Source codes

1 files changed, 65 insertions, 0 deletions

diff --git a/Whisper/Utils/CpuProfiler.cpp b/Whisper/Utils/CpuProfiler.cpp
new file mode 100644
index 0000000..6161e95
--- /dev/null
+++ b/Whisper/Utils/CpuProfiler.cpp
@@ -0,0 +1,65 @@
+#include "stdafx.h"
+#include "CpuProfiler.h"
+
+namespace
+{
+	using namespace Whisper;
+
+	inline int64_t qpcNow()
+	{
+		int64_t res;
+		QueryPerformanceCounter( (LARGE_INTEGER*)&res );
+		return res;
+	}
+
+	class CpuTimescale
+	{
+		uint64_t frequency = 0;
+		const int64_t tscStart;
+		const int64_t qpcStart;
+
+		uint64_t computeTscFrequency();
+
+	public:
+
+		CpuTimescale() :
+			tscStart( tscNow() ),
+			qpcStart( qpcNow() )
+		{ }
+
+		inline uint64_t computeTicks( uint64_t tsc )
+		{
+			uint64_t freq = frequency;
+			if( freq == 0 )
+				freq = computeTscFrequency();
+
+			return makeTime( tsc, freq );
+		}
+	};
+
+	uint64_t __declspec( noinline ) CpuTimescale::computeTscFrequency()
+	{
+		int64_t tsc = tscNow();
+		int64_t qpc = qpcNow();
+		tsc -= tscStart;
+		qpc -= qpcStart;
+
+		uint64_t qpcFreq;
+		QueryPerformanceFrequency( (LARGE_INTEGER*)&qpcFreq );
+
+		// Seconds = qpc / qpcFreq
+		// ticks per second = tsc / seconds = tsc * qpcFreq / qpc
+		uint64_t res = ( (uint64_t)tsc * qpcFreq + ( (uint64_t)qpc / 2 ) - 1 ) / (uint64_t)qpc;
+		frequency = res;
+		const double GHz = (double)(int64_t)res * 1.0E-9;
+		logDebug( u8"Computed CPU base frequency: %g GHz", GHz );
+		return res;
+	}
+
+	static CpuTimescale timescale;
+}
+
+uint64_t Whisper::ticksFromTsc( uint64_t tscDiff )
+{
+	return timescale.computeTicks( tscDiff );
+}
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