Pointers as array, copying to memory locations help

Well, basically the program should copy the ints a, b, c to destinations x, y, z.....

Haven't done C in a while and trying to get back on my feet.......
Pointers are getting somewhat confusing.....
The copy function was written way back....when I still knew C well...
The rest was written recently......
I put in nops as assembly as sort of, indentations in assembly so i can compare them to the C...


When you rarely speak a language, you forget it....i guess the same is true with programming languages....

Can someone help me debug this code........

Here is my code

Code:

---

#include <stdio.h>

int ptrcopy(int *src, int *dest, int len)
{
asm("nop");
    int result = 0;
        asm("nop");
    while (len > 0) {
        int val = *src++;
        asm("nop");
        *dest++ = val;
        asm("nop");
        result ^= val;
        asm("nop");
        len--;
        asm("nop");
    }
        asm("nop");
    return result;
}



int main()
{
asm("nop");


/* source */
int a = 0x123;
int b = 0x456;
int c = 0x789;

asm("nop");
/* destination */
int x = 0x111;
int y = 0x222;
int z = 0x333;

asm("nop");

int  source = a;

int destination = x;

asm("nop");


        printf( " %d \n", ptrcopy(source,destination,3)  );

asm("nop");

}

---

Instead of a, b, c to x, y, z, you should be using arrays. It might be helpful to throw a couple printf's in to see what is going on in places of interest.

Code:

---

#include <stdio.h>

int ptrcopy(int *src, int *dest, int len)
{
  int result = 0;
  while ( len > 0 )
  {
      int val = *src++;
      *dest++ = val;
      result ^= val;
      len--;
  }
  return result;
}

int main()
{
  int a[] = {0x123, 0x456, 0x789};
  int x[] = {0x111, 0x222, 0x333};
  int i;
  for ( i = 0; i < 3; ++i )
  {
      printf("a[%d] = %x, x[%d] = %x\n", i, a[ i ], i, x[ i ]);
  }
  printf("result = %d\n", ptrcopy(a,x,3));
  for ( i = 0; i < 3; ++i )
  {
      printf("a[%d] = %x, x[%d] = %x\n", i, a[ i ], i, x[ i ]);
  }
  return 0;
}

/* my output
a[0] = 123, x[0] = 111
a[1] = 456, x[1] = 222
a[2] = 789, x[2] = 333
result = 764
a[0] = 123, x[0] = 123
a[1] = 456, x[1] = 456
a[2] = 789, x[2] = 789
*/

---

The function ptrcopy copies from one array to another, calculates some sort of checksum (an LRC?), and returns the calculated result.