/*
* Copyright (c) 2011 Erin Catto http://box2d.org
* Copyright (c) 2014 Google, Inc.
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

#include <Box2D/Common/b2Timer.h>

#if defined(_WIN32)

float64 b2Timer::s_invFrequency = 0.0f;

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

typedef BOOL (WINAPI *SystemGetTimeFunc)(_Out_ LARGE_INTEGER *lpFrequency);
SystemGetTimeFunc systemGetTimeFunc = ::QueryPerformanceCounter;
SystemGetTimeFunc systemGetFreqFunc = ::QueryPerformanceFrequency;

int64 b2Timer::GetTicks()
{
	LARGE_INTEGER largeInteger;
	systemGetTimeFunc(&largeInteger);
	return largeInteger.QuadPart;
}

b2Timer::b2Timer()
{
	LARGE_INTEGER largeInteger;

	if (s_invFrequency == 0.0f)
	{
		systemGetFreqFunc(&largeInteger);
		s_invFrequency = float64(largeInteger.QuadPart);
		if (s_invFrequency > 0.0f)
		{
			s_invFrequency = 1000.0f / s_invFrequency;
		}
	}

	m_start = GetTicks();
}

void b2Timer::Reset()
{
	m_start = GetTicks();
}

float32 b2Timer::GetMilliseconds() const
{
	int64 elapsed = GetTicks() - m_start;
	return (float32)(s_invFrequency * elapsed);
}

#elif defined(__linux__) || defined (__APPLE__)

#include <sys/time.h>
#include <time.h>

// systemGetTimeFunc is defined with external linkage to allow unit
// test to mock out the system time function

#if defined(__linux__)

typedef int (*SystemGetTimeFunc)(clockid_t clk_id, struct timespec *tp);
SystemGetTimeFunc systemGetTimeFunc = ::clock_gettime;

#elif defined(__APPLE__)

typedef int (*SystemGetTimeFunc)(struct timeval * tp, void * tzp);
SystemGetTimeFunc systemGetTimeFunc = ::gettimeofday;

#endif

int64 b2Timer::GetTicks()
{
	static const int NSEC_PER_SEC = 1000000000;

#ifdef __linux__
	timespec ts;
	systemGetTimeFunc(CLOCK_MONOTONIC,&ts);
	return ((int64)ts.tv_sec) * NSEC_PER_SEC + ts.tv_nsec;
#else
	timeval t;
	systemGetTimeFunc(&t, 0);
	return ((int64)t.tv_sec) * NSEC_PER_SEC + t.tv_usec * 1000;
#endif
}

b2Timer::b2Timer()
{
	Reset();
}

void b2Timer::Reset()
{
	m_start = GetTicks();
}

float32 b2Timer::GetMilliseconds() const
{
	static const float32 kTicksToMs = 0.000001f;
	return kTicksToMs * (float32)(GetTicks() - m_start);
}

#else

b2Timer::b2Timer()
{
}

void b2Timer::Reset()
{
}

float32 b2Timer::GetMilliseconds() const
{
	return 0.0f;
}

#endif