From 1cdfcb4935f2cdbc28cefb6ef1c716088643f030 Mon Sep 17 00:00:00 2001
From: "alexey.lysiuk" <alexey.lysiuk@gmail.com>
Date: Tue, 31 Jan 2017 15:56:58 +0200
Subject: [PATCH] RDTSC-based cycle_t for macOS

Windows and macOS now share most of related code
Old implementation using mach_absolute_time() was more precise (at least in theory) but too costly
---
 src/posix/cocoa/i_system.mm | 21 +++++++++++
 src/stats.cpp               |  9 -----
 src/stats.h                 | 75 +------------------------------------
 3 files changed, 22 insertions(+), 83 deletions(-)

diff --git a/src/posix/cocoa/i_system.mm b/src/posix/cocoa/i_system.mm
index 2e27a8002..35b71c64b 100644
--- a/src/posix/cocoa/i_system.mm
+++ b/src/posix/cocoa/i_system.mm
@@ -36,6 +36,7 @@
 #include <fnmatch.h>
 #include <unistd.h>
 #include <sys/stat.h>
+#include <sys/sysctl.h>
 
 #include "d_ticcmd.h"
 #include "doomdef.h"
@@ -98,9 +99,29 @@ void SetLanguageIDs()
 void I_InitTimer();
 void I_ShutdownTimer();
 
+double PerfToSec, PerfToMillisec;
+
+static void CalculateCPUSpeed()
+{
+	long long frequency;
+	size_t size = sizeof frequency;
+
+	if (0 == sysctlbyname("machdep.tsc.frequency", &frequency, &size, nullptr, 0) && 0 != frequency)
+	{
+		PerfToSec = 1.0 / frequency;
+		PerfToMillisec = 1000.0 / frequency;
+
+		if (!batchrun)
+		{
+			Printf("CPU speed: %.0f MHz\n", 0.001 / PerfToMillisec);
+		}
+	}
+}
+
 void I_Init(void)
 {
 	CheckCPUID(&CPU);
+	CalculateCPUSpeed();
 	DumpCPUInfo(&CPU);
 
 	atterm(I_ShutdownSound);
diff --git a/src/stats.cpp b/src/stats.cpp
index c57b32640..237436c41 100644
--- a/src/stats.cpp
+++ b/src/stats.cpp
@@ -42,15 +42,6 @@
 #include "m_swap.h"
 #include "sbar.h"
 
-
-#if defined (__APPLE__)
-
-mach_timebase_info_data_t cycle_t::s_info;
-bool cycle_t::s_initialized;
-
-#endif // __APPLE__
-
-
 FStat *FStat::FirstStat;
 
 FStat::FStat (const char *name)
diff --git a/src/stats.h b/src/stats.h
index d90efa7e4..316633983 100644
--- a/src/stats.h
+++ b/src/stats.h
@@ -36,78 +36,7 @@
 
 #include "zstring.h"
 
-#ifndef _WIN32
-
-#if defined (__APPLE__)
-
-
-#include <mach/mach_time.h>
-
-
-class cycle_t
-{
-public:
-	cycle_t()
-	{
-		if ( !s_initialized )
-		{
-			mach_timebase_info( &s_info );
-			s_initialized = true;
-		}
-		
-		Reset();
-	}
-	
-	cycle_t &operator=( const cycle_t &other )
-	{
-		if ( &other != this )
-		{
-			m_seconds = other.m_seconds;
-
-		}
-		
-		return *this;
-	}
-	
-	void Reset()
-	{
-		m_seconds = 0;
-	}
-	
-	void Clock()
-	{
-		m_seconds -= Nanoseconds() * 1e-9;
-	}
-	
-	void Unclock()
-	{
-		m_seconds += Nanoseconds() * 1e-9;
-	}
-	
-	double Time()
-	{
-		return m_seconds;
-	}
-	
-	double TimeMS()
-	{
-		return m_seconds * 1e3;
-	}
-	
-private:
-	double m_seconds;
-	
-	static mach_timebase_info_data_t s_info;
-	static bool s_initialized;
-	
-	uint64_t Nanoseconds() const
-	{
-		return mach_absolute_time() * s_info.numer / s_info.denom;
-	}
-	
-};
-
-#else // !__APPLE__
+#if !defined _WIN32 && !defined __APPLE__
 
 #ifdef NO_CLOCK_GETTIME
 class cycle_t
@@ -171,8 +100,6 @@ private:
 
 #endif
 
-#endif // __APPLE__
-
 #else
 
 // Windows