PVS-Studio warning V205 for NetXMS

static int hash_void_ptr(void *ptr)
{
  int hash;
  int i;

  /* I took this hash function just off the top of my head,
     I have no idea whether it is bad or very bad. */
  hash = 0;
  for (i = 0; i < (int)sizeof(ptr)*8 / TABLE_BITS; i++)
    {
      hash ^= (unsigned long)ptr >> i*8;
      hash += i * 17;
      hash &= TABLE_MASK;
    }
  return hash;
}

This suspicious code was found in NetXMS project by PVS-Studio static code analyzer.
Warning message is:
V205 Explicit conversion of pointer type to 32-bit integer type: (unsigned long) ptr xmalloc.c 85

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