// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef rr_Thread_hpp
#define rr_Thread_hpp

#if defined(_WIN32)
#	ifndef WIN32_LEAN_AND_MEAN
#		define WIN32_LEAN_AND_MEAN
#	endif
#	include <windows.h>
#	include <intrin.h>
#else
#	include <pthread.h>
#	include <sched.h>
#	include <unistd.h>
#	define TLS_OUT_OF_INDEXES (pthread_key_t)(~0)
#endif

#include <stdlib.h>

#if defined(__clang__)
#	if __has_include(<atomic>)  // clang has an explicit check for the availability of atomic
#		define USE_STD_ATOMIC 1
#	endif
// atomic is available in C++11 or newer, and in Visual Studio 2012 or newer
#elif(defined(_MSC_VER) && (_MSC_VER >= 1700)) || (__cplusplus >= 201103L)
#	define USE_STD_ATOMIC 1
#endif

#if USE_STD_ATOMIC
#	include <atomic>
#endif

namespace rr {

class Event;

class Thread
{
public:
	Thread(void (*threadFunction)(void *parameters), void *parameters);

	~Thread();

	void join();

	static void yield();
	static void sleep(int milliseconds);

#if defined(_WIN32)
	typedef DWORD LocalStorageKey;
#else
	typedef pthread_key_t LocalStorageKey;
#endif

	static LocalStorageKey allocateLocalStorageKey(void (*destructor)(void *storage) = free);
	static void freeLocalStorageKey(LocalStorageKey key);
	static void *allocateLocalStorage(LocalStorageKey key, size_t size);
	static void *getLocalStorage(LocalStorageKey key);
	static void freeLocalStorage(LocalStorageKey key);

private:
	struct Entry
	{
		void (*const threadFunction)(void *parameters);
		void *threadParameters;
		Event *init;
	};

#if defined(_WIN32)
	static unsigned long __stdcall startFunction(void *parameters);
	HANDLE handle;
#else
	static void *startFunction(void *parameters);
	pthread_t handle;
#endif

	bool hasJoined = false;
};

class Event
{
	friend class Thread;

public:
	Event();

	~Event();

	void signal();
	void wait();

private:
#if defined(_WIN32)
	HANDLE handle;
#else
	pthread_cond_t handle;
	pthread_mutex_t mutex;
	volatile bool signaled;
#endif
};

#if PERF_PROFILE
int64_t atomicExchange(int64_t volatile *target, int64_t value);
int atomicExchange(int volatile *target, int value);
#endif

int atomicIncrement(int volatile *value);
int atomicDecrement(int volatile *value);
int atomicAdd(int volatile *target, int value);
void nop();

}  // namespace rr

/* Inline implementation */

namespace rr {

inline void Thread::yield()
{
#if defined(_WIN32)
	Sleep(0);
#elif defined(__APPLE__)
	pthread_yield_np();
#else
	sched_yield();
#endif
}

inline void Thread::sleep(int milliseconds)
{
#if defined(_WIN32)
	Sleep(milliseconds);
#else
	usleep(1000 * milliseconds);
#endif
}

inline Thread::LocalStorageKey Thread::allocateLocalStorageKey(void (*destructor)(void *storage))
{
#if defined(_WIN32)
	return TlsAlloc();
#else
	LocalStorageKey key;
	pthread_key_create(&key, destructor);
	return key;
#endif
}

inline void Thread::freeLocalStorageKey(LocalStorageKey key)
{
#if defined(_WIN32)
	TlsFree(key);
#else
	pthread_key_delete(key);  // Using an invalid key is an error but not undefined behavior.
#endif
}

inline void *Thread::allocateLocalStorage(LocalStorageKey key, size_t size)
{
	if(key == TLS_OUT_OF_INDEXES)
	{
		return nullptr;
	}

	freeLocalStorage(key);

	void *storage = malloc(size);

#if defined(_WIN32)
	TlsSetValue(key, storage);
#else
	pthread_setspecific(key, storage);
#endif

	return storage;
}

inline void *Thread::getLocalStorage(LocalStorageKey key)
{
#if defined(_WIN32)
	return TlsGetValue(key);
#else
	if(key == TLS_OUT_OF_INDEXES)  // Avoid undefined behavior.
	{
		return nullptr;
	}

	return pthread_getspecific(key);
#endif
}

inline void Thread::freeLocalStorage(LocalStorageKey key)
{
	free(getLocalStorage(key));

#if defined(_WIN32)
	TlsSetValue(key, nullptr);
#else
	pthread_setspecific(key, nullptr);
#endif
}

inline void Event::signal()
{
#if defined(_WIN32)
	SetEvent(handle);
#else
	pthread_mutex_lock(&mutex);
	signaled = true;
	pthread_cond_signal(&handle);
	pthread_mutex_unlock(&mutex);
#endif
}

inline void Event::wait()
{
#if defined(_WIN32)
	WaitForSingleObject(handle, INFINITE);
#else
	pthread_mutex_lock(&mutex);
	while(!signaled) pthread_cond_wait(&handle, &mutex);
	signaled = false;
	pthread_mutex_unlock(&mutex);
#endif
}

#if PERF_PROFILE
inline int64_t atomicExchange(volatile int64_t *target, int64_t value)
{
#	if defined(_WIN32)
	return InterlockedExchange64(target, value);
#	else
	int ret;
	__asm__ __volatile__("lock; xchg8 %x0,(%x1)"
	                     : "=r"(ret)
	                     : "r"(target), "0"(value)
	                     : "memory");
	return ret;
#	endif
}

inline int atomicExchange(volatile int *target, int value)
{
#	if defined(_WIN32)
	return InterlockedExchange((volatile long *)target, (long)value);
#	else
	int ret;
	__asm__ __volatile__("lock; xchgl %x0,(%x1)"
	                     : "=r"(ret)
	                     : "r"(target), "0"(value)
	                     : "memory");
	return ret;
#	endif
}
#endif

inline int atomicIncrement(volatile int *value)
{
#if defined(_WIN32)
	return InterlockedIncrement((volatile long *)value);
#else
	return __sync_add_and_fetch(value, 1);
#endif
}

inline int atomicDecrement(volatile int *value)
{
#if defined(_WIN32)
	return InterlockedDecrement((volatile long *)value);
#else
	return __sync_sub_and_fetch(value, 1);
#endif
}

inline int atomicAdd(volatile int *target, int value)
{
#if defined(_WIN32)
	return InterlockedExchangeAdd((volatile long *)target, value) + value;
#else
	return __sync_add_and_fetch(target, value);
#endif
}

inline void nop()
{
#if defined(_WIN32)
	__nop();
#else
	__asm__ __volatile__("nop");
#endif
}

#if USE_STD_ATOMIC
class AtomicInt
{
public:
	AtomicInt()
	    : ai()
	{}
	AtomicInt(int i)
	    : ai(i)
	{}

	inline operator int() const { return ai.load(std::memory_order_acquire); }
	inline void operator=(const AtomicInt &i) { ai.store(i.ai.load(std::memory_order_acquire), std::memory_order_release); }
	inline void operator=(int i) { ai.store(i, std::memory_order_release); }
	inline void operator--() { ai.fetch_sub(1, std::memory_order_acq_rel); }
	inline void operator++() { ai.fetch_add(1, std::memory_order_acq_rel); }
	inline int operator--(int) { return ai.fetch_sub(1, std::memory_order_acq_rel) - 1; }
	inline int operator++(int) { return ai.fetch_add(1, std::memory_order_acq_rel) + 1; }
	inline void operator-=(int i) { ai.fetch_sub(i, std::memory_order_acq_rel); }
	inline void operator+=(int i) { ai.fetch_add(i, std::memory_order_acq_rel); }

private:
	std::atomic<int> ai;
};
#else
class AtomicInt
{
public:
	AtomicInt() {}
	AtomicInt(int i)
	    : vi(i)
	{}

	inline operator int() const { return vi; }  // Note: this isn't a guaranteed atomic operation
	inline void operator=(const AtomicInt &i) { atomicExchange(&vi, i.vi); }
	inline void operator=(int i) { atomicExchange(&vi, i); }
	inline void operator--() { atomicDecrement(&vi); }
	inline void operator++() { atomicIncrement(&vi); }
	inline int operator--(int) { return atomicDecrement(&vi); }
	inline int operator++(int) { return atomicIncrement(&vi); }
	inline void operator-=(int i) { atomicAdd(&vi, -i); }
	inline void operator+=(int i) { atomicAdd(&vi, i); }

private:
	volatile int vi;
};
#endif

}  // namespace rr

#endif  // rr_Thread_hpp