//===----------------------------------------------------------------------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#include <__config>

#ifdef _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS

#   define _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS

#endif

#include <memory>

#ifndef _LIBCPP_HAS_NO_THREADS

#  include <mutex>

#  include <thread>

#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)

#    pragma comment(lib, "pthread")

#  endif

#endif

#include "include/atomic_support.h"

_LIBCPP_BEGIN_NAMESPACE_STD

const allocator_arg_t allocator_arg = allocator_arg_t();

bad_weak_ptr::~bad_weak_ptr() noexcept {}

const char*

bad_weak_ptr::what() const noexcept

{

    return "bad_weak_ptr";

}

__shared_count::~__shared_count()

{

}

__shared_weak_count::~__shared_weak_count()

{

}

#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)

void

__shared_count::__add_shared() noexcept

{

    __libcpp_atomic_refcount_increment(__shared_owners_);

}

bool

__shared_count::__release_shared() noexcept

{

    if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1)

    {

        __on_zero_shared();

        return true;

    }

    return false;

}

void

__shared_weak_count::__add_shared() noexcept

{

    __shared_count::__add_shared();

}

void

__shared_weak_count::__add_weak() noexcept

{

    __libcpp_atomic_refcount_increment(__shared_weak_owners_);

}

void

__shared_weak_count::__release_shared() noexcept

{

    if (__shared_count::__release_shared())

        __release_weak();

}

#endif // _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS

void

__shared_weak_count::__release_weak() noexcept

{

    // NOTE: The acquire load here is an optimization of the very

    // common case where a shared pointer is being destructed while

    // having no other contended references.

    //

    // BENEFIT: We avoid expensive atomic stores like XADD and STREX

    // in a common case.  Those instructions are slow and do nasty

    // things to caches.

    //

    // IS THIS SAFE?  Yes.  During weak destruction, if we see that we

    // are the last reference, we know that no-one else is accessing

    // us. If someone were accessing us, then they would be doing so

    // while the last shared / weak_ptr was being destructed, and

    // that's undefined anyway.

    //

    // If we see anything other than a 0, then we have possible

    // contention, and need to use an atomicrmw primitive.

    // The same arguments don't apply for increment, where it is legal

    // (though inadvisable) to share shared_ptr references between

    // threads, and have them all get copied at once.  The argument

    // also doesn't apply for __release_shared, because an outstanding

    // weak_ptr::lock() could read / modify the shared count.

    if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0)

    {

        // no need to do this store, because we are about

        // to destroy everything.

        //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release);

        __on_zero_shared_weak();

    }

    else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1)

        __on_zero_shared_weak();

}

__shared_weak_count*

__shared_weak_count::lock() noexcept

{

    long object_owners = __libcpp_atomic_load(&__shared_owners_);

    while (
object_owners != -122.3M
)

    {

        if (__libcpp_atomic_compare_exchange(&__shared_owners_,

                                             &object_owners,

                                             object_owners+1))

            return this;

    }

    return nullptr;

}

const void*

__shared_weak_count::__get_deleter(const type_info&) const noexcept

{

    return nullptr;

}

#if !defined(_LIBCPP_HAS_NO_THREADS)

static constexpr std::size_t __sp_mut_count = 16;

static constinit __libcpp_mutex_t mut_back[__sp_mut_count] =

{

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER

};

_LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) noexcept

   : __lx(p)

{

}

void

__sp_mut::lock() noexcept

{

    auto m = static_cast<__libcpp_mutex_t*>(__lx);

    unsigned count = 0;

    while (!__libcpp_mutex_trylock(m))

    {

        if (++count > 16)

        {

            __libcpp_mutex_lock(m);

            break;

        }

        this_thread::yield();

    }

}

void

__sp_mut::unlock() noexcept

{

    __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx));

}

__sp_mut&

__get_sp_mut(const void* p)

{

    static constinit __sp_mut muts[__sp_mut_count] = {

        &mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3],

        &mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7],

        &mut_back[ 8], &mut_back[ 9], &mut_back[10], &mut_back[11],

        &mut_back[12], &mut_back[13], &mut_back[14], &mut_back[15]

    };

    return muts[hash<const void*>()(p) & (__sp_mut_count-1)];

}

#endif // !defined(_LIBCPP_HAS_NO_THREADS)

void*

align(size_t alignment, size_t size, void*& ptr, size_t& space)

{

    void* r = nullptr;

    if (size <= space)

    {

        char* p1 = static_cast<char*>(ptr);

        char* p2 = reinterpret_cast<char*>(reinterpret_cast<size_t>(p1 + (alignment - 1)) & -alignment);

        size_t d = static_cast<size_t>(p2 - p1);

        if (d <= space - size)

        {

            r = p2;

            ptr = r;

            space -= d;

        }

    }

    return r;

}

_LIBCPP_END_NAMESPACE_STD