[rtp_rtcp] time helper functions

webrtc/modules/rtp_rtcp/source/time_util_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/time_util_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/time_util_unittest.cc b/webrtc/modules/rtp_rtcp/source/time_util_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7efb83ccadc50e24cea84b40a87e450b51e3ac37
--- /dev/null
+++ b/webrtc/modules/rtp_rtcp/source/time_util_unittest.cc
@@ -0,0 +1,62 @@
+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "webrtc/modules/rtp_rtcp/source/time_util.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace webrtc {
+
+TEST(TimeUtilTest, CompactNtp) {
+  const uint32_t kNtpSec = 0x12345678;
+  const uint32_t kNtpFrac = 0x23456789;
+  const NtpTime kNtp(kNtpSec, kNtpFrac);
+  const uint32_t kNtpMid = 0x56782345;
+  EXPECT_EQ(kNtpMid, CompactNtp(kNtp));
+}
+
+TEST(TimeUtilTest, CompactNtpToMs) {
+  const NtpTime ntp1(0x12345, 0x23456);
+  const NtpTime ntp2(0x12654, 0x64335);
+  uint32_t ms_diff = ntp2.ToMs() - ntp1.ToMs();
+  uint32_t ntp_diff = CompactNtp(ntp2) - CompactNtp(ntp1);
+
+  uint32_t ntp_to_ms_diff = CompactNtpIntervalToMs(ntp_diff);
+
+  EXPECT_NEAR(ms_diff, ntp_to_ms_diff, 1);
+}
+
+TEST(TimeUtilTest, CompactNtpToMsWithWrap) {
+  const NtpTime ntp1(0x1ffff, 0x23456);
+  const NtpTime ntp2(0x20000, 0x64335);
+  uint32_t ms_diff = ntp2.ToMs() - ntp1.ToMs();
+
+  // While ntp2 > ntp1, there compact ntp presentation happen to be opposite.
+  // That shouldn't be a problem as long as unsigned arithmetic is used.
+  ASSERT_GT(ntp2.ToMs(), ntp1.ToMs());
+  ASSERT_LT(CompactNtp(ntp2), CompactNtp(ntp1));
+
+  uint32_t ntp_diff = CompactNtp(ntp2) - CompactNtp(ntp1);
+  uint32_t ntp_to_ms_diff = CompactNtpIntervalToMs(ntp_diff);
+
+  EXPECT_NEAR(ms_diff, ntp_to_ms_diff, 1);
+}
+
+TEST(TimeUtilTest, CompactNtpToMsLarge) {
+  const NtpTime ntp1(0x10000, 0x23456);
+  const NtpTime ntp2(0x1ffff, 0x64335);
+  uint32_t ms_diff = ntp2.ToMs() - ntp1.ToMs();
+  // Ntp difference close to maximum of ~18 hours should convert correctly too.
+  ASSERT_GT(ms_diff, 18u * 3600 * 1000);
+  uint32_t ntp_diff = CompactNtp(ntp2) - CompactNtp(ntp1);
+  uint32_t ntp_to_ms_diff = CompactNtpIntervalToMs(ntp_diff);
+
+  EXPECT_NEAR(ms_diff, ntp_to_ms_diff, 1);
+}
+}  // namespace webrtc