/** 
 * @file llfasttimer.cpp
 * @brief Implementation of the fast timer.
 *
 * $LicenseInfo:firstyear=2004&license=viewergpl$
 * 
 * Copyright (c) 2004-2009, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 * 
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at
 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
 * 
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 * 
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */
#include "linden_common.h"

#include "llfasttimer.h"

#include "llprocessor.h"


#if LL_WINDOWS
#elif LL_LINUX || LL_SOLARIS
#include <sys/time.h>
#include <sched.h>
#elif LL_DARWIN
#include <sys/time.h>
#include "lltimer.h"	// get_clock_count()
#else 
#error "architecture not supported"
#endif

//////////////////////////////////////////////////////////////////////////////
// statics


LLFastTimer::EFastTimerType LLFastTimer::sCurType = LLFastTimer::FTM_OTHER;
int LLFastTimer::sCurDepth = 0;
U64 LLFastTimer::sStart[LLFastTimer::FTM_MAX_DEPTH];
U64 LLFastTimer::sCounter[LLFastTimer::FTM_NUM_TYPES];
U64 LLFastTimer::sCountHistory[LLFastTimer::FTM_HISTORY_NUM][LLFastTimer::FTM_NUM_TYPES];
U64 LLFastTimer::sCountAverage[LLFastTimer::FTM_NUM_TYPES];
U64 LLFastTimer::sCalls[LLFastTimer::FTM_NUM_TYPES];
U64 LLFastTimer::sCallHistory[LLFastTimer::FTM_HISTORY_NUM][LLFastTimer::FTM_NUM_TYPES];
U64 LLFastTimer::sCallAverage[LLFastTimer::FTM_NUM_TYPES];
S32 LLFastTimer::sCurFrameIndex = -1;
S32 LLFastTimer::sLastFrameIndex = -1;
int LLFastTimer::sPauseHistory = 0;
int LLFastTimer::sResetHistory = 0;

F64 LLFastTimer::sCPUClockFrequency = 0.0;

#if LL_LINUX || LL_SOLARIS
U64 LLFastTimer::sClockResolution = 1e9; // Nanosecond resolution
#else 
U64 LLFastTimer::sClockResolution = 1e6; // Microsecond resolution
#endif

//////////////////////////////////////////////////////////////////////////////

//
// CPU clock/other clock frequency and count functions
//

#if LL_WINDOWS

U64 get_cpu_clock_count()
{   U32  hi,lo;

    __asm   
    {
        _emit   0x0f
        _emit   0x31
        mov     lo,eax
        mov     hi,edx
    }

	U64 ret = hi;
	ret *= 4294967296L;
	ret |= lo;
    return ret;
};

#endif // LL_WINDOWS

#if LL_LINUX || LL_SOLARIS
// Try to use the MONOTONIC clock if available, this is a constant time counter
// with nanosecond resolution (but not necessarily accuracy) and attempts are made
// to synchronize this value between cores at kernel start. It should not be effected
// by CPU frequency. If not available use the REALTIME clock, but this may be effected by
// NTP adjustments or other user activity effecting the system time.
U64 get_cpu_clock_count()
{
    struct timespec tp;

#ifdef CLOCK_MONOTONIC
    clock_gettime(CLOCK_MONOTONIC,&tp);
#else
    clock_gettime(CLOCK_REALTIME,&tp);
#endif
    return (tp.tv_sec*LLFastTimer::sClockResolution)+tp.tv_nsec;        
}
#endif // (LL_LINUX || LL_SOLARIS))

#if LL_DARWIN
//
// Mac implementation of CPU clock
//
// Just use gettimeofday implementation for now

U64 get_cpu_clock_count()
{
	return get_clock_count();
}
#endif

//////////////////////////////////////////////////////////////////////////////

//static
#if LL_DARWIN || LL_LINUX || LL_SOLARIS
// Both Linux and Mac use gettimeofday for accurate time
U64 LLFastTimer::countsPerSecond()
{
	return sClockResolution; // microseconds, so 1 Mhz.
}
#else 
U64 LLFastTimer::countsPerSecond()
{
	if (!sCPUClockFrequency)
	{
		CProcessor proc;
		sCPUClockFrequency = proc.GetCPUFrequency(50);
	}
	return U64(sCPUClockFrequency);
}
#endif

void LLFastTimer::reset()
{
	countsPerSecond(); // good place to calculate clock frequency
	
	if (sCurDepth != 0)
	{
		llerrs << "LLFastTimer::Reset() when sCurDepth != 0" << llendl;
	}
	if (sPauseHistory)
	{
		sResetHistory = 1;
	}
	else if (sResetHistory)
	{
		sCurFrameIndex = -1;
		sResetHistory = 0;
	}
	else if (sCurFrameIndex >= 0)
	{
		int hidx = sCurFrameIndex % FTM_HISTORY_NUM;
		for (S32 i=0; i<FTM_NUM_TYPES; i++)
		{
			sCountHistory[hidx][i] = sCounter[i];
			sCountAverage[i] = (sCountAverage[i]*sCurFrameIndex + sCounter[i]) / (sCurFrameIndex+1);
			sCallHistory[hidx][i] = sCalls[i];
			sCallAverage[i] = (sCallAverage[i]*sCurFrameIndex + sCalls[i]) / (sCurFrameIndex+1);
		}
		sLastFrameIndex = sCurFrameIndex;
	}
	else
	{
		for (S32 i=0; i<FTM_NUM_TYPES; i++)
		{
			sCountAverage[i] = 0;
			sCallAverage[i] = 0;
		}
	}
	
	sCurFrameIndex++;
	
	for (S32 i=0; i<FTM_NUM_TYPES; i++)
	{
		sCounter[i] = 0;
		sCalls[i] = 0;
	}
	sCurDepth = 0;
}

//////////////////////////////////////////////////////////////////////////////