zZzzZ. — /usr/include/bits

Editing: atomic_wide_counter.h

/* Monotonically increasing wide counters (at least 62 bits).
   Copyright (C) 2016-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef _BITS_ATOMIC_WIDE_COUNTER_H
#define _BITS_ATOMIC_WIDE_COUNTER_H

/* Counter that is monotonically increasing (by less than 2**31 per
   increment), with a single writer, and an arbitrary number of
   readers.  */
typedef union
{
  __extension__ unsigned long long int __value64;
  struct
  {
    unsigned int __low;
    unsigned int __high;
  } __value32;
} __atomic_wide_counter;

#endif /* _BITS_ATOMIC_WIDE_COUNTER_H */