//could use 1/8th the memory if these were kept in groups of 8 bits as a byte in an array
//12 columns and 8 rows
//but you'd need to figure out how to modify the byte in the right column when you want to make a change


//check these out
//https://web.archive.org/web/20170627135321/https://www.avrfreaks.net/comment/26024
//edit macros to accept one position number, use it to pick byte in array and bit in the byte

#define BIT(x) (0x01 << (x % 8))
//#define BIT(x) (0x01 << (x))



#define nRow 4
#define nCol 12

  byte myArray[nRow] = {
      B11111111,
      B01010101,
      B00000101,
      B00001010
    };

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  




  
}

void loop() {
  // put your main code here, to run repeatedly:
  byte data;
  for (int nr =0; nr < nRow; nr++) {
  //    for (int nc =0; nc < nCol; nc++) {

 data = myArray[nr];
 for (int i = 0; i < 8; i++)
   {
       // consider leftmost bit
       // set line high if bit is 1, low if bit is 0
       if (data & 0x80)
          Serial.print("X");
           //output_high(SD_DI);
       else
           //output_low(SD_DI);
          Serial.print(" ");
       // pulse the clock state to indicate that bit value should be read
      // output_low(SD_CLK);
       //delay();
       //output_high(SD_CLK);

       // shift byte left so next bit will be leftmost
       data <<= 1;
   }



  //    }
    Serial.println("");  
  }


        Serial.println(""); 
            Serial.println(""); 

  myArray[2] ^= B00010000;  //xor  alternates the 4th item of the 2nd row
  myArray[3] ^= B01010010;  //xor  alternates all but the 4th item of the 3nd row
  myArray[1] = 0xff - myArray[1];
  delay(1000); // this speeds up the simulation
  //Serial.println(sizeof(myArray));
  delay(1000);
}