#include "stdio.h"
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE - 1)

int main(int argc, char * argv[]) {
	volatile unsigned int *base, *address;
	unsigned long addr1, addr2, addr0, offset, value;
  int val1, val2, result;
  //Predefined addresses.
  //Write the values to be added to addr1 and addr2
  //Read the result from addr0
  addr0 = strtoul("0xd3000000", 0, 0);
  addr1 = strtoul("0xd3000004", 0, 0);
  addr2 = strtoul("0xd3000008", 0, 0);

  //Ensure proper usage
  if(argc != 3)
  {
    printf("Usage: %s value1 value2\n",argv[0]);
    return -1;
  }
  //assign val1 and val2
  val1 = atoi(argv[1]);
  val2 = atoi(argv[2]);


  //Open memory as a file
	int fd = open("/dev/mem", O_RDWR|O_SYNC);
	if(!fd)
	{
		printf("Unable to open /dev/mem.  Ensure it exists (major=1, minor=1)\n");
		return -1;
	}

  //Map the base address to base
	base = (unsigned int *)mmap(NULL, MAP_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, addr0 & ~MAP_MASK);
  if((base == MAP_FAILED))
  {
    printf("mapping failed\n");
    fflush(stdout);
  }

  //Write to addr1
  address = base + ((addr1 & MAP_MASK)>>2);
  *address = val1;

  //Write to addr2
  address = base + ((addr2 & MAP_MASK)>>2);
  *address = val2;

  //Read from addr0. The result should be the sum of val1 and val2
  address = base + ((addr0 & MAP_MASK)>>2);
  result = *address;

  printf("The sum of %d and %d is %d\n", val1, val2, result);

  //In the end, unmap the base address and close the memory file
  munmap(base,MAP_SIZE);
	close(fd);
	return 0;
}