Huge String Array Handling with F macro / reserve()

martyscorpion · December 11, 2019, 8:01am

Hi everyone ;

I am devoloping a control system which has a huge menu ..

I am using a String array for it.

String menu[10][10][10]; Each has 40 chars max. these array values never changes at run time ..

menu[0][0][1].reserve(40); // All array is reserved 40 one by one ..

I am using the F macro to store them also .

as menu[0][0][1] = (F("Something));

using ((char *)0); for empty ones as menu[0][0][0] = ((char *)0);

Is it any way to do best with Strings without using to many RAMs ..

is it neccesary using F macro and reserve together

// This is what I do simply 

String menu[10][10][10];



 void set_menuReserves(){

  

	for(int i= 0; i<10;i++){
		for(int ii= 0; ii<10;ii++){
			for(int iii= 0; iii<10;iii++){
				menu[i][ii][iii].reserve(40);
                                
                               menu[i][ii][iii]=((char *)0); // At startup set all as empty Strings instead of using ""
			}
		}
		
	}

}

void fillArrays(){

  // ALL levels has some Text like  and called only at setup();

  menu[0][0][0] = (F("SOMETHING 000"));

  /.
  /.
  /.
  /.
 menu[10][10][10] = (F("SOMETHING TILL 999 array"));

}

void setup(){

  set_menuReserves();

  fillArrays();


}

johnwasser · December 11, 2019, 3:48pm

I don't think you can put a String in PROGMEM/FLASH. I would expect 1000 Strings objects to be way more than most Arduinos can store in RAM. You CAN put character pointers into PROGMEM/FLASH and those character pointers can point to character arrays that are in PROGMEM/FLASH.

const char Menu5_5_5[] PROGMEM = "Menu Item at 5,5,5";


const char * const Menus[10][10][10] PROGMEM =
{
  { // 0
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  { // 1
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  { // 2
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}, // 0
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  { // 3
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  { // 4
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  { // 5
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}, // 0
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}, // 1
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}, // 2
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}, // 3
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}, // 4
    {NULL, NULL, NULL, NULL, NULL, Menu5_5_5, NULL, NULL, NULL, NULL}, // 5
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  {
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  {
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  {
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  },
  {
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
  }
};


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


void loop()
{


  for (int i = 0; i < 10; i++)
  {
    for (int ii = 0; ii < 10; ii++)
    {
      for (int iii = 0; iii < 10; iii++)
      {
        if (pgm_read_word(Menus[i][ii][iii]) != 0)
        {
          Serial.print("foo");
        }
      }
    }
  }
}

system · December 11, 2019, 4:09pm

Which MCU is used? If ATmega328p, that is not possible, it have only 32K words flash space. EEPROM here is 1K only, thus not possible as well.

It's hard to believe that each string will be 40 characters long, however you will missing space for your firmware.

There is several solutions:

External EEPROM, as 24C512. It is cheap and trivial to use.
SD card
Anything else which will allow you to store massive amount of data you may need (Windbond chip, perhaps).

Inside ATmega1280/2560 or similar that would be possible, however all depends on your actual firmware space requirement.

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Huge String Array Handling with F macro / reserve()

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