Newbie memory question

So for now:

I use Eclipse because the tutorials I found tell me to do that and I don't know how to do it otherwise but I don't think it's relevant.

I don't really understand what is wrong:

I have a hardware part that is writing the memory. I know it's correct as I'm writing "01010101" and the LEDs of my DE0-NANO board are ok when reading the memory. But when using this code:

#include <stdio.h>
# define ONCHIP_MEM_BASE 0x10000
int main()
{
  int *pmem=(int*)(0x80000000|ONCHIP_MEM_BASE);
  printf("Hello from Nios II!\n");
  usleep(1000000);
  printf("%04x\n",*pmem);
  return 0;
}

the console is printing:

--- Quote Start ---

Hello from Nios II!

820014

--- Quote End ---

Please tell me what is wrong in my code.

Another question:

the system.h file is not read, I have to write the# define line so it's correct. How could I include that automatically?