Add nanosecond timer.

src/ports/SkTime_Unix.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkTime.h"
 
 #include <sys/time.h>
 #include <time.h>
 
-void SkTime::GetDateTime(DateTime* dt)
-{
-    if (dt)
-    {
+void SkTime::GetDateTime(DateTime* dt) {
+    if (dt) {
         time_t m_time;
         time(&m_time);
         struct tm* tstruct;
         tstruct = localtime(&m_time);
 
         dt->fYear       = tstruct->tm_year;
         dt->fMonth      = SkToU8(tstruct->tm_mon + 1);
         dt->fDayOfWeek  = SkToU8(tstruct->tm_wday);
         dt->fDay        = SkToU8(tstruct->tm_mday);
         dt->fHour       = SkToU8(tstruct->tm_hour);
         dt->fMinute     = SkToU8(tstruct->tm_min);
         dt->fSecond     = SkToU8(tstruct->tm_sec);
     }
 }
 
-SkMSec SkTime::GetMSecs()
-{
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    return (SkMSec) (tv.tv_sec * 1000 + tv.tv_usec / 1000 ); // microseconds to milliseconds
+#ifdef __MACH__
+#  include <mach/mach_time.h>
+
+namespace {
+
+struct ConversionFactor {
+    ConversionFactor() {
+        mach_timebase_info_data_t timebase;
+        mach_timebase_info(&timebase);
+        toNanos = (double) timebase.numer / timebase.denom;
+    }
+    double toNanos;
+};
+
+}  // namespace
+
+SkNSec SkTime::GetNSecs() {
+    static ConversionFactor convert;  // Since already know we're on Mac, this is threadsafe.
+    return mach_absolute_time() * convert.toNanos;
 }
+
+#else  // Linux, presumably all others too
+
+SkNSec SkTime::GetNSecs() {
+    struct timespec time;
+    clock_gettime(CLOCK_MONOTONIC, &time);
+    return (SkNSec)(time.tv_sec * 1000000000 + time.tv_nsec);
+}
+
+#endif