size_v - sbs_di_size_v; frames_per_keyboard_read_target = 10; 
              break;
              case 0x14: sbs_di_position_v = sbs_di_position_v - 10; if(sbs_di_position_v > 65000) sbs_di_position_v = 0; frames_per_keyboard_read_target = 10; break;
              case 0x18: 
                sbs_di_position_h = sbs_di_position_h - 10; 
                if( (sbs_di_position_h < MIN_SBS_DI_POSITION_H) || (sbs_di_position_h > 240) ) sbs_di_position_h = MIN_SBS_DI_POSITION_H; frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1;
                sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
                sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1;
                sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
                sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Dichoptic Size */
          case 5: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: sbs_di_size_h++; if( (sbs_di_position_h  + sbs_di_size_h) > (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) ) sbs_di_size_h--; frames_per_keyboard_read_target = 10; break;
              case 0x02: sbs_di_size_v++; if( (sbs_di_position_v + sbs_di_size_v) > sbs_ao_size_v ) sbs_di_size_v--; frames_per_keyboard_read_target = 10; break;
              case 0x04: sbs_di_size_v--; if(sbs_di_size_v < MIN_SBS_DI_SIZE_V) sbs_di_size_v = MIN_SBS_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x08: sbs_di_size_h--; if(sbs_di_size_h < MIN_SBS_DI_SIZE_H) sbs_di_size_h = MIN_SBS_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: 
                sbs_di_size_h = sbs_di_size_h + 10; 
                if( (sbs_di_position_h  + sbs_di_size_h) > (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) ) sbs_di_size_h = (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) - sbs_di_position_h; frames_per_keyboard_read_target = 10; break;
              case 0x12: sbs_di_size_v = sbs_di_size_v + 10; if( (sbs_di_position_v + sbs_di_size_v) > sbs_ao_size_v ) sbs_di_size_v = sbs_ao_size_v - sbs_di_position_v; frames_per_keyboard_read_target = 10; break;
              case 0x14: sbs_di_size_v = sbs_di_size_v - 10; if(sbs_di_size_v < MIN_SBS_DI_SIZE_V) sbs_di_size_v = MIN_SBS_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x18: sbs_di_size_h = sbs_di_size_h - 10; if( (sbs_di_size_h < MIN_SBS_DI_SIZE_H) || (sbs_di_size_h > 240) ) sbs_di_size_h = MIN_SBS_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x19: sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x0f: sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART; sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY; 
                sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG; sbs_ao_gap = DEFAULT_SBS_AO_GAP; sbs_ao_frequency_change_flag = 1;
                sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H; sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
                sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE; sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
                sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART; sbs_di_period = DEFAULT_SBS_DI_PERIOD;
                sbs_di_offset = DEFAULT_SBS_DI_OFFSET; sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG; sbs_di_break = DEFAULT_SBS_DI_BREAK; sbs_di_period_change_flag = 1;
                sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H; sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
                sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H; sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;


        }


        sbs_ao_size_h = sbs_ao_right_edge - sbs_ao_gap;

        /* Make sure that dihoptic rectangle stays inside alternately occluding rectangle, horizontally.  */
        if( (sbs_di_position_h + sbs_di_size_h) > (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) ) {
          temp_sbs_di_size_h = (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) - sbs_di_position_h; 
          sbs_di_size_h = temp_sbs_di_size_h;
          if(temp_sbs_di_size_h < MIN_SBS_DI_SIZE_H) { 
            sbs_di_size_h = MIN_SBS_DI_SIZE_H;
            if( (sbs_di_position_h + sbs_di_size_h) > (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) ) sbs_di_position_h = (sbs_ao_size_h-MIN_SBS_DI_POSITION_H) - sbs_di_size_h;     
          } 
        }

        /* Make sure that dihoptic rectangle stays inside alternately occluding rectangle, vertically.  */
        if( (sbs_di_position_v + sbs_di_size_v) > sbs_ao_size_v) {
          temp_sbs_di_size_v = sbs_ao_size_v - sbs_di_position_v; 
          sbs_di_size_v = temp_sbs_di_size_v;
          if(temp_sbs_di_size_v < MIN_SBS_DI_SIZE_V) { 
            sbs_di_size_v = MIN_SBS_DI_SIZE_V;
            if( (sbs_di_position_v + sbs_di_size_v) > sbs_ao_size_v ) sbs_di_position_v = sbs_ao_size_v - sbs_di_size_v;     
          } 
        }

        /* Make sure that maximum number of lines is not exceeded. */
        if( (sbs_ao_position_v + sbs_ao_size_v) > 274 ) sbs_ao_size_v = 274 - sbs_ao_position_v;      


        /* Set total number of frames in a cycle according to sbs_ao_frequency. */
        switch(sbs_ao_frequency) { 
          case 0: sbs_ao_frames_target=24; break; // 2.5 Hz
          case 1: sbs_ao_frames_target=12; break; // 5 Hz
          case 2: sbs_ao_frames_target=8; break; // 7.5 Hz
          case 3: sbs_ao_frames_target=6; break; // 10 Hz
          case 4: sbs_ao_frames_target=5; break; // 12 Hz
          case 5: sbs_ao_frames_target=4; break; // 15 Hz
        }
        if(sbs_ao_frequency_change_flag==1) { // if change of sbs_ao_frequency occurred, set default number of frames during with alternately occluding rectangle occupies left part of the picture
          switch(sbs_ao_frequency) { 
            case 0: sbs_ao_frames_per_left_part=12; break; 
            case 1: sbs_ao_frames_per_left_part=6; break; 
            case 2: sbs_ao_frames_per_left_part=4; break; 
            case 3: sbs_ao_frames_per_left_part=3; break; 
            case 4: sbs_ao_frames_per_left_part=3; break; 
            case 5: sbs_ao_frames_per_left_part=2; break; 
          }
          sbs_ao_frequency_change_flag = 0;
        }

        /* Set total number of frames in a cycle according to sbs_di_period. */
        switch(sbs_di_period) { 
          case 0: sbs_di_frames_target=480; break; // 8s
          case 1: sbs_di_frames_target=280; break; // 4.67s
          case 2: sbs_di_frames_target=200; break; // 3.33s
          case 3: sbs_di_frames_target=120; break; // 2s
          case 4: sbs_di_frames_target=80; break; // 1.33s
          case 5: sbs_di_frames_target=40; break; // 0.67s
        }
        if(sbs_di_period_change_flag==1) { // if change of sbs_di_period occurred, set default number of frames during with dihoptic rectangle occupies left part of the picture
          switch(sbs_di_period) { 
            case 0: sbs_di_frames_per_left_part=240; break; 
            case 1: sbs_di_frames_per_left_part=140; break; 
            case 2: sbs_di_frames_per_left_part=100; break; 
            case 3: sbs_di_frames_per_left_part=60; break; 
            case 4: sbs_di_frames_per_left_part=40; break; 
            case 5: sbs_di_frames_per_left_part=20; break; 
          }
          sbs_di_period_change_flag = 0;
        }

      }
      frames_per_keyboard_read++;


      /* --- Timing and Rendering --- */

      /* Determine where alternately occluding rectangle should appear. */
      sbs_ao_frames_count++;
      if(sbs_ao_frames_count >= sbs_ao_frames_target) sbs_ao_frames_count = 0;
      if(sbs_ao_frames_count < sbs_ao_frames_per_left_part) sbs_ao_position = 1; // left
      else sbs_ao_position = 2; // right

      /* Determine where dihoptic rectangle should appear. */
      sbs_di_frames_count++;
      if( sbs_di_frames_count >= (sbs_di_frames_target + 2*sbs_di_break) ) sbs_di_frames_count = 0;
      if(sbs_di_frames_count < sbs_di_frames_per_left_part) sbs_di_position = 1; // left
      else if( sbs_di_frames_count < (sbs_di_frames_per_left_part + sbs_di_break) ) sbs_di_position = 0; // not visible during the brake
      else if(sbs_di_frames_count < (sbs_di_frames_target + sbs_di_break) ) sbs_di_position = 2; // right
      else sbs_di_position = 0;

      /* Calculate where left edge of alternately occluding rectangle is. */
      if(sbs_ao_position == 2) sbs_ao_left_edge = sbs_ao_gap;
      else sbs_ao_left_edge = 0;

      /* Calculate where edges of dihoptic rectangle are, while making sure they are kept at safe distance from alternately occluding rectangle edges. */
      if(sbs_di_position == 2) {

        sbs_di_left_edge = sbs_di_position_h + sbs_di_offset;
        if( (sbs_di_left_edge<MIN_SBS_DI_POSITION_H) || (sbs_di_left_edge>250) ) sbs_di_left_edge = MIN_SBS_DI_POSITION_H;
        sbs_di_right_edge = sbs_di_position_h + sbs_di_size_h + sbs_di_offset;
        if(sbs_di_right_edge>(sbs_ao_size_h-MIN_SBS_DI_POSITION_H)) sbs_di_right_edge = (sbs_ao_size_h-MIN_SBS_DI_POSITION_H);
        if(sbs_di_right_edge<MIN_SBS_DI_POSITION_H+MIN_SBS_DI_SIZE_H) sbs_di_right_edge = (MIN_SBS_DI_POSITION_H+MIN_SBS_DI_SIZE_H);

        sbs_di_left_edge = sbs_di_left_edge + sbs_ao_gap;
        sbs_di_right_edge = sbs_di_right_edge + sbs_ao_gap;

      }
      else {

        sbs_di_left_edge = sbs_di_position_h;
        sbs_di_right_edge = sbs_di_position_h + sbs_di_size_h;

      }

      /* Calculate number of lines that separate bottom edge of dihoptic rectangle from the bottom edge of alternately occluding rectangle. */
      sbs_di_gap = sbs_ao_size_v - ( sbs_di_position_v + sbs_di_size_v);

      /* SBS mode will display lines using 8-bit Timer/Counter0. First cycle of counter will separate overlay from left edge of the screen, second will be used to draw rectangles on the left part of the screen, */
      /* third one will be used to draw rectangles on the right part of the screen.  */
      OCR0A = sbs_ao_right_edge; // make 8-bit Timer/Counter0 overflow at sbs_ao_right_edge value
      if( sbs_ao_right_edge < sbs_ao_position_h + 5 ) sbs_ao_position_h = sbs_ao_right_edge - 5; // make sure that lenght of does not exceed sbs_ao_right_edge (timer overflow value) minus 5
      sbs_line_beginning = sbs_ao_right_edge - sbs_ao_position_h; // sbs_line_beginning will be initial value of TCNT0, counter will then count until it overflows and then drawing of rectangles will start.


      /* Determine order in with rectangles will be displayed, while taking into account that some rectangles may not be visible or they may be turned off. */
      sbs_objects = ( sbs_di_on_flag << 5 ) | ( sbs_ao_on_flag << 4 ) | ( sbs_di_position << 2 ) | sbs_ao_position;

      switch(sbs_objects) { 

        case 0x01: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x02: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x05: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x06: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x09: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x0a: sbs_objects_order = 0x00; break; // EMPTY, EMPTY

        case 0x11: sbs_objects_order = 0x10; break; // AO, EMPTY
        case 0x12: sbs_objects_order = 0x01; break; // EMPTY, AO
        case 0x15: sbs_objects_order = 0x10; break; // AO, EMPTY
        case 0x16: sbs_objects_order = 0x01; break; // EMPTY, AO
        case 0x19: sbs_objects_order = 0x10; break; // AO, EMPTY
        case 0x1a: sbs_objects_order = 0x01; break; // EMPTY, AO

        case 0x21: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x22: sbs_objects_order = 0x00; break; // EMPTY, EMPTY
        case 0x25: sbs_objects_order = 0x20; break; // DI, EMPTY
        case 0x26: sbs_objects_order = 0x20; break; // DI, EMPTY
        case 0x29: sbs_objects_order = 0x02; break; // EMPTY, DI
        case 0x2a: sbs_objects_order = 0x02; break; // EMPTY, DI

        case 0x31: sbs_objects_order = 0x10; break; // AO, EMPTY
        case 0x32: sbs_objects_order = 0x01; break; // EMPTY, AO
        case 0x35: sbs_objects_order = 0x10; break; // AO, EMPTY
        case 0x36: sbs_objects_order = 0x21; break; // DI, AO
        case 0x39: sbs_objects_order = 0x12; break; // AO, DI
        case 0x3a: sbs_objects_order = 0x01; break; // EMPTY, AO

      }


      /* Determine every rendered line content (which rectangles it contains). */
      switch(sbs_objects_order) { 

        case 0x01: // EMPTY, AO
          for(j = 0; j < sbs_ao_position_v; j++) rendered_line[line_count++] = 0;
          for(j = 0; j < sbs_ao_size_v; j++) rendered_line[line_count++] = 3;       
        break;

        case 0x02: // EMPTY, DI
          for(j = 0; j < sbs_ao_position_v; j++) rendered_line[line_count++] = 0; 
          for(j = 0; j < sbs_di_position_v; j++) rendered_line[line_count++] = 0; 
          for(j = 0; j < sbs_di_size_v; j++) rendered_line[line_count++] = 4;
        break;

        case 0x10: // AO, EMPTY
          for(j = 0; j < sbs_ao_position_v; j++) rendered_line[line_count++] = 0;
          for(j = 0; j < sbs_ao_size_v; j++) rendered_line[line_count++] = 5;   
        break;

        case 0x12: // AO, DI
          for(j = 0; j < sbs_ao_position_v; j++) rendered_line[line_count++] = 0;
          for(j = 0; j < sbs_di_position_v; j++) rendered_line[line_count++] = 5;   
          for(j = 0; j < sbs_di_size_v; j++) rendered_line[line_count++] = 6; 
          for(j = 0; j < sbs_di_gap; j++) rendered_line[line_count++] = 5; 
        break;

        case 0x20: // DI, EMPTY
          for(j = 0; j < sbs_ao_position_v; j++) rendered_line[line_count++] = 0; 
          for(j = 0; j < sbs_di_position_v; j++) rendered_line[line_count++] = 0; 
          for(j = 0; j < sbs_di_size_v; j++) rendered_line[line_count++] = 7;  
        break;

        case 0x21: // DI, AO
          for(j = 0; j < sbs_ao_position_v; j++) rendered_line[line_count++] = 0;
          for(j = 0; j < sbs_di_position_v; j++) rendered_line[line_count++] = 3;   
          for(j = 0; j < sbs_di_size_v; j++) rendered_line[line_count++] = 8; 
          for(j = 0; j < sbs_di_gap; j++) rendered_line[line_count++] = 3;
        break;

      }


    break;


    /* --- FREE FLOATING RECTANGLES --- */
    case 3:


      /* Read keyboard. */
      if(frames_per_keyboard_read == frames_per_keyboard_read_target) { // read keyboard every frames_per_keyboard_read_target
  
        frames_per_keyboard_read_target = 5; // by default every 5 frames (changes when button is pressed)
        frames_per_keyboard_read = 0;

        if( !(MODE_KEY_PORT_IN &= (1 << MODE_KEY)) ) { // if MODE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) { mode++; if(mode >= 4) mode = 0; frames_per_keyboard_read_target = 10; } // and PAGE_KEY is not, change mode to next one
          else { // if MODE_KEY and PAGE_KEY are both pressed, set default settings
            mode = 0;
            page = 5;
            tb_ao_frequency = DEFAULT_TB_AO_FREQUENCY;
            tb_ao_frames_per_upper_part = DEFAULT_TB_AO_FRAMES_PER_UPPER_PART;
            tb_ao_on_flag = DEFAULT_TB_AO_ON_FLAG;
            tb_ao_gap = DEFAULT_TB_AO_GAP;
            tb_ao_position_h = DEFAULT_TB_AO_POSITION_H;
            tb_ao_position_v = DEFAULT_TB_AO_POSITION_V;
            tb_ao_size_h = DEFAULT_TB_AO_SIZE_H;
            tb_ao_size_v = DEFAULT_TB_AO_SIZE_V;
            tb_di_period = DEFAULT_TB_DI_PERIOD;
            tb_di_frames_per_upper_part = DEFAULT_TB_DI_FRAMES_PER_UPPER_PART;
            tb_di_on_flag = DEFAULT_TB_DI_ON_FLAG;
            tb_di_offset = DEFAULT_TB_DI_OFFSET;
            tb_di_break = DEFAULT_TB_DI_BREAK;
            tb_di_position_h = DEFAULT_TB_DI_POSITION_H;
            tb_di_position_v = DEFAULT_TB_DI_POSITION_V;
            tb_di_size_h = DEFAULT_TB_DI_SIZE_H;
            tb_di_size_v = DEFAULT_TB_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FREQUENCY, tb_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FRAMES_PER_UPPER_PART, tb_ao_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_ON_FLAG, tb_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_GAP, tb_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_H, tb_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_V, tb_ao_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_AO_SIZE_H, tb_ao_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_SIZE_V, tb_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_PERIOD, tb_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_FRAMES_PER_UPPER_PART, tb_di_frames_per_upper_part);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_ON_FLAG, tb_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_OFFSET, tb_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_BREAK, tb_di_break);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_POSITION_H, tb_di_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_POSITION_V, tb_di_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_TB_DI_SIZE_H, tb_di_size_h);
            eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_SIZE_V, tb_di_size_v);
            sbs_ao_frequency = DEFAULT_SBS_AO_FREQUENCY;
            sbs_ao_frames_per_left_part = DEFAULT_SBS_AO_FRAMES_PER_LEFT_PART;
            sbs_ao_on_flag = DEFAULT_SBS_AO_ON_FLAG;
            sbs_ao_gap = DEFAULT_SBS_AO_GAP;
            sbs_ao_position_h = DEFAULT_SBS_AO_POSITION_H;
            sbs_ao_position_v = DEFAULT_SBS_AO_POSITION_V;
            sbs_ao_right_edge = DEFAULT_SBS_AO_RIGHT_EDGE;
            sbs_ao_size_v = DEFAULT_SBS_AO_SIZE_V;
            sbs_di_period = DEFAULT_SBS_DI_PERIOD;
            sbs_di_frames_per_left_part = DEFAULT_SBS_DI_FRAMES_PER_LEFT_PART;
            sbs_di_on_flag = DEFAULT_SBS_DI_ON_FLAG;
            sbs_di_offset = DEFAULT_SBS_DI_OFFSET;
            sbs_di_break = DEFAULT_SBS_DI_BREAK;
            sbs_di_position_h = DEFAULT_SBS_DI_POSITION_H;
            sbs_di_position_v = DEFAULT_SBS_DI_POSITION_V;
            sbs_di_size_h = DEFAULT_SBS_DI_SIZE_H;
            sbs_di_size_v = DEFAULT_SBS_DI_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FREQUENCY, sbs_ao_frequency);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FRAMES_PER_LEFT_PART, sbs_ao_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_ON_FLAG, sbs_ao_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_GAP, sbs_ao_gap);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_H, sbs_ao_position_h);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_V, sbs_ao_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_RIGHT_EDGE, sbs_ao_right_edge);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_AO_SIZE_V, sbs_ao_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_PERIOD, sbs_di_period);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_FRAMES_PER_LEFT_PART, sbs_di_frames_per_left_part);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_ON_FLAG, sbs_di_on_flag);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_OFFSET, sbs_di_offset);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_BREAK, sbs_di_break);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_POSITION_H, sbs_di_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_POSITION_V, sbs_di_position_v);
            eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_SIZE_H, sbs_di_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_SIZE_V, sbs_di_size_v);
            ffr_fr_position = DEFAULT_FFR_FR_POSITION;
            ffr_fr_period = DEFAULT_FFR_FR_PERIOD;
            ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART;
            ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG;
            ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H;
            ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
            ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H;
            ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
            ffr_sr_position = DEFAULT_FFR_SR_POSITION;
            ffr_sr_period = DEFAULT_FFR_SR_PERIOD;
            ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART;
            ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG;
            ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H;
            ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
            ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H;
            ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_POSITION, ffr_fr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_PERIOD, ffr_fr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_FRAMES_PER_VISIBLE_PART, ffr_fr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_ON_FLAG, ffr_fr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_H, ffr_fr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_V, ffr_fr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_H, ffr_fr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_V, ffr_fr_size_v);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_POSITION, ffr_sr_position);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_PERIOD, ffr_sr_period);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_FRAMES_PER_VISIBLE_PART, ffr_sr_frames_per_visible_part);
            eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_ON_FLAG, ffr_sr_on_flag);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_H, ffr_sr_position_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_V, ffr_sr_position_v);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_H, ffr_sr_size_h);
            eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_V, ffr_sr_size_v);
            frames_per_keyboard_read_target = 20;
          }
        }
        if( !(KEYBOARD_PORT_IN &= (1 << PAGE_KEY)) ) { // if PAGE_KEY is pressed...
          if(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) { page++; if(page >= 6) page = 0; } // and SHIFT_KEY is not, change page to next one
          else { page--; if(page > 240) page = 5; } // if PAGE_KEY and SHIFT_KEY are both pressed, change page to previous one
          frames_per_keyboard_read_target = 10; // 10 frames till next keyboard read
        }

        /* Store information about other keys in keyboard_state */
        if( !(KEYBOARD_PORT_IN &= (1 << SHIFT_KEY)) ) keyboard_state |= (1 << 4);
        else keyboard_state &= ~(1 << 4);
        if( !(KEYBOARD_PORT_IN &= (1 << LEFT_KEY)) ) keyboard_state |= (1 << 3);
        else keyboard_state &= ~(1 << 3);
        if( !(KEYBOARD_PORT_IN &= (1 << UP_KEY)) ) keyboard_state |= (1 << 2);
        else keyboard_state &= ~(1 << 2);
        if( !(KEYBOARD_PORT_IN &= (1 << DOWN_KEY)) ) keyboard_state |= (1 << 1);
        else keyboard_state &= ~(1 << 1);
        if( !(KEYBOARD_PORT_IN &= (1 << RIGHT_KEY)) ) keyboard_state |= (1 << 0);
        else keyboard_state &= ~(1 << 0);

        switch(page) {
  
          /* First Rectangle Settings */
          case 0: 
            switch(keyboard_state) {

              /* Without the SHIFT_KEY pressed. */
              case 0x01:
                if(ffr_fr_period<=2) ffr_fr_frames_per_visible_part = ffr_fr_frames_per_visible_part + 20; 
                else if(ffr_fr_period==3) ffr_fr_frames_per_visible_part = ffr_fr_frames_per_visible_part + 10;
                else if(ffr_fr_period==4) ffr_fr_frames_per_visible_part = ffr_fr_frames_per_visible_part + 2; 
                else ffr_fr_frames_per_visible_part++; 
                if(ffr_fr_frames_per_visible_part > ffr_fr_frames_target) ffr_fr_frames_per_visible_part = ffr_fr_frames_target;
                frames_per_keyboard_read_target = 10;
              break;
              case 0x02: 
              ffr_fr_period--; if(ffr_fr_period > 240) ffr_fr_period = 0; ffr_fr_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x04: 
              ffr_fr_period++; if(ffr_fr_period > MAX_FFR_FR_PERIOD) ffr_fr_period = MAX_FFR_FR_PERIOD; ffr_fr_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: 
                if(ffr_fr_period<=2) ffr_fr_frames_per_visible_part = ffr_fr_frames_per_visible_part - 20; 
                else if(ffr_fr_period==3) ffr_fr_frames_per_visible_part = ffr_fr_frames_per_visible_part - 10;
                else if(ffr_fr_period==4) ffr_fr_frames_per_visible_part = ffr_fr_frames_per_visible_part - 2; 
                else ffr_fr_frames_per_visible_part--; 
                if(ffr_fr_frames_per_visible_part > 65000) ffr_fr_frames_per_visible_part = 0;
                frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: ffr_fr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x12: ffr_fr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x14: ffr_fr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x18: ffr_fr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: ffr_fr_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x06: ffr_fr_period = DEFAULT_FFR_FR_PERIOD; ffr_fr_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; frames_per_keyboard_read_target = 10; break;
              case 0x16: ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; frames_per_keyboard_read_target = 10; break;
              case 0x0f: 
                ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x1f: 
                ffr_fr_position = 0; ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1;
                ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
                ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
                ffr_sr_position = 1; ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1;
                ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
                ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* First Rectangle Position */
          case 1:
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: ffr_fr_position_h++; frames_per_keyboard_read_target = 10; break;
              case 0x02: 
                ffr_fr_position_v++;
                if( ((ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v) && (ffr_fr_position == 0) ) {
                  ffr_fr_position_v--; 
                  ffr_fr_position_v = ffr_fr_position_v + ffr_sr_size_v;
                  ffr_fr_position = 1;
                  ffr_sr_position_v = ffr_sr_position_v - ffr_fr_size_v;
                  ffr_sr_position = 0;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x04:
                ffr_fr_position_v--; if(ffr_fr_position_v > 65000) ffr_fr_position_v = 0; 
                if( ((ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v) && (ffr_fr_position == 1) ) { 
                  ffr_fr_position_v++;
                  ffr_fr_position_v = ffr_fr_position_v - ffr_sr_size_v;
                  ffr_fr_position = 0;
                  ffr_sr_position_v = ffr_sr_position_v + ffr_fr_size_v;
                  ffr_sr_position = 1;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: ffr_fr_position_h--; if(ffr_fr_position_h < MIN_FFR_FR_POSITION_H) ffr_fr_position_h = MIN_FFR_FR_POSITION_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: 
                ffr_fr_position_h = ffr_fr_position_h + 10; 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x12: 
                ffr_fr_position_v = ffr_fr_position_v + 10; 
                if( ((ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v) && (ffr_fr_position == 0) ) {
                  ffr_fr_position_v = ffr_sr_position_v - ffr_fr_size_v; 
                  ffr_fr_position_v = ffr_fr_position_v + ffr_sr_size_v;
                  ffr_fr_position = 1;
                  ffr_sr_position_v = ffr_sr_position_v - ffr_fr_size_v;
                  ffr_sr_position = 0;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x14:
               ffr_fr_position_v = ffr_fr_position_v - 10; if(ffr_fr_position_v > 65000) ffr_fr_position_v = 0; 
                if( ((ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v) && (ffr_fr_position == 1) ) { 
                  ffr_fr_position_v = ffr_sr_position_v  + ffr_sr_size_v;
                  ffr_fr_position_v = ffr_fr_position_v - ffr_sr_size_v;
                  ffr_fr_position = 0;
                  ffr_sr_position_v = ffr_sr_position_v + ffr_fr_size_v;
                  ffr_sr_position = 1;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x18:
                ffr_fr_position_h = ffr_fr_position_h - 10; if( (ffr_fr_position_h < MIN_FFR_FR_POSITION_H) || (ffr_fr_position_h > 65000) ) ffr_fr_position_h = MIN_FFR_FR_POSITION_H; 
                frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V; ffr_fr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V; ffr_fr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x0f: ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V; ffr_fr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                ffr_fr_position = 0; ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1;
                ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
                ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
                ffr_sr_position = 1; ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1;
                ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
                ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* First Rectangle Size */
          case 2:
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: ffr_fr_size_h++; if( ffr_fr_size_h > MAX_FFR_FR_SIZE_H ) ffr_fr_size_h--; frames_per_keyboard_read_target = 10; break;
              case 0x02: 
                ffr_fr_size_v++; if( ffr_fr_size_v > MAX_FFR_FR_SIZE_V ) ffr_fr_size_v--;
                if( ((ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v) && (ffr_fr_position == 0) ) ffr_fr_size_v--;  
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x04: ffr_fr_size_v--; if(ffr_fr_size_v < MIN_FFR_FR_SIZE_V) ffr_fr_size_v++; frames_per_keyboard_read_target = 10; break;
              case 0x08: ffr_fr_size_h--; if(ffr_fr_size_h < MIN_FFR_FR_SIZE_H) ffr_fr_size_h = MIN_FFR_FR_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: ffr_fr_size_h = ffr_fr_size_h + 10; if( ffr_fr_size_h > MAX_FFR_FR_SIZE_H ) ffr_fr_size_h = MAX_FFR_FR_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x12: 
                ffr_fr_size_v = ffr_fr_size_v + 10; if( ffr_fr_size_v > MAX_FFR_FR_SIZE_V ) ffr_fr_size_v = MAX_FFR_FR_SIZE_V;
                if( ((ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v) && (ffr_fr_position == 0) ) ffr_fr_size_v = ffr_sr_position_v - ffr_fr_position_v; 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x14: ffr_fr_size_v = ffr_fr_size_v - 10; if(ffr_fr_size_v < MIN_FFR_FR_SIZE_V) ffr_fr_size_v = MIN_FFR_FR_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x18: ffr_fr_size_h = ffr_fr_size_h - 10; if(ffr_fr_size_h < MIN_FFR_FR_SIZE_H) ffr_fr_size_h = MIN_FFR_FR_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V; ffr_fr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V; ffr_fr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x0f: ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V; ffr_fr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                ffr_fr_position = 0; ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1;
                ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
                ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
                ffr_sr_position = 1; ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1;
                ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
                ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Second Rectangle Settings */
          case 3:  
            switch(keyboard_state) {

              /* Without the SHIFT_KEY pressed. */
              case 0x01:
                if(ffr_sr_period<=2) ffr_sr_frames_per_visible_part = ffr_sr_frames_per_visible_part + 20; 
                else if(ffr_sr_period==3) ffr_sr_frames_per_visible_part = ffr_sr_frames_per_visible_part + 10;
                else if(ffr_sr_period==4) ffr_sr_frames_per_visible_part = ffr_sr_frames_per_visible_part + 2; 
                else ffr_sr_frames_per_visible_part++; 
                if(ffr_sr_frames_per_visible_part > ffr_sr_frames_target) ffr_sr_frames_per_visible_part = ffr_sr_frames_target;
                frames_per_keyboard_read_target = 10;
              break;
              case 0x02: 
              ffr_sr_period--; if(ffr_sr_period > 240) ffr_sr_period = 0; ffr_sr_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x04: 
              ffr_sr_period++; if(ffr_sr_period > MAX_FFR_SR_PERIOD) ffr_sr_period = MAX_FFR_SR_PERIOD; ffr_sr_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: 
                if(ffr_sr_period<=2) ffr_sr_frames_per_visible_part = ffr_sr_frames_per_visible_part - 20; 
                else if(ffr_sr_period==3) ffr_sr_frames_per_visible_part = ffr_sr_frames_per_visible_part - 10;
                else if(ffr_sr_period==4) ffr_sr_frames_per_visible_part = ffr_sr_frames_per_visible_part - 2; 
                else ffr_sr_frames_per_visible_part--; 
                if(ffr_sr_frames_per_visible_part > 65000) ffr_sr_frames_per_visible_part = 0;
                frames_per_keyboard_read_target = 10;
              break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: ffr_sr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x12: ffr_sr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x14: ffr_sr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;
              case 0x18: ffr_sr_on_flag ^= 0x01; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: ffr_sr_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x06: ffr_sr_period = DEFAULT_FFR_SR_PERIOD; ffr_sr_period_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; frames_per_keyboard_read_target = 10; break;
              case 0x16: ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; frames_per_keyboard_read_target = 10; break;
              case 0x0f: 
                ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1; frames_per_keyboard_read_target = 10; 
              break;
              case 0x1f: 
                ffr_fr_position = 0; ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1;
                ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
                ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
                ffr_sr_position = 1; ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1;
                ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
                ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Second Rectangle Position */
          case 4: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: ffr_sr_position_h++; frames_per_keyboard_read_target = 10; break;
              case 0x02: 
                ffr_sr_position_v++; 
                if( ((ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v) && (ffr_sr_position == 0) ) {
                  ffr_sr_position_v--; 
                  ffr_sr_position_v = ffr_sr_position_v + ffr_fr_size_v;
                  ffr_sr_position = 1;
                  ffr_fr_position_v = ffr_fr_position_v - ffr_sr_size_v;
                  ffr_fr_position = 0;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x04:
                ffr_sr_position_v--; if(ffr_sr_position_v > 65000) ffr_sr_position_v = 0; 
                if( ((ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v) && (ffr_sr_position == 1) ) { 
                  ffr_sr_position_v++;
                  ffr_sr_position_v = ffr_sr_position_v - ffr_fr_size_v;
                  ffr_sr_position = 0;
                  ffr_fr_position_v = ffr_fr_position_v + ffr_sr_size_v;
                  ffr_fr_position = 1;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x08: ffr_sr_position_h--; if(ffr_sr_position_h < MIN_FFR_SR_POSITION_H) ffr_sr_position_h = MIN_FFR_SR_POSITION_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: 
                ffr_sr_position_h = ffr_sr_position_h + 10; 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x12: 
                ffr_sr_position_v = ffr_sr_position_v + 10; 
                if( ((ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v) && (ffr_sr_position == 0) ) {
                  ffr_sr_position_v = ffr_fr_position_v - ffr_sr_size_v; 
                  ffr_sr_position_v = ffr_sr_position_v + ffr_fr_size_v;
                  ffr_sr_position = 1;
                  ffr_fr_position_v = ffr_fr_position_v - ffr_sr_size_v;
                  ffr_fr_position = 0;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x14:
                ffr_sr_position_v = ffr_sr_position_v - 10; if(ffr_sr_position_v > 65000) ffr_sr_position_v = 0; 
                if( ((ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v) && (ffr_sr_position == 1) ) { 
                  ffr_sr_position_v = ffr_fr_position_v  + ffr_fr_size_v;
                  ffr_sr_position_v = ffr_sr_position_v - ffr_fr_size_v;
                  ffr_sr_position = 0;
                  ffr_fr_position_v = ffr_fr_position_v + ffr_sr_size_v;
                  ffr_fr_position = 1;
                } 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x18:
                ffr_sr_position_h = ffr_sr_position_h - 10; if( (ffr_sr_position_h < MIN_FFR_SR_POSITION_H) || (ffr_sr_position_h > 65000) ) ffr_sr_position_h = MIN_FFR_SR_POSITION_H; 
                frames_per_keyboard_read_target = 10; 
              break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V; ffr_sr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V; ffr_sr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x0f: ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V; ffr_sr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                ffr_fr_position = 0; ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1;
                ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
                ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
                ffr_sr_position = 1; ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1;
                ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
                ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;

          /* Second Rectangle Size */
          case 5: 
            switch(keyboard_state) { 

              /* Without the SHIFT_KEY pressed. */
              case 0x01: ffr_sr_size_h++; if( ffr_sr_size_h > MAX_FFR_SR_SIZE_H ) ffr_sr_size_h--; frames_per_keyboard_read_target = 10; break;
              case 0x02: 
                ffr_sr_size_v++; if( ffr_sr_size_v > MAX_FFR_SR_SIZE_V ) ffr_sr_size_v--;
                if( ((ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v) && (ffr_sr_position == 0) ) ffr_sr_size_v--;  
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x04: ffr_sr_size_v--; if(ffr_sr_size_v < MIN_FFR_SR_SIZE_V) ffr_sr_size_v++; frames_per_keyboard_read_target = 10; break;
              case 0x08: ffr_sr_size_h--; if(ffr_sr_size_h < MIN_FFR_SR_SIZE_H) ffr_sr_size_h = MIN_FFR_SR_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* With the SHIFT_KEY pressed. */
              case 0x11: ffr_sr_size_h = ffr_sr_size_h + 10; if( ffr_sr_size_h > MAX_FFR_SR_SIZE_H ) ffr_sr_size_h = MAX_FFR_SR_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x12: 
                ffr_sr_size_v = ffr_sr_size_v + 10; if( ffr_sr_size_v > MAX_FFR_SR_SIZE_V ) ffr_sr_size_v = MAX_FFR_SR_SIZE_V;
                if( ((ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v) && (ffr_sr_position == 0) ) ffr_sr_size_v = ffr_fr_position_v - ffr_sr_position_v; 
                frames_per_keyboard_read_target = 10; 
              break;
              case 0x14: ffr_sr_size_v = ffr_sr_size_v - 10; if(ffr_sr_size_v < MIN_FFR_SR_SIZE_V) ffr_sr_size_v = MIN_FFR_SR_SIZE_V; frames_per_keyboard_read_target = 10; break;
              case 0x18: ffr_sr_size_h = ffr_sr_size_h - 10; if(ffr_sr_size_h < MIN_FFR_SR_SIZE_H) ffr_sr_size_h = MIN_FFR_SR_SIZE_H; frames_per_keyboard_read_target = 10; break;

              /* Restoring default settings by pressing 2, 4 or 5 buttons at the same time. */
              case 0x09: ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x06: ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V; ffr_sr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x19: ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; frames_per_keyboard_read_target = 10; break;
              case 0x16: ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V; ffr_sr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x0f: ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V; ffr_sr_v_values_change_flag = 1; frames_per_keyboard_read_target = 10; break;
              case 0x1f: 
                ffr_fr_position = 0; ffr_fr_frames_per_visible_part = DEFAULT_FFR_FR_FRAMES_PER_VISIBLE_PART; ffr_fr_period = DEFAULT_FFR_FR_PERIOD; 
                ffr_fr_on_flag = DEFAULT_FFR_FR_ON_FLAG; ffr_fr_period_change_flag = 1;
                ffr_fr_position_h = DEFAULT_FFR_FR_POSITION_H; ffr_fr_position_v = DEFAULT_FFR_FR_POSITION_V;
                ffr_fr_size_h = DEFAULT_FFR_FR_SIZE_H; ffr_fr_size_v = DEFAULT_FFR_FR_SIZE_V;
                ffr_sr_position = 1; ffr_sr_frames_per_visible_part = DEFAULT_FFR_SR_FRAMES_PER_VISIBLE_PART; ffr_sr_period = DEFAULT_FFR_SR_PERIOD; 
                ffr_sr_on_flag = DEFAULT_FFR_SR_ON_FLAG; ffr_sr_period_change_flag = 1;
                ffr_sr_position_h = DEFAULT_FFR_SR_POSITION_H; ffr_sr_position_v = DEFAULT_FFR_SR_POSITION_V;
                ffr_sr_size_h = DEFAULT_FFR_SR_SIZE_H; ffr_sr_size_v = DEFAULT_FFR_SR_SIZE_V;
                page = 0;
                frames_per_keyboard_read_target = 20;
              break;

            }
          break;


        }


        /* When instant change of vertical values occurs during restoration of default settings, make sure that rectangles don't occupy the same lines. */

        if(ffr_fr_v_values_change_flag) {
          if( (ffr_sr_position_v + ffr_sr_size_v) < ffr_fr_position_v ) {
            ffr_fr_position = 1;
            ffr_sr_position = 0;
          }
          else if( ffr_sr_position_v < ffr_fr_position_v ) {
            if( (ffr_sr_position_v + ffr_sr_size_v) < (ffr_fr_position_v + ffr_fr_size_v) ) {
              ffr_fr_position = 1;
              ffr_sr_position = 0;
              ffr_sr_size_v = MIN_FFR_SR_SIZE_V;
              ffr_sr_position_v = ffr_fr_position_v - ffr_sr_size_v;
            }
            else {
              ffr_fr_position = 0;
              ffr_sr_position = 1;
              ffr_sr_size_v = MIN_FFR_SR_SIZE_V;
              ffr_sr_position_v = ffr_fr_position_v + ffr_fr_size_v;
            }
          }
          else if( ffr_sr_position_v < (ffr_fr_position_v + ffr_fr_size_v) ) {
            if( (ffr_sr_position_v + ffr_sr_size_v) < (ffr_fr_position_v + ffr_fr_size_v) ) {
              ffr_fr_position = 0;
              ffr_sr_position = 1;
              ffr_sr_size_v = MIN_FFR_SR_SIZE_V;
              ffr_sr_position_v = ffr_fr_position_v + ffr_fr_size_v;
            }
            else {
              ffr_fr_position = 0;
              ffr_sr_position = 1;
              ffr_sr_size_v = MIN_FFR_SR_SIZE_V;
              ffr_sr_position_v = ffr_fr_position_v + ffr_fr_size_v;
            }
          }
          else {
            ffr_fr_position = 0;
            ffr_sr_position = 1;
          }
          ffr_fr_v_values_change_flag = 0;
        }

        if(ffr_sr_v_values_change_flag) {
          if( (ffr_fr_position_v + ffr_fr_size_v) < ffr_sr_position_v ) {
            ffr_fr_position = 0;
            ffr_sr_position = 1;
          }
          else if( ffr_fr_position_v < ffr_sr_position_v ) {
            if( (ffr_fr_position_v + ffr_fr_size_v) < (ffr_sr_position_v + ffr_sr_size_v) ) {
              ffr_fr_position = 0;
              ffr_sr_position = 1;
              ffr_fr_size_v = MIN_FFR_FR_SIZE_V;
              ffr_fr_position_v = ffr_sr_position_v - ffr_fr_size_v;
            }
            else {
              ffr_fr_position = 0;
              ffr_sr_position = 1;
              ffr_fr_size_v = MIN_FFR_FR_SIZE_V;
              ffr_fr_position_v = ffr_sr_position_v - ffr_fr_size_v;
            }
          }
          else if( ffr_sr_position_v < (ffr_fr_position_v + ffr_fr_size_v) ) {
            if( (ffr_sr_position_v + ffr_sr_size_v) < (ffr_fr_position_v + ffr_fr_size_v) ) {
              ffr_fr_position = 0;
              ffr_sr_position = 1;
              ffr_fr_size_v = MIN_FFR_FR_SIZE_V;
              ffr_fr_position_v = ffr_sr_position_v - ffr_fr_size_v;
            }
            else {
              ffr_fr_position = 1;
              ffr_sr_position = 0;
              ffr_fr_size_v = MIN_FFR_FR_SIZE_V;
              ffr_fr_position_v = ffr_sr_position_v + ffr_sr_size_v;
            }
          }
          else {
            ffr_fr_position = 1;
            ffr_sr_position = 0;
          }
          ffr_sr_v_values_change_flag = 0;
        }


        /* Make sure that maximum number of lines is not exceeded and that rectangles don't occupy the same lines.. */
        if(ffr_sr_position) {
          if( (ffr_sr_position_v  + ffr_sr_size_v) > MAX_FFR_SR_POSITION_V ) {
            ffr_sr_size_v = MAX_FFR_SR_POSITION_V - ffr_sr_position_v;
            if( (ffr_sr_size_v > 65000) || (ffr_sr_size_v < MIN_FFR_SR_SIZE_V) ) { 
              ffr_sr_size_v = MIN_FFR_SR_SIZE_V;
              if( (ffr_sr_position_v  + ffr_sr_size_v) > MAX_FFR_SR_POSITION_V ) ffr_sr_position_v = MAX_FFR_SR_POSITION_V - MIN_FFR_SR_SIZE_V;     
            } 
            if( (ffr_fr_position_v  + ffr_fr_size_v) > ffr_sr_position_v ) {
              ffr_fr_position_v = ffr_sr_position_v - ffr_fr_size_v;
              if(ffr_fr_position_v > 65000) { 
                ffr_fr_position_v = MIN_FFR_FR_POSITION_V;
                ffr_fr_size_v = ffr_sr_position_v;
              } 
            }
          }
        }
        else {
          if( (ffr_fr_position_v  + ffr_fr_size_v) > MAX_FFR_FR_POSITION_V ) {
            ffr_fr_size_v = MAX_FFR_FR_POSITION_V - ffr_fr_position_v;
            if( (ffr_fr_size_v > 65000) || (ffr_fr_size_v < MIN_FFR_FR_SIZE_V) ) { 
              ffr_fr_size_v = MIN_FFR_FR_SIZE_V;
              if( (ffr_fr_position_v  + ffr_fr_size_v) > MAX_FFR_FR_POSITION_V ) ffr_fr_position_v = MAX_FFR_FR_POSITION_V - MIN_FFR_FR_SIZE_V;     
            } 
            if( (ffr_sr_position_v  + ffr_sr_size_v) > ffr_fr_position_v ) {
              ffr_sr_position_v = ffr_fr_position_v - ffr_sr_size_v;
              if(ffr_sr_position_v > 65000) { 
                ffr_sr_position_v = MIN_FFR_SR_POSITION_V;
                ffr_sr_size_v = ffr_fr_position_v;
              } 
            }
          }
        }

        /* Make sure that right edge of each rectangle doesn't move farther to the right than MAX_FFR_SR_POSITION_H */
        if( (ffr_fr_position_h  + ffr_fr_size_h) > MAX_FFR_FR_POSITION_H ) ffr_fr_position_h = MAX_FFR_FR_POSITION_H - ffr_fr_size_h; 
        if( (ffr_sr_position_h  + ffr_sr_size_h) > MAX_FFR_SR_POSITION_H ) ffr_sr_position_h = MAX_FFR_SR_POSITION_H - ffr_sr_size_h; 

        switch(ffr_fr_period) { 
          case 0: ffr_fr_frames_target=280; break; // 4.67s
          case 1: ffr_fr_frames_target=120; break; // 2s
          case 2: ffr_fr_frames_target=80; break; // 1.33s
          case 3: ffr_fr_frames_target=40; break; // 0.67s
          case 4: ffr_fr_frames_target=24; break; // 2.5 Hz
          case 5: ffr_fr_frames_target=12; break; // 5 Hz
          case 6: ffr_fr_frames_target=8; break; // 7.5 Hz
          case 7: ffr_fr_frames_target=6; break; // 10 Hz
          case 8: ffr_fr_frames_target=5; break; // 12 Hz
          case 9: ffr_fr_frames_target=4; break; // 15 Hz
        }
        if(ffr_fr_period_change_flag==1) {
          switch(ffr_fr_period) { 
            case 0: ffr_fr_frames_per_visible_part=140; break; 
            case 1: ffr_fr_frames_per_visible_part=60; break; 
            case 2: ffr_fr_frames_per_visible_part=40; break; 
            case 3: ffr_fr_frames_per_visible_part=20; break; 
            case 4: ffr_fr_frames_per_visible_part=12; break; 
            case 5: ffr_fr_frames_per_visible_part=6; break; 
            case 6: ffr_fr_frames_per_visible_part=4; break; 
            case 7: ffr_fr_frames_per_visible_part=3; break; 
            case 8: ffr_fr_frames_per_visible_part=3; break; 
            case 9: ffr_fr_frames_per_visible_part=2; break; 
          }
          ffr_fr_period_change_flag = 0;
        }


        switch(ffr_sr_period) { 
          case 0: ffr_sr_frames_target=280; break; // 4.67s
          case 1: ffr_sr_frames_target=120; break; // 2s
          case 2: ffr_sr_frames_target=80; break; // 1.33s
          case 3: ffr_sr_frames_target=40; break; // 0.67s
          case 4: ffr_sr_frames_target=24; break; // 2.5 Hz
          case 5: ffr_sr_frames_target=12; break; // 5 Hz
          case 6: ffr_sr_frames_target=8; break; // 7.5 Hz
          case 7: ffr_sr_frames_target=6; break; // 10 Hz
          case 8: ffr_sr_frames_target=5; break; // 12 Hz
          case 9: ffr_sr_frames_target=4; break; // 15 Hz
        }
        if(ffr_sr_period_change_flag==1) {
          switch(ffr_sr_period) { 
            case 0: ffr_sr_frames_per_visible_part=140; break; 
            case 1: ffr_sr_frames_per_visible_part=60; break; 
            case 2: ffr_sr_frames_per_visible_part=40; break; 
            case 3: ffr_sr_frames_per_visible_part=20; break; 
            case 4: ffr_sr_frames_per_visible_part=12; break; 
            case 5: ffr_sr_frames_per_visible_part=6; break; 
            case 6: ffr_sr_frames_per_visible_part=4; break; 
            case 7: ffr_sr_frames_per_visible_part=3; break; 
            case 8: ffr_sr_frames_per_visible_part=3; break; 
            case 9: ffr_sr_frames_per_visible_part=2; break; 
          }
          ffr_sr_period_change_flag = 0;
        }

      }
      frames_per_keyboard_read++;


      /* --- Timing and Rendering --- */

      /* Determine when first rectangle should appear. */
      ffr_fr_frames_count++;
      if(ffr_fr_frames_count >= ffr_fr_frames_target) ffr_fr_frames_count = 0;
      if(ffr_fr_frames_count < ffr_fr_frames_per_visible_part) ffr_fr_visible = 1;
      else ffr_fr_visible = 0;

      /* Determine when second rectangle should appear. */
      ffr_sr_frames_count++;
      if(ffr_sr_frames_count >= ffr_sr_frames_target) ffr_sr_frames_count = 0;
      if(ffr_sr_frames_count < ffr_sr_frames_per_visible_part) ffr_sr_visible = 1;
      else ffr_sr_visible = 0;

      /* Calculate where edges of first rectangle are. Use top-bottom alternately occluding rectangle variables to store it. */
      tb_ao_left_edge = ffr_fr_position_h;
      tb_ao_right_edge = ffr_fr_position_h + ffr_fr_size_h;

      /* Calculate where edges of second rectangle are. Use top-bottom dihoptic rectangle variables to store it. */
      tb_di_left_edge = ffr_sr_position_h;
      tb_di_right_edge = ffr_sr_position_h + ffr_sr_size_h;

      /* Calculate number of lines that separate two rectangles. */
      if(ffr_fr_position) ffr_gap = ffr_fr_position_v - ( ffr_sr_position_v + ffr_sr_size_v);
      else ffr_gap = ffr_sr_position_v - ( ffr_fr_position_v + ffr_fr_size_v);

      /* Combine information about rectangles being on an visible. */
      ffr_fr_visible &= ffr_fr_on_flag;
      ffr_sr_visible &= ffr_sr_on_flag;


      /* Determine order in with rectangles will be displayed, while taking into account that some rectangles may not be visible or they may be turned off. */
      ffr_objects = ( ffr_sr_visible << 5 ) | ( ffr_fr_visible << 4 ) | ffr_fr_position;

      switch(ffr_objects) { 

        case 0x00: ffr_objects_order = 0x00; break; // EMPTY
        case 0x01: ffr_objects_order = 0x00; break; // EMPTY

        case 0x10: ffr_objects_order = 0x11; break; // FR
        case 0x11: ffr_objects_order = 0x11; break; // FR

        case 0x20: ffr_objects_order = 0x22; break; // SR
        case 0x21: ffr_objects_order = 0x22; break; // SR

        case 0x30: ffr_objects_order = 0x12; break; // FR, SR
        case 0x31: ffr_objects_order = 0x21; break; // SR, FR

      }


      /* Determine every rendered line content (which rectangle it contains). */
      switch(ffr_objects_order) { 

        case 0x11: 
          for(j = 0; j < ffr_fr_position_v; j++) rendered_line[line_count++] = 0;  
          for(j = 0; j < ffr_fr_size_v; j++) rendered_line[line_count++] = 1;      
        break;

        case 0x22: 
          for(j = 0; j < ffr_sr_position_v; j++) rendered_line[line_count++] = 0;  
          for(j = 0; j < ffr_sr_size_v; j++) rendered_line[line_count++] = 2;  
        break;

        case 0x12: 
          for(j = 0; j < ffr_fr_position_v; j++) rendered_line[line_count++] = 0;  
          for(j = 0; j < ffr_fr_size_v; j++) rendered_line[line_count++] = 1; 
          for(j = 0; j < ffr_gap; j++) rendered_line[line_count++] = 0;
          for(j = 0; j < ffr_sr_size_v; j++) rendered_line[line_count++] = 2;  
        break;

        case 0x21: 
          for(j = 0; j < ffr_sr_position_v; j++) rendered_line[line_count++] = 0;  
          for(j = 0; j < ffr_sr_size_v; j++) rendered_line[line_count++] = 2;  
          for(j = 0; j < ffr_gap; j++) rendered_line[line_count++] = 0;
          for(j = 0; j < ffr_fr_size_v; j++) rendered_line[line_count++] = 1;  
        break;

      }


    break;


  }


  /* Fill rest of the lines witch 0's. */
  while(line_count <= 274) rendered_line[line_count++] = 0;

  /* Reset count of line that is currently being worked on. */
  line_count = 0;
  line_pair = 0;


  /* Wait for there to be 600 frames of no button being pressed, then save setting to EEPROM. */

  if(frames_per_keyboard_read_target >= 10) frames_to_settings_save = 0;
  else frames_to_settings_save++;
  if(frames_to_settings_save >= 600) {

    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FREQUENCY, tb_ao_frequency);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_FRAMES_PER_UPPER_PART, tb_ao_frames_per_upper_part);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_ON_FLAG, tb_ao_on_flag);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_GAP, tb_ao_gap);

    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_H, tb_ao_position_h);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_POSITION_V, tb_ao_position_v);
    eeprom_update_word((uint16_t*)ADDRESS_TB_AO_SIZE_H, tb_ao_size_h);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_AO_SIZE_V, tb_ao_size_v);

    eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_PERIOD, tb_di_period);
    eeprom_update_word((uint16_t*)ADDRESS_TB_DI_FRAMES_PER_UPPER_PART, tb_di_frames_per_upper_part);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_ON_FLAG, tb_di_on_flag);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_OFFSET, tb_di_offset);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_BREAK, tb_di_break);

    eeprom_update_word((uint16_t*)ADDRESS_TB_DI_POSITION_H, tb_di_position_h);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_POSITION_V, tb_di_position_v);
    eeprom_update_word((uint16_t*)ADDRESS_TB_DI_SIZE_H, tb_di_size_h);
    eeprom_update_byte((uint8_t*)ADDRESS_TB_DI_SIZE_V, tb_di_size_v);

    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FREQUENCY, sbs_ao_frequency);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_FRAMES_PER_LEFT_PART, sbs_ao_frames_per_left_part);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_ON_FLAG, sbs_ao_on_flag);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_GAP, sbs_ao_gap);

    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_H, sbs_ao_position_h);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_POSITION_V, sbs_ao_position_v);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_AO_RIGHT_EDGE, sbs_ao_right_edge);
    eeprom_update_word((uint16_t*)ADDRESS_SBS_AO_SIZE_V, sbs_ao_size_v);

    eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_PERIOD, sbs_di_period);
    eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_FRAMES_PER_LEFT_PART, sbs_di_frames_per_left_part);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_ON_FLAG, sbs_di_on_flag);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_OFFSET, sbs_di_offset);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_BREAK, sbs_di_break);

    eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_POSITION_H, sbs_di_position_h);
    eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_POSITION_V, sbs_di_position_v);
    eeprom_update_byte((uint8_t*)ADDRESS_SBS_DI_SIZE_H, sbs_di_size_h);
    eeprom_update_word((uint16_t*)ADDRESS_SBS_DI_SIZE_V, sbs_di_size_v);

    eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_POSITION, ffr_fr_position);
    eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_PERIOD, ffr_fr_period);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_FRAMES_PER_VISIBLE_PART, ffr_fr_frames_per_visible_part);
    eeprom_update_byte((uint8_t*)ADDRESS_FFR_FR_ON_FLAG, ffr_fr_on_flag);

    eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_H, ffr_fr_position_h);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_POSITION_V, ffr_fr_position_v);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_H, ffr_fr_size_h);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_FR_SIZE_V, ffr_fr_size_v);

    eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_POSITION, ffr_sr_position);
    eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_PERIOD, ffr_sr_period);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_FRAMES_PER_VISIBLE_PART, ffr_sr_frames_per_visible_part);
    eeprom_update_byte((uint8_t*)ADDRESS_FFR_SR_ON_FLAG, ffr_sr_on_flag);

    eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_H, ffr_sr_position_h);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_POSITION_V, ffr_sr_position_v);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_H, ffr_sr_size_h);
    eeprom_update_word((uint16_t*)ADDRESS_FFR_SR_SIZE_V, ffr_sr_size_v);

    frames_to_settings_save = 0;
  }


  /* LEDs */

  switch(page) { 

    case 0: PAGE_LED_PORT_OUT &= ~( (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT) ); break; // page 0, no blue LED lights up
    case 1: PAGE_LED_PORT_OUT &= ~(1 << PAGE_LED_LEFT); PAGE_LED_PORT_OUT |= (1 << PAGE_LED_RIGHT); break; // page 1, right blue LED lights up
    case 2: PAGE_LED_PORT_OUT |= (1 << PAGE_LED_LEFT); PAGE_LED_PORT_OUT &= ~(1 << PAGE_LED_RIGHT); break; // page 2, left blue LED lights up
    case 3: PAGE_LED_PORT_OUT |= (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT); break; // page 3, both blue LEDs light up

    case 4: // page 4, both blue LEDs blink at lower frequency
    if(page_flash < 6){ PAGE_LED_PORT_OUT |= (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT); }
    else{ PAGE_LED_PORT_OUT &= ~( (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT) ); }
    page_flash++;
    if(page_flash >= 12) page_flash = 0;
    break;

    case 5: // page 5, both blue LEDs blink at higher frequency
    if(page_flash < 3){ PAGE_LED_PORT_OUT |= (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT); }
    else{ PAGE_LED_PORT_OUT &= ~( (1 << PAGE_LED_LEFT) | (1 << PAGE_LED_RIGHT) ); }
    page_flash++;
    if(page_flash >= 6) page_flash = 0;
    break;

  }

  switch(mode) { 
    case 0: MODE_LED_PORT_OUT &= ~( (1 << MODE_LED_UP) | (1 << MODE_LED_DOWN) ); break; // mode 0, no yellow LED lights up
    case 1: MODE_LED_PORT_OUT |= (1 << MODE_LED_DOWN); MODE_LED_PORT_OUT &= ~(1 << MODE_LED_UP); break; // mode 1, lower yellow LED lights up
    case 2: MODE_LED_PORT_OUT &= ~(1 << MODE_LED_DOWN); MODE_LED_PORT_OUT |= (1 << MODE_LED_UP); break; // mode 2, upper yellow LED lights up
    case 3: MODE_LED_PORT_OUT |= (1 << MODE_LED_UP) | (1 << MODE_LED_DOWN); break; // mode 3, both yellow LEDs light up
  }


  TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve

  TIMSK1 |= (1 << OCIE1B) | (1 << OCIE1A); // enable 16-bit Timer/Counter1 compare match interrupts


}  




/* Set high state at MUX_OUTPUT and start drawing overlay in current line. */
ISR(TIMER1_COMPA_vect, ISR_NAKED) {
  MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT); 
  reti();
}




/* Set low state at MUX_OUTPUT and stop drawing overlay in current line. */
ISR(TIMER1_COMPB_vect, ISR_NAKED) {
  MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT); 
  reti();
}




/* Hsync interrupt. Drawing rectangles in lines is done here. */
ISR(INT0_vect, ISR_NOBLOCK) {

  /* Set counter registers to their initial values. */
  TCNT1 = 0; // it will be used in TB / FFR modes line drawing
  TCNT0 = sbs_line_beginning; // it will be used in SBS mode line drawing

  /* Draw lines accordingly to data stored in rendered_line. */
  switch(rendered_line[line_count]) { 

    case 1: // Alternately Occluding Rectangle (TB) / First Rectangle (FFR)
      OCR1A = tb_ao_left_edge;
      OCR1B = tb_ao_right_edge;
    break;

    case 2: // Dihoptic Rectangle (TB) / Second Rectangle (FFR)
      OCR1A = tb_di_left_edge;
      OCR1B = tb_di_right_edge;
    break;

    case 0: // no rectangles in a line
      TCNT1 = 1024; 
    break;

    case 3: // EMPTY, AO (SBS)
      TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve
      while(TCNT0 > sbs_line_beginning);
      while(TCNT0 < 10);
      while(TCNT0 > 10);
      while(TCNT0 < sbs_ao_left_edge);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 > 10);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
    break;

    case 4: // EMPTY, DI (SBS)
      TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve
      while(TCNT0 > sbs_line_beginning);
      while(TCNT0 < 10);
      while(TCNT0 > 10);
      while(TCNT0 < sbs_di_left_edge);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 < sbs_di_right_edge);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
    break;

    case 5: // AO, EMPTY (SBS)
      TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve
      while(TCNT0 > sbs_line_beginning);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 < sbs_ao_size_h);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
    break;

    case 6: // AO, DI (SBS)
      TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve
      while(TCNT0 > sbs_line_beginning);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 < sbs_ao_size_h);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
      while(TCNT0 > 10);
      while(TCNT0 < sbs_di_left_edge);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 < sbs_di_right_edge);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
    break;

    case 7: // DI, EMPTY (SBS)
      TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve
      while(TCNT0 > sbs_line_beginning);
      while(TCNT0 < sbs_di_left_edge);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 < sbs_di_right_edge);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);

    break;

    case 8: // DI, AO (SBS)
      TCNT1 = 1024; // set Timer/Counter Register of 16-bit Timer/Counter1 above any value that compare registers can achieve
      while(TCNT0 > sbs_line_beginning);
      while(TCNT0 < sbs_di_left_edge);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 < sbs_di_right_edge);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
      while(TCNT0 > 10);
      while(TCNT0 < sbs_ao_left_edge);
      MUX_OUTPUT_PORT_OUT |= (1 << MUX_OUTPUT);
      while(TCNT0 > 10);
      MUX_OUTPUT_PORT_OUT &= ~(1 << MUX_OUTPUT);
    break;

  }


  /* Every rendered line of overlay is drawn on 4 lines of VGA signal. */
  if( (line_pair++) == 3) {
    line_pair = 0;  
    line_count++;
  }


}