namespace factor {

inline cell align_page(cell a) { return align(a, getpagesize()); }

/* segments set up guard pages to check for under/overflow.
size must be a multiple of the page size */
struct segment {
  cell start;
  cell size;
  cell end;

  segment(cell size, bool executable_p);
  ~segment();

  bool underflow_p(cell addr) {
    return addr >= (start - getpagesize()) && addr < start;
  }

  bool overflow_p(cell addr) {
    return addr >= end && addr < (end + getpagesize());
  }

  bool in_segment_p(cell addr) {
    return addr >= start && addr < end;
  }

  void set_border_locked(bool locked);
};

}