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diff --git a/lib/os/os_time.hpp b/lib/os/os_time.hpp
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+/**************************************************************************
+ *
+ * Copyright 2011 Jose Fonseca
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ **************************************************************************/
+
+/*
+ * Simple OS time measurement abstraction.
+ */
+
+#pragma once
+
+
+#if defined(_WIN32)
+#  include <windows.h>
+#else
+#  if defined(__linux__)
+#    include <time.h>
+#  elif defined(__APPLE__)
+#    include <mach/mach_time.h>
+#  else
+#    include <sys/time.h>
+#  endif
+#  include <unistd.h>
+#endif
+
+
+namespace os {
+
+    // OS dependent time frequency
+#if defined(_WIN32) || defined(__APPLE__)
+    // runtime variable on Windows and MacOSX
+    extern long long timeFrequency;
+#elif defined(__linux__)
+    // nanoseconds on Linux
+    static const long long timeFrequency = 1000000000LL;
+#else
+    // microseconds on Unices
+    static const long long timeFrequency = 1000000LL;
+#endif
+
+    // Time from an unknown base in a unit determined by timeFrequency
+    inline long long
+    getTime(void) {
+#if defined(_WIN32)
+        if (!timeFrequency) {
+            LARGE_INTEGER frequency;
+            QueryPerformanceFrequency(&frequency);
+            timeFrequency = frequency.QuadPart;
+        }
+        LARGE_INTEGER counter;
+        QueryPerformanceCounter(&counter);
+        return counter.QuadPart;
+#elif defined(__linux__)
+        struct timespec tp;
+        if (clock_gettime(CLOCK_MONOTONIC, &tp) == -1) {
+            return 0;
+        }
+        return tp.tv_sec * 1000000000LL + tp.tv_nsec;
+#elif defined(__APPLE__)
+        if (!timeFrequency) {
+            mach_timebase_info_data_t timebaseInfo;
+            mach_timebase_info(&timebaseInfo);
+            timeFrequency = 1000000000LL * timebaseInfo.denom / timebaseInfo.numer;
+        }
+        return mach_absolute_time();
+#else
+        struct timeval tv;
+        gettimeofday(&tv, NULL);
+        return tv.tv_sec * 1000000LL + tv.tv_usec;
+#endif
+    }
+
+    // Suspend execution
+    inline void
+    sleep(unsigned long usecs) {
+#if defined(_WIN32)
+        Sleep((usecs + 999) / 1000);
+#else
+        usleep(usecs);
+#endif
+    }
+
+} /* namespace os */
+