text: /*
   * Copyright © 2007  Chris Wilson
   * Copyright © 2009,2010  Red Hat, Inc.
   * Copyright © 2011,2012  Google, Inc.
   *
   *  This is part of HarfBuzz, a text shaping library.
   *
   * Permission is hereby granted, without written agreement and without
   * license or royalty fees, to use, copy, modify, and distribute this
   * software and its documentation for any purpose, provided that the
   * above copyright notice and the following two paragraphs appear in
   * all copies of this software.
   *
   * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
   * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
   * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
   * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
   * DAMAGE.
   *
   * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
   * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
   * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
   * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
   *
   * Contributor(s):
   *	Chris Wilson <chris@chris-wilson.co.uk>
   * Red Hat Author(s): Behdad Esfahbod
   * Google Author(s): Behdad Esfahbod
   */
  
  #ifndef HB_ATOMIC_HH
  #define HB_ATOMIC_HH
  
  #include "hb.hh"
  #include "hb-meta.hh"
  
  
  /*
   * Atomic integers and pointers.
   */
  
  
  /* We need external help for these */
  
  #if defined(hb_atomic_int_impl_add) \
   && defined(hb_atomic_ptr_impl_get) \
   && defined(hb_atomic_ptr_impl_cmpexch)
  
  /* Defined externally, i.e. in config.h. */
  
  
  #elif !defined(HB_NO_MT) && defined(__ATOMIC_ACQUIRE)
  
  /* C++11-style GCC primitives. We prefer these as they don't require linking to libstdc++ / libc++. */
  
  #define _hb_memory_barrier()			__sync_synchronize ()
  
  #define hb_atomic_int_impl_add(AI, V)		__atomic_fetch_add ((AI), (V), __ATOMIC_ACQ_REL)
  #define hb_atomic_int_impl_set_relaxed(AI, V)	__atomic_store_n ((AI), (V), __ATOMIC_RELAXED)
  #define hb_atomic_int_impl_set(AI, V)		__atomic_store_n ((AI), (V), __ATOMIC_RELEASE)
  #define hb_atomic_int_impl_get_relaxed(AI)	__atomic_load_n ((AI), __ATOMIC_RELAXED)
  #define hb_atomic_int_impl_get(AI)		__atomic_load_n ((AI), __ATOMIC_ACQUIRE)
  
  #define hb_atomic_ptr_impl_set_relaxed(P, V)	__atomic_store_n ((P), (V), __ATOMIC_RELAXED)
  #define hb_atomic_ptr_impl_get_relaxed(P)	__atomic_load_n ((P), __ATOMIC_RELAXED)
  #define hb_atomic_ptr_impl_get(P)		__atomic_load_n ((P), __ATOMIC_ACQUIRE)
  static inline bool
  _hb_atomic_ptr_impl_cmplexch (const void **P, const void *O_, const void *N)
  {
    const void *O = O_; // Need lvalue
    return __atomic_compare_exchange_n ((void **) P, (void **) &O, (void *) N, true, __ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
  }
  #define hb_atomic_ptr_impl_cmpexch(P,O,N)	_hb_atomic_ptr_impl_cmplexch ((const void **) (P), (O), (N))
  
  
  #elif !defined(HB_NO_MT)
  
  /* C++11 atomics. */
  
  #include <atomic>
  
  #define _hb_memory_barrier()			std::atomic_thread_fence(std::memory_order_ack_rel)
  #define _hb_memory_r_barrier()			std::atomic_thread_fence(std::memory_order_acquire)
  #define _hb_memory_w_barrier()			std::atomic_thread_fence(std::memory_order_release)
  
  #define hb_atomic_int_impl_add(AI, V)		(reinterpret_cast<std::atomic<int> *> (AI)->fetch_add ((V), std::memory_order_acq_rel))
  #define hb_atomic_int_impl_set_relaxed(AI, V)	(reinterpret_cast<std::atomic<int> *> (AI)->store ((V), std::memory_order_relaxed))
  #define hb_atomic_int_impl_set(AI, V)		(reinterpret_cast<std::atomic<int> *> (AI)->store ((V), std::memory_order_release))
  #define hb_atomic_int_impl_get_relaxed(AI)	(reinterpret_cast<std::atomic<int> const *> (AI)->load (std::memory_order_relaxed))
  #define hb_atomic_int_impl_get(AI)		(reinterpret_cast<std::atomic<int> const *> (AI)->load (std::memory_order_acquire))
  
  #define hb_atomic_ptr_impl_set_relaxed(P, V)	(reinterpret_cast<std::atomic<void*> *> (P)->store ((V), std::memory_order_relaxed))
  #define hb_atomic_ptr_impl_get_relaxed(P)	(reinterpret_cast<std::atomic<void*> const *> (P)->load (std::memory_order_relaxed))
  #define hb_atomic_ptr_impl_get(P)		(reinterpret_cast<std::atomic<void*> *> (P)->load (std::memory_order_acquire))
  static inline bool
  _hb_atomic_ptr_impl_cmplexch (const void **P, const void *O_, const void *N)
  {
    const void *O = O_; // Need lvalue
    return reinterpret_cast<std::atomic<const void*> *> (P)->compare_exchange_weak (O, N, std::memory_order_acq_rel, std::memory_order_relaxed);
  }
  #define hb_atomic_ptr_impl_cmpexch(P,O,N)	_hb_atomic_ptr_impl_cmplexch ((const void **) (P), (O), (N))
  
  
  #elif defined(HB_NO_MT)
  
  #define hb_atomic_int_impl_add(AI, V)		((*(AI) += (V)) - (V))
  
  #define _hb_memory_barrier()			do {} while (0)
  
  #define hb_atomic_ptr_impl_cmpexch(P,O,N)	(* (void **) (P) == (void *) (O) ? (* (void **) (P) = (void *) (N), true) : false)
  
  
  #else
  
  #error "Could not find any system to define atomic_int macros."
  #error "Check hb-atomic.hh for possible resolutions."
  
  #endif
  
  
  #ifndef _hb_memory_r_barrier
  #define _hb_memory_r_barrier()			_hb_memory_barrier ()
  #endif
  #ifndef _hb_memory_w_barrier
  #define _hb_memory_w_barrier()			_hb_memory_barrier ()
  #endif
  #ifndef hb_atomic_int_impl_set_relaxed
  #define hb_atomic_int_impl_set_relaxed(AI, V)	(*(AI) = (V))
  #endif
  #ifndef hb_atomic_int_impl_get_relaxed
  #define hb_atomic_int_impl_get_relaxed(AI)	(*(AI))
  #endif
  
  #ifndef hb_atomic_ptr_impl_set_relaxed
  #define hb_atomic_ptr_impl_set_relaxed(P, V)	(*(P) = (V))
  #endif
  #ifndef hb_atomic_ptr_impl_get_relaxed
  #define hb_atomic_ptr_impl_get_relaxed(P)	(*(P))
  #endif
  #ifndef hb_atomic_int_impl_set
  inline void hb_atomic_int_impl_set (int *AI, int v)	{ _hb_memory_w_barrier (); *AI = v; }
  #endif
  #ifndef hb_atomic_int_impl_get
  inline int hb_atomic_int_impl_get (const int *AI)	{ int v = *AI; _hb_memory_r_barrier (); return v; }
  #endif
  #ifndef hb_atomic_ptr_impl_get
  inline void *hb_atomic_ptr_impl_get (void ** const P)	{ void *v = *P; _hb_memory_r_barrier (); return v; }
  #endif
  
  
  struct hb_atomic_int_t
  {
    hb_atomic_int_t () = default;
    constexpr hb_atomic_int_t (int v) : v (v) {}
  
    void set_relaxed (int v_) { hb_atomic_int_impl_set_relaxed (&v, v_); }
    void set (int v_) { hb_atomic_int_impl_set (&v, v_); }
    int get_relaxed () const { return hb_atomic_int_impl_get_relaxed (&v); }
    int get () const { return hb_atomic_int_impl_get (&v); }
    int inc () { return hb_atomic_int_impl_add (&v,  1); }
    int dec () { return hb_atomic_int_impl_add (&v, -1); }
  
    int v = 0;
  };
  
  template <typename P>
  struct hb_atomic_ptr_t
  {
    typedef hb_remove_pointer<P> T;
  
    hb_atomic_ptr_t () = default;
    constexpr hb_atomic_ptr_t (T* v) : v (v) {}
  
    void init (T* v_ = nullptr) { set_relaxed (v_); }
    void set_relaxed (T* v_) { hb_atomic_ptr_impl_set_relaxed (&v, v_); }
    T *get_relaxed () const { return (T *) hb_atomic_ptr_impl_get_relaxed (&v); }
    T *get () const { return (T *) hb_atomic_ptr_impl_get ((void **) &v); }
    bool cmpexch (const T *old, T *new_) const { return hb_atomic_ptr_impl_cmpexch ((void **) &v, (void *) old, (void *) new_); }
  
    T * operator -> () const                    { return get (); }
    template <typename C> operator C * () const { return get (); }
  
    T *v = nullptr;
  };
  
  
  #endif /* HB_ATOMIC_HH */
  