void shift_array_left(unsigned long* arr, int size){
    int i = 0;

    for(arr;size--;++arr){
        /*curr_carry = ~(~0UL >> 1) & *arr;
        *arr <<= 1;
        if( prev_carry ) *arr |= 1UL;
        prev_carry = curr_carry;*/

        if( ~(~0UL >> 1) & *arr ){  /* if there is a carry */
            *arr <<= 1;
            ++arr;
            *arr |= 1UL;
            --size;
        }else{
            *arr <<= 1;
        }
    }
}