atomic_0.h

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

// Copyright (C) 2008, 2009, 2010, 2011
// 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 bits/atomic_0.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{atomic}
 */

#ifndef _GLIBCXX_ATOMIC_0_H
#define _GLIBCXX_ATOMIC_0_H 1

#pragma GCC system_header

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

// 0 == __atomic0 == Never lock-free
namespace __atomic0
{
  _GLIBCXX_BEGIN_EXTERN_C

  void
  atomic_flag_clear_explicit(__atomic_flag_base*, memory_order)
  _GLIBCXX_NOTHROW;

  void
  __atomic_flag_wait_explicit(__atomic_flag_base*, memory_order)
  _GLIBCXX_NOTHROW;

  _GLIBCXX_CONST __atomic_flag_base*
  __atomic_flag_for_address(const volatile void* __z) _GLIBCXX_NOTHROW;

  _GLIBCXX_END_EXTERN_C

  // Implementation specific defines.
#define _ATOMIC_MEMBER_ _M_i

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

#define _ATOMIC_STORE_(__a, __n, __x)                      \
  ({typedef __typeof__(_ATOMIC_MEMBER_) __i_type;                          \
    __i_type* __p = &_ATOMIC_MEMBER_;                      \
    __typeof__(__n) __w = (__n);                           \
    __atomic_flag_base* __g = __atomic_flag_for_address(__p);          \
    __atomic_flag_wait_explicit(__g, __x);                 \
    *__p = __w;                                \
    atomic_flag_clear_explicit(__g, __x);                      \
    __w; })

#define _ATOMIC_MODIFY_(__a, __o, __n, __x)                \
  ({typedef __typeof__(_ATOMIC_MEMBER_) __i_type;                          \
    __i_type* __p = &_ATOMIC_MEMBER_;                      \
    __typeof__(__n) __w = (__n);                           \
    __atomic_flag_base* __g = __atomic_flag_for_address(__p);          \
    __atomic_flag_wait_explicit(__g, __x);                 \
    __i_type __r = *__p;                               \
    *__p __o __w;                                  \
    atomic_flag_clear_explicit(__g, __x);                      \
    __r; })

#define _ATOMIC_CMPEXCHNG_(__a, __e, __n, __x)                 \
  ({typedef __typeof__(_ATOMIC_MEMBER_) __i_type;                          \
    __i_type* __p = &_ATOMIC_MEMBER_;                      \
    __typeof__(__e) __q = (__e);                           \
    __typeof__(__n) __w = (__n);                           \
    bool __r;                                      \
    __atomic_flag_base* __g = __atomic_flag_for_address(__p);          \
    __atomic_flag_wait_explicit(__g, __x);                 \
    __i_type __t = *__p;                               \
    if (*__q == __t)                               \
      {                                    \
    *__p = (__i_type)__w;                          \
    __r = true;                            \
      }                                    \
    else { *__q = __t; __r = false; }                          \
    atomic_flag_clear_explicit(__g, __x);                      \
    __r; })


  /// atomic_flag
  struct atomic_flag : public __atomic_flag_base
  {
    atomic_flag() = default;
    ~atomic_flag() = default;
    atomic_flag(const atomic_flag&) = delete;
    atomic_flag& operator=(const atomic_flag&) = delete;
    atomic_flag& operator=(const atomic_flag&) volatile = delete;

    // Conversion to ATOMIC_FLAG_INIT.
    atomic_flag(bool __i): __atomic_flag_base({ __i }) { }

    bool
    test_and_set(memory_order __m = memory_order_seq_cst);

    bool
    test_and_set(memory_order __m = memory_order_seq_cst) volatile;

    void
    clear(memory_order __m = memory_order_seq_cst);

    void
    clear(memory_order __m = memory_order_seq_cst) volatile;
  };


  /// Base class for atomic integrals.
  //
  // For each of the integral types, define atomic_[integral type] struct
  //
  // atomic_bool     bool
  // atomic_char     char
  // atomic_schar    signed char
  // atomic_uchar    unsigned char
  // atomic_short    short
  // atomic_ushort   unsigned short
  // atomic_int      int
  // atomic_uint     unsigned int
  // atomic_long     long
  // atomic_ulong    unsigned long
  // atomic_llong    long long
  // atomic_ullong   unsigned long long
  // atomic_char16_t char16_t
  // atomic_char32_t char32_t
  // atomic_wchar_t  wchar_t

  // Base type.
  // NB: Assuming _ITp is an integral scalar type that is 1, 2, 4, or 8 bytes,
  // since that is what GCC built-in functions for atomic memory access work on.
  template<typename _ITp>
    struct __atomic_base
    {
    private:
      typedef _ITp  __int_type;

      __int_type    _M_i;

    public:
      __atomic_base() = default;
      ~__atomic_base() = default;
      __atomic_base(const __atomic_base&) = delete;
      __atomic_base& operator=(const __atomic_base&) = delete;
      __atomic_base& operator=(const __atomic_base&) volatile = delete;

      // Requires __int_type convertible to _M_base._M_i.
      constexpr __atomic_base(__int_type __i): _M_i (__i) { }

      operator __int_type() const
      { return load(); }

      operator __int_type() const volatile
      { return load(); }

      __int_type
      operator=(__int_type __i)
      {
    store(__i);
    return __i;
      }

      __int_type
      operator=(__int_type __i) volatile
      {
    store(__i);
    return __i;
      }

      __int_type
      operator++(int)
      { return fetch_add(1); }

      __int_type
      operator++(int) volatile
      { return fetch_add(1); }

      __int_type
      operator--(int)
      { return fetch_sub(1); }

      __int_type
      operator--(int) volatile
      { return fetch_sub(1); }

      __int_type
      operator++()
      { return fetch_add(1) + 1; }

      __int_type
      operator++() volatile
      { return fetch_add(1) + 1; }

      __int_type
      operator--()
      { return fetch_sub(1) - 1; }

      __int_type
      operator--() volatile
      { return fetch_sub(1) - 1; }

      __int_type
      operator+=(__int_type __i)
      { return fetch_add(__i) + __i; }

      __int_type
      operator+=(__int_type __i) volatile
      { return fetch_add(__i) + __i; }

      __int_type
      operator-=(__int_type __i)
      { return fetch_sub(__i) - __i; }

      __int_type
      operator-=(__int_type __i) volatile
      { return fetch_sub(__i) - __i; }

      __int_type
      operator&=(__int_type __i)
      { return fetch_and(__i) & __i; }

      __int_type
      operator&=(__int_type __i) volatile
      { return fetch_and(__i) & __i; }

      __int_type
      operator|=(__int_type __i)
      { return fetch_or(__i) | __i; }

      __int_type
      operator|=(__int_type __i) volatile
      { return fetch_or(__i) | __i; }

      __int_type
      operator^=(__int_type __i)
      { return fetch_xor(__i) ^ __i; }

      __int_type
      operator^=(__int_type __i) volatile
      { return fetch_xor(__i) ^ __i; }

      bool
      is_lock_free() const
      { return false; }

      bool
      is_lock_free() const volatile
      { return false; }

      void
      store(__int_type __i, memory_order __m = memory_order_seq_cst)
      {
    __glibcxx_assert(__m != memory_order_acquire);
    __glibcxx_assert(__m != memory_order_acq_rel);
    __glibcxx_assert(__m != memory_order_consume);
    _ATOMIC_STORE_(this, __i, __m);
      }

      void
      store(__int_type __i, memory_order __m = memory_order_seq_cst) volatile
      {
    __glibcxx_assert(__m != memory_order_acquire);
    __glibcxx_assert(__m != memory_order_acq_rel);
    __glibcxx_assert(__m != memory_order_consume);
    _ATOMIC_STORE_(this, __i, __m);
      }

      __int_type
      load(memory_order __m = memory_order_seq_cst) const
      {
    __glibcxx_assert(__m != memory_order_release);
    __glibcxx_assert(__m != memory_order_acq_rel);
    return _ATOMIC_LOAD_(this, __m);
      }

      __int_type
      load(memory_order __m = memory_order_seq_cst) const volatile
      {
    __glibcxx_assert(__m != memory_order_release);
    __glibcxx_assert(__m != memory_order_acq_rel);
    return _ATOMIC_LOAD_(this, __m);
      }

      __int_type
      exchange(__int_type __i, memory_order __m = memory_order_seq_cst)
      { return _ATOMIC_MODIFY_(this, =, __i, __m); }

      __int_type
      exchange(__int_type __i, memory_order __m = memory_order_seq_cst) volatile
      { return _ATOMIC_MODIFY_(this, =, __i, __m); }

      bool
      compare_exchange_weak(__int_type& __i1, __int_type __i2,
                memory_order __m1, memory_order __m2)
      {
    __glibcxx_assert(__m2 != memory_order_release);
    __glibcxx_assert(__m2 != memory_order_acq_rel);
    __glibcxx_assert(__m2 <= __m1);
    return _ATOMIC_CMPEXCHNG_(this, &__i1, __i2, __m1);
      }

      bool
      compare_exchange_weak(__int_type& __i1, __int_type __i2,
                memory_order __m1, memory_order __m2) volatile
      {
    __glibcxx_assert(__m2 != memory_order_release);
    __glibcxx_assert(__m2 != memory_order_acq_rel);
    __glibcxx_assert(__m2 <= __m1);
    return _ATOMIC_CMPEXCHNG_(this, &__i1, __i2, __m1);
      }

      bool
      compare_exchange_weak(__int_type& __i1, __int_type __i2,
                memory_order __m = memory_order_seq_cst)
      {
    return compare_exchange_weak(__i1, __i2, __m,
                     __calculate_memory_order(__m));
      }

      bool
      compare_exchange_weak(__int_type& __i1, __int_type __i2,
                memory_order __m = memory_order_seq_cst) volatile
      {
    return compare_exchange_weak(__i1, __i2, __m,
                     __calculate_memory_order(__m));
      }

      bool
      compare_exchange_strong(__int_type& __i1, __int_type __i2,
                  memory_order __m1, memory_order __m2)
      {
    __glibcxx_assert(__m2 != memory_order_release);
    __glibcxx_assert(__m2 != memory_order_acq_rel);
    __glibcxx_assert(__m2 <= __m1);
    return _ATOMIC_CMPEXCHNG_(this, &__i1, __i2, __m1);
      }

      bool
      compare_exchange_strong(__int_type& __i1, __int_type __i2,
                  memory_order __m1, memory_order __m2) volatile
      {
    __glibcxx_assert(__m2 != memory_order_release);
    __glibcxx_assert(__m2 != memory_order_acq_rel);
    __glibcxx_assert(__m2 <= __m1);
    return _ATOMIC_CMPEXCHNG_(this, &__i1, __i2, __m1);
      }

      bool
      compare_exchange_strong(__int_type& __i1, __int_type __i2,
                  memory_order __m = memory_order_seq_cst)
      {
    return compare_exchange_strong(__i1, __i2, __m,
                       __calculate_memory_order(__m));
      }

      bool
      compare_exchange_strong(__int_type& __i1, __int_type __i2,
                  memory_order __m = memory_order_seq_cst) volatile
      {
    return compare_exchange_strong(__i1, __i2, __m,
                       __calculate_memory_order(__m));
      }

      __int_type
      fetch_add(__int_type __i, memory_order __m = memory_order_seq_cst)
      { return _ATOMIC_MODIFY_(this, +=, __i, __m); }

      __int_type
      fetch_add(__int_type __i,
        memory_order __m = memory_order_seq_cst) volatile
      { return _ATOMIC_MODIFY_(this, +=, __i, __m); }

      __int_type
      fetch_sub(__int_type __i, memory_order __m = memory_order_seq_cst)
      { return _ATOMIC_MODIFY_(this, -=, __i, __m); }

      __int_type
      fetch_sub(__int_type __i,
        memory_order __m = memory_order_seq_cst) volatile
      { return _ATOMIC_MODIFY_(this, -=, __i, __m); }

      __int_type
      fetch_and(__int_type __i, memory_order __m = memory_order_seq_cst)
      { return _ATOMIC_MODIFY_(this, &=, __i, __m); }

      __int_type
      fetch_and(__int_type __i,
        memory_order __m = memory_order_seq_cst) volatile
      { return _ATOMIC_MODIFY_(this, &=, __i, __m); }

      __int_type
      fetch_or(__int_type __i, memory_order __m = memory_order_seq_cst)
      { return _ATOMIC_MODIFY_(this, |=, __i, __m); }

      __int_type
      fetch_or(__int_type __i, memory_order __m = memory_order_seq_cst) volatile
      { return _ATOMIC_MODIFY_(this, |=, __i, __m); }

      __int_type
      fetch_xor(__int_type __i, memory_order __m = memory_order_seq_cst)
      { return _ATOMIC_MODIFY_(this, ^=, __i, __m); }

      __int_type
      fetch_xor(__int_type __i,
        memory_order __m = memory_order_seq_cst) volatile
      { return _ATOMIC_MODIFY_(this, ^=, __i, __m); }
    };


  /// Partial specialization for pointer types.
  template<typename _PTp>
    struct __atomic_base<_PTp*>
    {
    private:
      typedef _PTp*     __return_pointer_type;
      typedef void*     __pointer_type;
      __pointer_type    _M_i;

    public:
      __atomic_base() = default;
      ~__atomic_base() = default;
      __atomic_base(const __atomic_base&) = delete;
      __atomic_base& operator=(const __atomic_base&) = delete;
      __atomic_base& operator=(const __atomic_base&) volatile = delete;

      // Requires __pointer_type convertible to _M_i.
      constexpr __atomic_base(__return_pointer_type __p): _M_i (__p) { }

      operator __return_pointer_type() const
      { return reinterpret_cast<__return_pointer_type>(load()); }

      operator __return_pointer_type() const volatile
      { return reinterpret_cast<__return_pointer_type>(load()); }

      __return_pointer_type
      operator=(__pointer_type __p)
      {
    store(__p);
    return reinterpret_cast<__return_pointer_type>(__p);
      }

      __return_pointer_type
      operator=(__pointer_type __p) volatile
      {
    store(__p);
    return reinterpret_cast<__return_pointer_type>(__p);
      }

      __return_pointer_type
      operator++(int)
      { return reinterpret_cast<__return_pointer_type>(fetch_add(1)); }

      __return_pointer_type
      operator++(int) volatile
      { return reinterpret_cast<__return_pointer_type>(fetch_add(1)); }

      __return_pointer_type
      operator--(int)
      { return reinterpret_cast<__return_pointer_type>(fetch_sub(1)); }

      __return_pointer_type
      operator--(int) volatile
      { return reinterpret_cast<__return_pointer_type>(fetch_sub(1)); }

      __return_pointer_type
      operator++()
      { return reinterpret_cast<__return_pointer_type>(fetch_add(1) + 1); }

      __return_pointer_type
      operator++() volatile
      { return reinterpret_cast<__return_pointer_type>(fetch_add(1) + 1); }

      __return_pointer_type
      operator--()
      { return reinterpret_cast<__return_pointer_type>(fetch_sub(1) - 1); }

      __return_pointer_type
      operator--() volatile
      { return reinterpret_cast<__return_pointer_type>(fetch_sub(1) - 1); }

      __return_pointer_type
      operator+=(ptrdiff_t __d)
      { return reinterpret_cast<__return_pointer_type>(fetch_add(__d) + __d); }

      __return_pointer_type
      operator+=(ptrdiff_t __d) volatile
      { return reinterpret_cast<__return_pointer_type>(fetch_add(__d) + __d); }

      __return_pointer_type
      operator-=(ptrdiff_t __d)
      { return reinterpret_cast<__return_pointer_type>(fetch_sub(__d) - __d); }

      __return_pointer_type
      operator-=(ptrdiff_t __d) volatile
      { return reinterpret_cast<__return_pointer_type>(fetch_sub(__d) - __d); }

      bool
      is_lock_free() const
      { return true; }

      bool
      is_lock_free() const volatile
      { return true; }

      void
      store(__pointer_type __p, memory_order __m = memory_order_seq_cst)
      {
    __glibcxx_assert(__m != memory_order_acquire);
    __glibcxx_assert(__m != memory_order_acq_rel);
    __glibcxx_assert(__m != memory_order_consume);
    _ATOMIC_STORE_(this, __p, __m);
      }

      void
      store(__pointer_type __p,
        memory_order __m = memory_order_seq_cst) volatile
      {
    __glibcxx_assert(__m != memory_order_acquire);
    __glibcxx_assert(__m != memory_order_acq_rel);
    __glibcxx_assert(__m != memory_order_consume);
    volatile __pointer_type* __p2 = &_M_i;
    __typeof__(__p) __w = (__p);
    __atomic_flag_base* __g = __atomic_flag_for_address(__p2);
    __atomic_flag_wait_explicit(__g, __m);
    *__p2 = reinterpret_cast<__pointer_type>(__w);
    atomic_flag_clear_explicit(__g, __m);
    __w;
      }

      __return_pointer_type
      load(memory_order __m = memory_order_seq_cst) const
      {
    __glibcxx_assert(__m != memory_order_release);
    __glibcxx_assert(__m != memory_order_acq_rel);
    void* __v = _ATOMIC_LOAD_(this, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }

      __return_pointer_type
      load(memory_order __m = memory_order_seq_cst) const volatile
      {
    __glibcxx_assert(__m != memory_order_release);
    __glibcxx_assert(__m != memory_order_acq_rel);
    void* __v = _ATOMIC_LOAD_(this, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }

      __return_pointer_type
      exchange(__pointer_type __p, memory_order __m = memory_order_seq_cst)
      {
    void* __v = _ATOMIC_MODIFY_(this, =, __p, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }

      __return_pointer_type
      exchange(__pointer_type __p,
           memory_order __m = memory_order_seq_cst) volatile
      {
    volatile __pointer_type* __p2 = &_M_i;
    __typeof__(__p) __w = (__p);
    __atomic_flag_base* __g = __atomic_flag_for_address(__p2);
    __atomic_flag_wait_explicit(__g, __m);
    __pointer_type __r = *__p2;
    *__p2 = __w;
    atomic_flag_clear_explicit(__g, __m);
    __r;
    return reinterpret_cast<__return_pointer_type>(_M_i);
      }

      bool
      compare_exchange_strong(__return_pointer_type& __rp1, __pointer_type __p2,
                  memory_order __m1, memory_order __m2)
      {
    __glibcxx_assert(__m2 != memory_order_release);
    __glibcxx_assert(__m2 != memory_order_acq_rel);
    __glibcxx_assert(__m2 <= __m1);
    __pointer_type& __p1 = reinterpret_cast<void*&>(__rp1);
    return _ATOMIC_CMPEXCHNG_(this, &__p1, __p2, __m1);
      }

      bool
      compare_exchange_strong(__return_pointer_type& __rp1, __pointer_type __p2,
                  memory_order __m1, memory_order __m2) volatile
      {
    __glibcxx_assert(__m2 != memory_order_release);
    __glibcxx_assert(__m2 != memory_order_acq_rel);
    __glibcxx_assert(__m2 <= __m1);
    __pointer_type& __p1 = reinterpret_cast<void*&>(__rp1);
    return _ATOMIC_CMPEXCHNG_(this, &__p1, __p2, __m1);
      }

      __return_pointer_type
      fetch_add(ptrdiff_t __d, memory_order __m = memory_order_seq_cst)
      {
    void* __v = _ATOMIC_MODIFY_(this, +=, __d, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }

      __return_pointer_type
      fetch_add(ptrdiff_t __d,
        memory_order __m = memory_order_seq_cst) volatile
      {
    void* __v = _ATOMIC_MODIFY_(this, +=, __d, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }

      __return_pointer_type
      fetch_sub(ptrdiff_t __d, memory_order __m = memory_order_seq_cst)
      {
    void* __v = _ATOMIC_MODIFY_(this, -=, __d, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }

      __return_pointer_type
      fetch_sub(ptrdiff_t __d,
        memory_order __m = memory_order_seq_cst) volatile
      {
    void* __v = _ATOMIC_MODIFY_(this, -=, __d, __m);
    return reinterpret_cast<__return_pointer_type>(__v);
      }
    };

#undef _ATOMIC_LOAD_
#undef _ATOMIC_STORE_
#undef _ATOMIC_MODIFY_
#undef _ATOMIC_CMPEXCHNG_
} // namespace __atomic0

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif