Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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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();
}