Adding BlockMeanCalculator for AEC.

webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc

Index: webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc
diff --git a/webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc b/webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f8e7387dce8a45406ee71fdbc5980e811fd75b8a
--- /dev/null
+++ b/webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc
@@ -0,0 +1,55 @@
+/*
+ *  Copyright (c) 2016 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 "testing/gtest/include/gtest/gtest.h"
+
+#include "webrtc/modules/audio_processing/utility/mean_calculator.h"
+
+namespace webrtc {
+
+TEST(MeanCalculatorTest, Correctness) {
+  const size_t kBlockLength = 10;
+  BlockMeanCalculator mean_calculator(kBlockLength);
+  size_t i = 0;
+  float reference = 0.0;
+
+  for (; i < kBlockLength; ++i) {
+    EXPECT_EQ(mean_calculator.SamplesSinceLastUpdate(), i % kBlockLength);
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  for (; i < 3 * kBlockLength; ++i) {
+    const size_t new_samples = i % kBlockLength;
+    if (new_samples == 0) {
+      // Sum of (i - kBlockLength) ... (i - 1)
+      reference = i - 0.5 * (1 + kBlockLength);
+    }
+    EXPECT_EQ(mean_calculator.SamplesSinceLastUpdate(), new_samples);
+    EXPECT_EQ(reference, mean_calculator.GetLatestMean());
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+}
+
+TEST(MeanCalculatorTest, Reset) {
+  const size_t kBlockLength = 10;
+  BlockMeanCalculator mean_calculator(kBlockLength);
+  for (size_t i = 0; i < kBlockLength - 1; ++i) {
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  EXPECT_EQ(mean_calculator.SamplesSinceLastUpdate(), kBlockLength - 1);
+  mean_calculator.Reset();
+  for (size_t i = 0; i < kBlockLength; ++i) {
+    EXPECT_EQ(mean_calculator.SamplesSinceLastUpdate(), i);
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  EXPECT_EQ(mean_calculator.SamplesSinceLastUpdate(), 0u);
+  EXPECT_EQ(mean_calculator.GetLatestMean(), 0.5 * (kBlockLength - 1));
+}
+
+}  // namespace webrtc