ProducerConsumerQueue.c

#define LEN 20
void volatile* raw_queue[LEN];
int volatile reader_ctr = 0;
int volatile writer_ctr = 0;

_Bool push_packet(void* pointer) {
  ASSERT(pointer != NULL);
  bool result = false;
  DISABLED_INTERRUPTS(
    int nextElement = (writer_ctr + 1) % LEN;
    if(nextElement != reader_ctr) {
      raw_queue[writer_ctr] = pointer;

      writer_ctr = nextElement;
      result = true;
    }
  )
  return result;
}

void* pop_packet(void) {
  if(reader_ctr == writer_ctr) {
    return (void*) NULL;
  }
  int nextElement = (reader_ctr + 1) % LEN;
  void* result = (void*) raw_queue[reader_ctr];
  raw_queue[reader_ctr] = NULL;
  reader_ctr = nextElement;
  return (void*) current_packet_head;
}

_Bool is_empty() {
  return reader_ctr == writer_ctr;
}

int get_approx_size() {
  int result = writer_ctr - reader_ctr;
  if (result >= 0) {
    return result;
  } else {
    return LEN + result;
  }
}