From 5336f1085c327ca06f5f549448c5cc594a4fe7b2 Mon Sep 17 00:00:00 2001
From: "alexey.lysiuk" <alexey.lysiuk@gmail.com>
Date: Sun, 11 Jan 2015 10:30:30 +0200
Subject: [PATCH] Fixed incorrect value that I_FPSTime() may return when OS X
 thread-based timer implementation is used

---
 src/posix/cocoa/i_timer.cpp | 42 +++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/src/posix/cocoa/i_timer.cpp b/src/posix/cocoa/i_timer.cpp
index 319cdd2b83..b08a43139d 100644
--- a/src/posix/cocoa/i_timer.cpp
+++ b/src/posix/cocoa/i_timer.cpp
@@ -32,6 +32,7 @@
  */
 
 #include <assert.h>
+#include <sys/sysctl.h>
 #include <sys/time.h>
 #include <pthread.h>
 #include <libkern/OSAtomic.h>
@@ -43,34 +44,23 @@
 #include "templates.h"
 
 
-static timeval s_startTicks;
-
-
-unsigned int I_MSTime()
+namespace
 {
-	timeval now;
-	gettimeofday(&now, NULL);
 
-	const uint32_t ticks =
-		  (now.tv_sec  - s_startTicks.tv_sec ) * 1000
-		+ (now.tv_usec - s_startTicks.tv_usec) / 1000;
+timeval s_gameStartTicks;
+timeval s_systemBootTicks;
 
-	return ticks;
-}
-
-unsigned int I_FPSTime()
+unsigned int GetMillisecondsSince(const timeval& time)
 {
 	timeval now;
 	gettimeofday(&now, NULL);
 
 	return static_cast<unsigned int>(
-		(now.tv_sec) * 1000 + (now.tv_usec) / 1000);
+		  (now.tv_sec  - time.tv_sec ) * 1000
+		+ (now.tv_usec - time.tv_usec) / 1000);
 }
 
 
-namespace
-{
-
 bool s_isTicFrozen;
 
 timespec GetNextTickTime()
@@ -185,6 +175,17 @@ void FreezeTimeThreaded(bool frozen)
 } // unnamed namespace
 
 
+unsigned int I_MSTime()
+{
+	return GetMillisecondsSince(s_gameStartTicks);
+}
+
+unsigned int I_FPSTime()
+{
+	return GetMillisecondsSince(s_systemBootTicks);
+}
+
+
 fixed_t I_GetTimeFrac(uint32* ms)
 {
 	const uint32_t now = I_MSTime();
@@ -205,7 +206,12 @@ void I_InitTimer()
 	assert(!s_timerInitialized);
 	s_timerInitialized = true;
 
-	gettimeofday(&s_startTicks, NULL);
+	gettimeofday(&s_gameStartTicks, NULL);
+
+	int mib[2] = { CTL_KERN, KERN_BOOTTIME };
+	size_t len = sizeof s_systemBootTicks;
+
+	sysctl(mib, 2, &s_systemBootTicks, &len, NULL, 0);
 
 	pthread_cond_init (&s_timerEvent,  NULL);
 	pthread_mutex_init(&s_timerMutex,  NULL);