c - 32 bit number handling with ATTiny and Atmel Studio -

i wondering how attiny, attiny24 stores 32 bit unsigned ints in memory. i'm trying take 32 bit value , write 32 bit location in eeprom. have attempted use simple mask, every time try, lower 2 bytes (lsb) correctly , upper 2 bytes zeros. example, when try write: 0x12345678 output is: 0x00005678. there setting in atmel studio need set, or need use method other masking.

ultimately want able read 32 bit counter value , write specific location in eeprom. working on modifying existing circuit , not have luxury debug serial output.

code snippets:

in main:

unsigned long test_val = 305419896;  //0x12345678 eeprom_long_write(0x25,test_val); 

functions:

eeprom_long_write:

void eeprom_long_write(unsigned char eeadr, unsigned long ee_data) {     unsigned char temp=0;     unsigned char count= eeadr + 3;     unsigned long mask=0;     unsigned char position=24;       while (eeadr <= count)     {         mask = ((1<<8)-1) << position;         temp = (ee_data & mask) >> position;         eeprom_write(eeadr, temp);         position = position-8;         eeadr++;     } } 

eeprom_write:

void eeprom_write(unsigned char ucaddress, unsigned char ucdata) {        while(eecr & (1<<eepe));        //wait completion of previous write     eecr =(0<<eepm1) | (0>>eepm0);  // set programming mode     eearl = ucaddress;              // setup address , data registers     eedr = ucdata;                  // load data register     eecr |= (1<<eempe);             // write logical 1 eempe     eecr |= (1<<eepe);              // start eeprom write setting eepe  } 

you fell pit of integer promotion , coercion. ((1<<8)-1) processed int, not long (better: uint32_t). on avr, int has minimum size allowed standard: 16 bits.

as is anyway complicated, can use following:

uint8_t shift = 32u;   // enough enough {     shift -= 8u;     eeprom_write(eeadr++, (uint8_t)(ee_data >> shift)); } while ( shift ) ; 

this safes 1 additional shift , explicit masking , registers.

note use of stdint.h types (you have include header, of course). should correct declarations accordingly. cast uint8_t implies masking.