text: void * memmove(void *dst, void *src, int n)
  {
      char *d, *s;
  
      d = dst;
      s = src;
      if (dst < src) {
          while (n-- > 0)
              *d++ = *s++;
      } else {
          d += n;
          s += n;
          while (n-- > 0)
              *--d = *--s;
      }
  
      return dst;
  }
  