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unittests/ihvtest1/sys_clock.cpp

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//=============================================================================//
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#include <assert.h>
+
+#pragma optimize( "", off )
+
+#pragma pack( push, thing )
+#pragma pack( 4 )
+static long g_cw, g_single_cw, g_highchop_cw, g_full_cw, g_ceil_cw, g_pushed_cw;
+static struct
+{
+	long dummy[8];
+} g_fpenv;
+#pragma pack( pop, thing )
+
+	
+void __declspec ( naked ) MaskExceptions()
+{
+	_asm
+	{
+		fnstenv ds:dword ptr[g_fpenv]
+		or ds:dword ptr[g_fpenv],03Fh
+		fldenv ds:dword ptr[g_fpenv]
+		ret
+	}
+}
+
+void __declspec ( naked ) Sys_SetFPCW()
+{
+	_asm
+	{
+		fnstcw ds:word ptr[g_cw]
+		mov eax,ds:dword ptr[g_cw]
+		and ah,0F0h
+		or ah,003h
+		mov ds:dword ptr[g_full_cw],eax
+		mov ds:dword ptr[g_highchop_cw],eax
+		and ah,0F0h
+		or ah,00Ch
+		mov ds:dword ptr[g_single_cw],eax
+		and ah,0F0h
+		or ah,008h
+		mov ds:dword ptr[g_ceil_cw],eax
+		ret
+	}
+}
+
+void __declspec ( naked ) Sys_PushFPCW_SetHigh()
+{
+	_asm
+	{
+		fnstcw ds:word ptr[g_pushed_cw]
+		fldcw ds:word ptr[g_full_cw]
+		ret
+	}
+}
+
+void __declspec ( naked ) Sys_PopFPCW()
+{
+	_asm
+	{
+		fldcw ds:word ptr[g_pushed_cw]
+		ret
+	}
+}
+
+#pragma optimize( "", on )
+
+//-----------------------------------------------------------------------------
+// Purpose: Implements high precision clock
+// TODO:  Make into an interface?
+//-----------------------------------------------------------------------------
+class CSysClock
+{
+public:
+	// Construction
+							CSysClock( void );
+
+	// Initialization
+	void					Init( void );
+	void					SetStartTime( void );
+
+	// Sample the clock
+	double					GetTime( void );
+
+private:
+	// High performance clock frequency
+	double					m_dClockFrequency;
+	// Current accumulated time
+	double					m_dCurrentTime;
+	// How many bits to shift raw 64 bit sample count by
+	int						m_nTimeSampleShift;
+	// Previous 32 bit sample count
+	unsigned int			m_uiPreviousTime;
+
+	bool					m_bInitialized;
+};
+
+static CSysClock g_Clock;
+
+//-----------------------------------------------------------------------------
+// Purpose: 
+//-----------------------------------------------------------------------------
+CSysClock::CSysClock( void )
+{
+	m_bInitialized = false;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Initialize the clock
+//-----------------------------------------------------------------------------
+void CSysClock::Init( void )
+{
+	BOOL success;
+	LARGE_INTEGER	PerformanceFreq;
+	unsigned int	lowpart, highpart;
+
+	MaskExceptions ();
+	Sys_SetFPCW ();
+
+	// Start clock at zero
+	m_dCurrentTime			= 0.0;
+
+	success = QueryPerformanceFrequency( &PerformanceFreq );
+	assert( success );
+
+	// get 32 out of the 64 time bits such that we have around
+	// 1 microsecond resolution
+	lowpart		= (unsigned int)PerformanceFreq.LowPart;
+	highpart	= (unsigned int)PerformanceFreq.HighPart;
+	
+	m_nTimeSampleShift	= 0;
+
+	while ( highpart || ( lowpart > 2000000.0 ) )
+	{
+		m_nTimeSampleShift++;
+		lowpart >>= 1;
+		lowpart |= (highpart & 1) << 31;
+		highpart >>= 1;
+	}
+	
+	m_dClockFrequency = 1.0 / (double)lowpart;
+
+	// Get initial sample
+	unsigned int		temp;
+	LARGE_INTEGER		PerformanceCount;
+	QueryPerformanceCounter( &PerformanceCount );
+	if ( !m_nTimeSampleShift )
+	{
+		temp = (unsigned int)PerformanceCount.LowPart;
+	}
+	else
+	{
+		// Rotate counter to right by m_nTimeSampleShift places
+		temp = ((unsigned int)PerformanceCount.LowPart >> m_nTimeSampleShift) |
+			   ((unsigned int)PerformanceCount.HighPart << (32 - m_nTimeSampleShift));
+	}
+
+	// Set first time stamp
+	m_uiPreviousTime = temp;
+
+	m_bInitialized = true;
+
+	SetStartTime();
+}
+
+void CSysClock::SetStartTime( void )
+{
+	GetTime();
+
+	m_dCurrentTime = 0.0;
+
+	m_uiPreviousTime = ( unsigned int )m_dCurrentTime;
+}
+
+double CSysClock::GetTime( void )
+{
+	LARGE_INTEGER		PerformanceCount;
+	unsigned int		temp, t2;
+	double				time;
+	
+	if ( !m_bInitialized )
+	{
+		return 0.0;
+	}
+
+	Sys_PushFPCW_SetHigh();
+
+	// Get sample counter
+	QueryPerformanceCounter( &PerformanceCount );
+
+	if ( !m_nTimeSampleShift )
+	{
+		temp = (unsigned int)PerformanceCount.LowPart;
+	}
+	else
+	{
+		// Rotate counter to right by m_nTimeSampleShift places
+		temp = ((unsigned int)PerformanceCount.LowPart >> m_nTimeSampleShift) |
+			   ((unsigned int)PerformanceCount.HighPart << (32 - m_nTimeSampleShift));
+	}
+
+	// check for turnover or backward time
+	if ( ( temp <= m_uiPreviousTime ) && 
+		( ( m_uiPreviousTime - temp ) < 0x10000000) )
+	{
+		m_uiPreviousTime = temp;	// so we can't get stuck
+	}
+	else
+	{
+		// gap in performance clocks
+		t2 = temp - m_uiPreviousTime;
+
+		// Convert to time using frequencey of clock
+		time = (double)t2 * m_dClockFrequency;
+
+		// Remember old time
+		m_uiPreviousTime = temp;
+
+		// Increment clock
+		m_dCurrentTime += time;
+	}
+
+	Sys_PopFPCW();
+
+	// Convert to float
+    return m_dCurrentTime;
+
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Sample the high-precision clock
+// Output : double
+//-----------------------------------------------------------------------------
+double Sys_FloatTime( void )
+{
+	return g_Clock.GetTime();
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Initialize high-precision clock
+//-----------------------------------------------------------------------------
+void Sys_InitFloatTime( void )
+{
+	g_Clock.Init();
+}