stdatomic.h

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// -*- C++ -*- compatibility header.

// Copyright (C) 2008, 2009 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This 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 General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file stdatomic.h
 *  This is a Standard C++ Library header.
 */

#include <bits/c++config.h>
#include <stddef.h>
#include <stdbool.h> // XXX need to define bool w/o stdbool.h in tr1/cstdbool

#ifndef _GLIBCXX_STDATOMIC_H
#define _GLIBCXX_STDATOMIC_H 1

_GLIBCXX_BEGIN_NAMESPACE(std)
_GLIBCXX_BEGIN_EXTERN_C

  /**
   * @defgroup atomics Atomics
   *
   * Components for performing atomic operations.
   * @{
   */

  /// Enumeration for memory_order
  typedef enum memory_order 
    {
      memory_order_relaxed, 
      memory_order_consume, 
      memory_order_acquire, 
      memory_order_release,
      memory_order_acq_rel, 
      memory_order_seq_cst
    } memory_order;

  // Base for atomic_flag.
  typedef struct __atomic_flag_base
  {
    bool _M_i;
  } __atomic_flag_base;

#define ATOMIC_FLAG_INIT { false } 

  /// 29.2 Lock-free Property
#if defined(_GLIBCXX_ATOMIC_BUILTINS_1) && defined(_GLIBCXX_ATOMIC_BUILTINS_2) \
  && defined(_GLIBCXX_ATOMIC_BUILTINS_4) && defined(_GLIBCXX_ATOMIC_BUILTINS_8)
# define _GLIBCXX_ATOMIC_PROPERTY 2
# define _GLIBCXX_ATOMIC_NAMESPACE __atomic2
#elif defined(_GLIBCXX_ATOMIC_BUILTINS_1)
# define _GLIBCXX_ATOMIC_PROPERTY 1
# define _GLIBCXX_ATOMIC_NAMESPACE __atomic1
#else
# define _GLIBCXX_ATOMIC_PROPERTY 0
# define _GLIBCXX_ATOMIC_NAMESPACE __atomic0
#endif

#define ATOMIC_INTEGRAL_LOCK_FREE _GLIBCXX_ATOMIC_PROPERTY
#define ATOMIC_ADDRESS_LOCK_FREE _GLIBCXX_ATOMIC_PROPERTY

  // Switch atomic integral base types based on C or C++.  In
  // addition, for "C" only provide type-generic macros for atomic
  // operations. (As C++ accomplishes the same thing with sets of
  // overloaded functions.
#ifdef __cplusplus
  inline namespace _GLIBCXX_ATOMIC_NAMESPACE { }
# include <bits/atomicfwd_cxx.h>
#else
# include <bits/atomicfwd_c.h>
#endif
  
  // Typedefs for other atomic integral types.
  typedef atomic_schar      atomic_int_least8_t;
  typedef atomic_uchar      atomic_uint_least8_t;
  typedef atomic_short      atomic_int_least16_t;
  typedef atomic_ushort     atomic_uint_least16_t;
  typedef atomic_int        atomic_int_least32_t;
  typedef atomic_uint       atomic_uint_least32_t;
  typedef atomic_llong      atomic_int_least64_t;
  typedef atomic_ullong     atomic_uint_least64_t;

  typedef atomic_schar      atomic_int_fast8_t;
  typedef atomic_uchar      atomic_uint_fast8_t;
  typedef atomic_short      atomic_int_fast16_t;
  typedef atomic_ushort     atomic_uint_fast16_t;
  typedef atomic_int        atomic_int_fast32_t;
  typedef atomic_uint       atomic_uint_fast32_t;
  typedef atomic_llong      atomic_int_fast64_t;
  typedef atomic_ullong     atomic_uint_fast64_t;

  typedef atomic_long       atomic_intptr_t;
  typedef atomic_ulong      atomic_uintptr_t;

  typedef atomic_long       atomic_ssize_t;
  typedef atomic_ulong      atomic_size_t;

  typedef atomic_llong      atomic_intmax_t;
  typedef atomic_ullong     atomic_uintmax_t;

  typedef atomic_long       atomic_ptrdiff_t;

  // Accessor functions for base atomic_flag type.
  bool 
  atomic_flag_test_and_set_explicit(volatile __atomic_flag_base*, memory_order);

  inline bool 
  atomic_flag_test_and_set(volatile __atomic_flag_base* __a)
  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }
  
  void 
  atomic_flag_clear_explicit(volatile __atomic_flag_base*, memory_order);

  inline void 
  atomic_flag_clear(volatile __atomic_flag_base* __a)
  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }

  void 
  __atomic_flag_wait_explicit(volatile __atomic_flag_base*, memory_order);
  
  volatile __atomic_flag_base* 
  __atomic_flag_for_address(const volatile void* __z) __attribute__((const));

  // Implementation specific defines.
#define _ATOMIC_LOAD_(__a, __x)                     \
  ({ volatile __typeof__ _ATOMIC_MEMBER_* __p = &_ATOMIC_MEMBER_;   \
     volatile atomic_flag* __g = __atomic_flag_for_address(__p);    \
    __atomic_flag_wait_explicit(__g, __x);              \
    __typeof__ _ATOMIC_MEMBER_ __r = *__p;              \
    atomic_flag_clear_explicit(__g, __x);                   \
    __r; })

#define _ATOMIC_STORE_(__a, __m, __x)                   \
  ({ volatile __typeof__ _ATOMIC_MEMBER_* __p = &_ATOMIC_MEMBER_;   \
    __typeof__(__m) __v = (__m);                        \
    volatile atomic_flag* __g = __atomic_flag_for_address(__p);     \
    __atomic_flag_wait_explicit(__g, __x);              \
    *__p = __v;                             \
    atomic_flag_clear_explicit(__g, __x);                   \
    __v; })

#define _ATOMIC_MODIFY_(__a, __o, __m, __x)             \
  ({ volatile __typeof__ _ATOMIC_MEMBER_* __p = &_ATOMIC_MEMBER_;   \
    __typeof__(__m) __v = (__m);                        \
    volatile atomic_flag* __g = __atomic_flag_for_address(__p);     \
    __atomic_flag_wait_explicit(__g, __x);              \
    __typeof__ _ATOMIC_MEMBER_ __r = *__p;              \
    *__p __o __v;                               \
    atomic_flag_clear_explicit(__g, __x);                   \
    __r; })

#define _ATOMIC_CMPEXCHNG_(__a, __e, __m, __x)              \
  ({ volatile __typeof__ _ATOMIC_MEMBER_* __p = &_ATOMIC_MEMBER_;   \
    __typeof__(__e) __q = (__e);                        \
    __typeof__(__m) __v = (__m);                        \
    bool __r;                                   \
    volatile atomic_flag* __g = __atomic_flag_for_address(__p);     \
    __atomic_flag_wait_explicit(__g, __x);              \
    __typeof__ _ATOMIC_MEMBER_ __t__ = *__p;                    \
    if (__t__ == *__q) { *__p = __v; __r = true; }          \
    else { *__q = __t__; __r = false; }                     \
    atomic_flag_clear_explicit(__g, __x);                   \
    __r; })

  // @} group atomics

_GLIBCXX_END_EXTERN_C
_GLIBCXX_END_NAMESPACE

// Inject into global namespace. XXX
#if defined(__cplusplus) && !defined(_GLIBCXX_STDATOMIC)
using std::memory_order;
using std::memory_order_relaxed;
using std::memory_order_consume;
using std::memory_order_acquire;
using std::memory_order_release;
using std::memory_order_acq_rel;
using std::memory_order_seq_cst;
using std::atomic_flag;
using std::atomic_bool;
using std::atomic_char;
using std::atomic_schar;
using std::atomic_uchar;
using std::atomic_short;
using std::atomic_ushort;
using std::atomic_int;
using std::atomic_uint;
using std::atomic_long;
using std::atomic_ulong;
using std::atomic_llong;
using std::atomic_ullong;
using std::atomic_wchar_t;
using std::atomic_char16_t;
using std::atomic_char32_t;
using std::atomic_address;
using std::atomic;
#endif

#endif