--- /dev/null
+//$$CDS-header$$
+
+#ifndef __CDS_DETAILS_MARKED_PTR_H
+#define __CDS_DETAILS_MARKED_PTR_H
+
+#include <cds/cxx11_atomic.h>
+
+namespace cds {
+ namespace details {
+
+ /// Marked pointer
+ /**
+ On the modern architectures, the default data alignment is 4 (for 32bit) or 8 byte for 64bit.
+ Therefore, the least 2 or 3 bits of the pointer is always zero and can
+ be used as a bitfield to store logical flags. This trick is widely used in
+ lock-free programming to operate with the pointer and its flags atomically.
+
+ Template parameters:
+ - T - type of pointer
+ - Bitmask - bitmask of least unused bits
+ */
+ template <typename T, int Bitmask>
+ class marked_ptr
+ {
+ T * m_ptr ; ///< pointer and its mark bits
+
+ public:
+ typedef T value_type ; ///< type of value the class points to
+ typedef T * pointer_type ; ///< type of pointer
+ static CDS_CONSTEXPR_CONST uintptr_t bitmask = Bitmask ; ///< bitfield bitmask
+ static CDS_CONSTEXPR_CONST uintptr_t pointer_bitmask = ~bitmask ; ///< pointer bitmask
+
+ public:
+ /// Constructs null marked pointer. The flag is cleared.
+ CDS_CONSTEXPR marked_ptr() CDS_NOEXCEPT
+ : m_ptr( null_ptr<pointer_type>() )
+ {}
+
+ /// Constructs marked pointer with \p ptr value. The least bit(s) of \p ptr is the flag.
+ CDS_CONSTEXPR explicit marked_ptr( value_type * ptr ) CDS_NOEXCEPT
+ : m_ptr( ptr )
+ {}
+
+ /// Constructs marked pointer with \p ptr value and \p nMask flag.
+ /**
+ The \p nMask argument defines the OR-bits
+ */
+ marked_ptr( value_type * ptr, int nMask ) CDS_NOEXCEPT
+ : m_ptr( ptr )
+ {
+ assert( bits() == 0 );
+ *this |= nMask;
+ }
+
+# ifdef CDS_CXX11_EXPLICITLY_DEFAULTED_FUNCTION_SUPPORT
+ /// Copy constructor
+ marked_ptr( marked_ptr const& src ) CDS_NOEXCEPT_DEFAULTED = default;
+ /// Copy-assignment operator
+ marked_ptr& operator =( marked_ptr const& p ) CDS_NOEXCEPT_DEFAULTED = default;
+# if defined(CDS_MOVE_SEMANTICS_SUPPORT) && !defined(CDS_DISABLE_DEFAULT_MOVE_CTOR)
+ //@cond
+ marked_ptr( marked_ptr&& src ) CDS_NOEXCEPT_DEFAULTED = default;
+ marked_ptr& operator =( marked_ptr&& p ) CDS_NOEXCEPT_DEFAULTED = default;
+ //@endcond
+# endif
+# else
+ /// Copy constructor
+ marked_ptr( marked_ptr const& src ) CDS_NOEXCEPT
+ : m_ptr( src.m_ptr )
+ {}
+
+ /// Copy-assignment operator
+ marked_ptr& operator =( marked_ptr const& p ) CDS_NOEXCEPT
+ {
+ m_ptr = p.m_ptr;
+ return *this;
+ }
+# endif
+
+ //TODO: make move ctor
+
+ private:
+ //@cond
+ static uintptr_t to_int( value_type * p ) CDS_NOEXCEPT
+ {
+ return reinterpret_cast<uintptr_t>( p );
+ }
+
+ static value_type * to_ptr( uintptr_t n ) CDS_NOEXCEPT
+ {
+ return reinterpret_cast< value_type *>( n );
+ }
+
+ uintptr_t to_int() const CDS_NOEXCEPT
+ {
+ return to_int( m_ptr );
+ }
+ //@endcond
+
+ public:
+ /// Returns the pointer without mark bits (real pointer) const version
+ value_type * ptr() const CDS_NOEXCEPT
+ {
+ return to_ptr( to_int() & ~bitmask );
+ }
+
+ /// Returns the pointer and bits together
+ value_type * all() const CDS_NOEXCEPT
+ {
+ return m_ptr;
+ }
+
+ /// Returns the least bits of pointer according to \p Bitmask template argument of the class
+ uintptr_t bits() const CDS_NOEXCEPT
+ {
+ return to_int() & bitmask;
+ }
+
+ /// Analogue for \ref ptr
+ value_type * operator ->() const CDS_NOEXCEPT
+ {
+ return ptr();
+ }
+
+ /// Assignment operator sets markup bits to zero
+ marked_ptr operator =( T * p ) CDS_NOEXCEPT
+ {
+ m_ptr = p;
+ return *this;
+ }
+
+ /// Set LSB bits as <tt>bits() | nBits</tt>
+ marked_ptr& operator |=( int nBits ) CDS_NOEXCEPT
+ {
+ assert( (nBits & pointer_bitmask) == 0 );
+ m_ptr = to_ptr( to_int() | nBits );
+ return *this;
+ }
+
+ /// Set LSB bits as <tt>bits() & nBits</tt>
+ marked_ptr& operator &=( int nBits ) CDS_NOEXCEPT
+ {
+ assert( (nBits & pointer_bitmask) == 0 );
+ m_ptr = to_ptr( to_int() & (pointer_bitmask | nBits) );
+ return *this;
+ }
+
+ /// Set LSB bits as <tt>bits() ^ nBits</tt>
+ marked_ptr& operator ^=( int nBits ) CDS_NOEXCEPT
+ {
+ assert( (nBits & pointer_bitmask) == 0 );
+ m_ptr = to_ptr( to_int() ^ nBits );
+ return *this;
+ }
+
+ /// Returns <tt>p |= nBits</tt>
+ friend marked_ptr operator |( marked_ptr p, int nBits) CDS_NOEXCEPT
+ {
+ p |= nBits;
+ return p;
+ }
+
+ /// Returns <tt>p |= nBits</tt>
+ friend marked_ptr operator |( int nBits, marked_ptr p ) CDS_NOEXCEPT
+ {
+ p |= nBits;
+ return p;
+ }
+
+ /// Returns <tt>p &= nBits</tt>
+ friend marked_ptr operator &( marked_ptr p, int nBits) CDS_NOEXCEPT
+ {
+ p &= nBits;
+ return p;
+ }
+
+ /// Returns <tt>p &= nBits</tt>
+ friend marked_ptr operator &( int nBits, marked_ptr p ) CDS_NOEXCEPT
+ {
+ p &= nBits;
+ return p;
+ }
+
+ /// Returns <tt>p ^= nBits</tt>
+ friend marked_ptr operator ^( marked_ptr p, int nBits) CDS_NOEXCEPT
+ {
+ p ^= nBits;
+ return p;
+ }
+ /// Returns <tt>p ^= nBits</tt>
+ friend marked_ptr operator ^( int nBits, marked_ptr p ) CDS_NOEXCEPT
+ {
+ p ^= nBits;
+ return p;
+ }
+
+ /// Inverts LSBs of pointer \p p
+ friend marked_ptr operator ~( marked_ptr p ) CDS_NOEXCEPT
+ {
+ return p ^ marked_ptr::bitmask;
+ }
+
+
+ /// Comparing two marked pointer including its mark bits
+ friend bool operator ==( marked_ptr p1, marked_ptr p2 ) CDS_NOEXCEPT
+ {
+ return p1.all() == p2.all();
+ }
+
+ /// Comparing marked pointer and raw pointer, mark bits of \p p1 is ignored
+ friend bool operator ==( marked_ptr p1, value_type const * p2 ) CDS_NOEXCEPT
+ {
+ return p1.ptr() == p2;
+ }
+
+ /// Comparing marked pointer and raw pointer, mark bits of \p p2 is ignored
+ friend bool operator ==( value_type const * p1, marked_ptr p2 ) CDS_NOEXCEPT
+ {
+ return p1 == p2.ptr();
+ }
+
+ /// Comparing two marked pointer including its mark bits
+ friend bool operator !=( marked_ptr p1, marked_ptr p2 ) CDS_NOEXCEPT
+ {
+ return p1.all() != p2.all();
+ }
+
+ /// Comparing marked pointer and raw pointer, mark bits of \p p1 is ignored
+ friend bool operator !=( marked_ptr p1, value_type const * p2 ) CDS_NOEXCEPT
+ {
+ return p1.ptr() != p2;
+ }
+
+ /// Comparing marked pointer and raw pointer, mark bits of \p p2 is ignored
+ friend bool operator !=( value_type const * p1, marked_ptr p2 ) CDS_NOEXCEPT
+ {
+ return p1 != p2.ptr();
+ }
+
+ //@cond
+ /// atomic< marked_ptr< T, Bitmask > > support
+ T *& impl_ref() CDS_NOEXCEPT
+ {
+ return m_ptr;
+ }
+ //@endcond
+ };
+ } // namespace details
+
+} // namespace cds
+
+//@cond
+CDS_CXX11_ATOMIC_BEGIN_NAMESPACE
+
+ template <typename T, int Bitmask >
+ class atomic< cds::details::marked_ptr<T, Bitmask> >
+ {
+ private:
+ typedef cds::details::marked_ptr<T, Bitmask> marked_ptr;
+ typedef CDS_ATOMIC::atomic<T *> atomic_impl;
+
+ atomic_impl m_atomic;
+ public:
+ bool is_lock_free() const volatile CDS_NOEXCEPT
+ {
+ return m_atomic.is_lock_free();
+ }
+ bool is_lock_free() const CDS_NOEXCEPT
+ {
+ return m_atomic.is_lock_free();
+ }
+
+ void store(marked_ptr val, memory_order order = memory_order_seq_cst) volatile CDS_NOEXCEPT
+ {
+ m_atomic.store( val.all(), order );
+ }
+ void store(marked_ptr val, memory_order order = memory_order_seq_cst) CDS_NOEXCEPT
+ {
+ m_atomic.store( val.all(), order );
+ }
+
+ marked_ptr load(memory_order order = memory_order_seq_cst) const volatile CDS_NOEXCEPT
+ {
+ return marked_ptr( m_atomic.load( order ));
+ }
+ marked_ptr load(memory_order order = memory_order_seq_cst) const CDS_NOEXCEPT
+ {
+ return marked_ptr( m_atomic.load( order ));
+ }
+
+ operator marked_ptr() const volatile CDS_NOEXCEPT
+ {
+ return load();
+ }
+ operator marked_ptr() const CDS_NOEXCEPT
+ {
+ return load();
+ }
+
+ marked_ptr exchange(marked_ptr val, memory_order order = memory_order_seq_cst) volatile CDS_NOEXCEPT
+ {
+ return marked_ptr( m_atomic.exchange( val.all(), order ));
+ }
+ marked_ptr exchange(marked_ptr val, memory_order order = memory_order_seq_cst) CDS_NOEXCEPT
+ {
+ return marked_ptr( m_atomic.exchange( val.all(), order ));
+ }
+
+ bool compare_exchange_weak(marked_ptr& expected, marked_ptr desired, memory_order success_order, memory_order failure_order) volatile CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_weak( expected.impl_ref(), desired.all(), success_order, failure_order );
+ }
+ bool compare_exchange_weak(marked_ptr& expected, marked_ptr desired, memory_order success_order, memory_order failure_order) CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_weak( expected.impl_ref(), desired.all(), success_order, failure_order );
+ }
+ bool compare_exchange_strong(marked_ptr& expected, marked_ptr desired, memory_order success_order, memory_order failure_order) volatile CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_strong( expected.impl_ref(), desired.all(), success_order, failure_order );
+ }
+ bool compare_exchange_strong(marked_ptr& expected, marked_ptr desired, memory_order success_order, memory_order failure_order) CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_strong( expected.impl_ref(), desired.all(), success_order, failure_order );
+ }
+ bool compare_exchange_weak(marked_ptr& expected, marked_ptr desired, memory_order success_order = memory_order_seq_cst) volatile CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_weak( expected.impl_ref(), desired.all(), success_order );
+ }
+ bool compare_exchange_weak(marked_ptr& expected, marked_ptr desired, memory_order success_order = memory_order_seq_cst) CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_weak( expected.impl_ref(), desired.all(), success_order );
+ }
+ bool compare_exchange_strong(marked_ptr& expected, marked_ptr desired, memory_order success_order = memory_order_seq_cst) volatile CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_strong( expected.impl_ref(), desired.all(), success_order );
+ }
+ bool compare_exchange_strong(marked_ptr& expected, marked_ptr desired, memory_order success_order = memory_order_seq_cst) CDS_NOEXCEPT
+ {
+ return m_atomic.compare_exchange_strong( expected.impl_ref(), desired.all(), success_order );
+ }
+
+ CDS_CONSTEXPR atomic() CDS_NOEXCEPT
+ : m_atomic( cds::null_ptr<T *>() )
+ {}
+
+ CDS_CONSTEXPR explicit atomic(marked_ptr val) CDS_NOEXCEPT
+ : m_atomic( val.all() )
+ {}
+ CDS_CONSTEXPR explicit atomic(T * p) CDS_NOEXCEPT
+ : m_atomic( p )
+ {}
+
+# ifdef CDS_CXX11_DELETE_DEFINITION_SUPPORT
+ atomic(const atomic&) = delete;
+ atomic& operator=(const atomic&) = delete;
+ atomic& operator=(const atomic&) volatile = delete;
+# endif
+
+ marked_ptr operator=(marked_ptr val) volatile CDS_NOEXCEPT
+ {
+ store( val );
+ return val;
+ }
+ marked_ptr operator=(marked_ptr val) CDS_NOEXCEPT
+ {
+ store( val );
+ return val;
+ }
+ };
+
+CDS_CXX11_ATOMIC_END_NAMESPACE
+//@endcond
+
+#endif // #ifndef __CDS_DETAILS_MARKED_PTR_H
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