win: clock implementation

util/misc/clock_win.cc

Index: util/misc/clock_win.cc
diff --git a/util/misc/clock_win.cc b/util/misc/clock_win.cc
new file mode 100644
index 0000000000000000000000000000000000000000..731e98d4ee29da76306d598f4ee02ec64cffa99d
--- /dev/null
+++ b/util/misc/clock_win.cc
@@ -0,0 +1,48 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/misc/clock.h"
+
+#include <sys/types.h>
+#include <windows.h>
+
+namespace {
+
+LARGE_INTEGER QpcFrequencyInternal() {
+  LARGE_INTEGER frequency;
+  QueryPerformanceFrequency(&frequency);
+  return frequency;
+}
+
+int64_t QpcFrequency() {
+  static LARGE_INTEGER frequency = QpcFrequencyInternal();
+  return frequency.QuadPart;
+}
+
+}  // namespace
+
+namespace crashpad {
+
+uint64_t ClockMonotonicNanoseconds() {
+  LARGE_INTEGER time;
+  QueryPerformanceCounter(&time);
+  int64_t frequency = QpcFrequency();
+  int64_t whole_seconds = time.QuadPart / frequency;
+  int64_t leftover_ticks = time.QuadPart / (whole_seconds * frequency);
+  const int64_t kNanosecondsPerSecond = static_cast<const int64_t>(1E9);
+  return (whole_seconds * kNanosecondsPerSecond) +
+         ((leftover_ticks * kNanosecondsPerSecond) / frequency);
+}
+
+}  // namespace crashpad