Implemented a new sequence number unwrapper in sequence_number_util.h.

webrtc/rtc_base/mod_ops_unittest.cc

Index: webrtc/rtc_base/mod_ops_unittest.cc
diff --git a/webrtc/rtc_base/mod_ops_unittest.cc b/webrtc/rtc_base/mod_ops_unittest.cc
index c375305e2d3c15e1821f342c5a701db0dc5b6c23..dc82c23cdffa9110d08710b8cba84264aad234d7 100644
--- a/webrtc/rtc_base/mod_ops_unittest.cc
+++ b/webrtc/rtc_base/mod_ops_unittest.cc
@@ -87,6 +87,17 @@ TEST_F(TestModOps, ForwardDiff) {
   }
 }
 
+TEST_F(TestModOps, ForwardDiffWithDivisor) {
+  const uint8_t kDiv = 123;
+  uint8_t x = 0;
+  uint8_t y = kDiv - 1;
+  for (int i = 0; i < kDiv; ++i) {
+    ASSERT_EQ(kDiv - 1, (ForwardDiff<uint8_t, kDiv>(x, y)));
+    x = (x + 1) % kDiv;
+    y = (y + 1) % kDiv;
+  }
+}
+
 TEST_F(TestModOps, ReverseDiff) {
   ASSERT_EQ(0u, ReverseDiff(4711u, 4711u));
 
@@ -106,6 +117,17 @@ TEST_F(TestModOps, ReverseDiff) {
   }
 }
 
+TEST_F(TestModOps, ReverseDiffWithDivisor) {
+  const uint8_t kDiv = 13;
+  uint8_t x = 0;
+  uint8_t y = kDiv - 1;
+  for (int i = 0; i < kDiv; ++i) {
+    ASSERT_EQ(1, (ReverseDiff<uint8_t, kDiv>(x, y)));
+    x = (x + 1) % kDiv;
+    y = (y + 1) % kDiv;
+  }
+}
+
 TEST_F(TestModOps, MinDiff) {
   for (uint16_t i = 0; i < 256; ++i) {
     ASSERT_EQ(0, MinDiff<uint8_t>(i, i));