Fuchsia port of base/time, with some refactoring of POSIX time modules.

base/time/time_fuchsia.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/time/time.h"
+
+#include <magenta/syscalls.h>
+
+#include "base/compiler_specific.h"
+
+namespace base {
+
+namespace {
+
+// Helper function to map an unsigned integer with nanosecond timebase to a
+// signed integer with microsecond timebase.
+ALWAYS_INLINE int64_t MxTimeToMicroseconds(mx_time_t nanos) {
+  const mx_time_t micros =
+      nanos / static_cast<mx_time_t>(base::Time::kNanosecondsPerMicrosecond);
+  return static_cast<int64_t>(micros);
+}
+
+}  // namespace
+
+// Time -----------------------------------------------------------------------
+
+// static
+Time Time::Now() {
+  const mx_time_t nanos_since_unix_epoch = mx_time_get(MX_CLOCK_UTC);
+  CHECK(nanos_since_unix_epoch != 0);
+  // The following expression will overflow in the year 289938 A.D.:
+  return Time(MxTimeToMicroseconds(nanos_since_unix_epoch) +
+              kTimeTToMicrosecondsOffset);
+}
+
+// static
+Time Time::NowFromSystemTime() {
+  return Now();
+}
+
+// TimeTicks ------------------------------------------------------------------
+
+// static
+TimeTicks TimeTicks::Now() {
+  const mx_time_t nanos_since_boot = mx_time_get(MX_CLOCK_MONOTONIC);
+  CHECK(nanos_since_boot != 0);
+  return TimeTicks(MxTimeToMicroseconds(nanos_since_boot));
+}
+
+// static
+TimeTicks::Clock TimeTicks::GetClock() {
+  return Clock::FUCHSIA_MX_CLOCK_MONOTONIC;
+}
+
+// static
+bool TimeTicks::IsHighResolution() {
+  return true;
+}
+
+// static
+bool TimeTicks::IsConsistentAcrossProcesses() {
+  return true;
+}
+
+// static
+TimeTicks TimeTicks::FromMXTime(mx_time_t nanos_since_boot) {
+  return TimeTicks(MxTimeToMicroseconds(nanos_since_boot));
+}
+
+// static
+ThreadTicks ThreadTicks::Now() {
+  const mx_time_t nanos_since_thread_started = mx_time_get(MX_CLOCK_THREAD);
+  CHECK(nanos_since_thread_started != 0);
+  return ThreadTicks(MxTimeToMicroseconds(nanos_since_thread_started));
+}
+
+}  // namespace base