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tier0/fasttimer.cpp

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//=============================================================================//
+
+#include "pch_tier0.h"
+
+#include <stdio.h>
+#include "tier0/fasttimer.h"
+
+// g_dwClockSpeed is only exported for backwards compatibility.
+PLATFORM_INTERFACE unsigned long g_dwClockSpeed;
+
+uint64 g_ClockSpeed;	// Clocks/sec
+// Storing CPU clock speed in a 32-bit variable is dangerous and can already overflow
+// on some CPUs. This variable is deprecated.
+unsigned long g_dwClockSpeed;
+#if defined( _X360 ) && defined( _CERT )
+unsigned long g_dwFakeFastCounter;
+#endif
+double g_ClockSpeedMicrosecondsMultiplier;
+double g_ClockSpeedMillisecondsMultiplier;
+double g_ClockSpeedSecondsMultiplier;
+
+// Constructor init the clock speed.
+CClockSpeedInit g_ClockSpeedInit CONSTRUCT_EARLY;
+
+void CClockSpeedInit::Init()
+{
+	const CPUInformation& cpuinfo = *GetCPUInformation();
+
+	g_ClockSpeed = cpuinfo.m_Speed;
+
+	// cycle counter runs as doc'd at 1/64 Xbox 3.2GHz clock speed, thus 50 Mhz
+	if ( IsX360() )
+	{
+		g_ClockSpeed /= 64L;
+	}
+
+	// Avoid integer overflow when writing to g_dwClockSpeed
+	if ( g_ClockSpeed <= ULONG_MAX )
+		g_dwClockSpeed = (unsigned long)g_ClockSpeed;
+	else
+		g_dwClockSpeed = ULONG_MAX;
+
+	g_ClockSpeedMicrosecondsMultiplier = 1000000.0 / (double)g_ClockSpeed;
+	g_ClockSpeedMillisecondsMultiplier = 1000.0 / (double)g_ClockSpeed;
+	g_ClockSpeedSecondsMultiplier = 1.0 / (double)g_ClockSpeed;
+}