AGC2 RNN VAD: Ring buffer

Ring buffer template for a finite number of arrays of given type and size.

Bug: webrtc:9076
Change-Id: Ia6c2065b0013f4a00f693966641f9aebe09f6f5c
Reviewed-on: https://webrtc-review.googlesource.com/70161
Reviewed-by: Alex Loiko <aleloi@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22939}

modules/audio_processing/agc2/rnn_vad/BUILD.gn

@@ -17,6 +17,7 @@ group("rnn_vad") {
 source_set("lib") {
   sources = [
     "common.h",
+    "ring_buffer.h",
     "sequence_buffer.h",
   ]
   deps = [
@@ -29,6 +30,7 @@ if (rtc_include_tests) {
   rtc_source_set("unittests") {
     testonly = true
     sources = [
+      "ring_buffer_unittest.cc",
       "sequence_buffer_unittest.cc",
     ]
     deps = [

modules/audio_processing/agc2/rnn_vad/ring_buffer.h

@@ -0,0 +1,66 @@
+/*
+ *  Copyright (c) 2018 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.
+ */
+
+#ifndef MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_RING_BUFFER_H_
+#define MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_RING_BUFFER_H_
+
+#include <array>
+#include <cstring>
+#include <type_traits>
+
+#include "api/array_view.h"
+
+namespace webrtc {
+namespace rnn_vad {
+
+// Ring buffer for N arrays of type T each one with size S.
+template <typename T, size_t S, size_t N>
+class RingBuffer {
+  static_assert(S > 0, "");
+  static_assert(N > 0, "");
+  static_assert(std::is_arithmetic<T>::value,
+                "Integral or floating point required.");
+
+ public:
+  RingBuffer() : tail_(0) {}
+  RingBuffer(const RingBuffer&) = delete;
+  RingBuffer& operator=(const RingBuffer&) = delete;
+  ~RingBuffer() = default;
+  // Set the ring buffer values to zero.
+  void Reset() { buffer_.fill(0); }
+  // Replace the least recently pushed array in the buffer with |new_values|.
+  void Push(rtc::ArrayView<const T, S> new_values) {
+    std::memcpy(buffer_.data() + S * tail_, new_values.data(), S * sizeof(T));
+    tail_ += 1;
+    if (tail_ == N)
+      tail_ = 0;
+  }
+  // Return an array view onto the array with a given delay. A view on the last
+  // and least recently push array is returned when |delay| is 0 and N - 1
+  // respectively.
+  rtc::ArrayView<const T, S> GetArrayView(size_t delay) const {
+    const int delay_int = static_cast<int>(delay);
+    RTC_DCHECK_LE(0, delay_int);
+    RTC_DCHECK_LT(delay_int, N);
+    int offset = tail_ - 1 - delay_int;
+    if (offset < 0)
+      offset += N;
+    return {buffer_.data() + S * offset, S};
+  }
+
+ private:
+  int tail_;  // Index of the least recently pushed sub-array.
+  std::array<T, S * N> buffer_{};
+};
+
+}  // namespace rnn_vad
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_RING_BUFFER_H_

modules/audio_processing/agc2/rnn_vad/ring_buffer_unittest.cc

@@ -0,0 +1,116 @@
+/*
+ *  Copyright (c) 2018 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 "modules/audio_processing/agc2/rnn_vad/ring_buffer.h"
+
+#include "test/gtest.h"
+
+namespace webrtc {
+namespace test {
+
+using rnn_vad::RingBuffer;
+
+namespace {
+
+// Compare the elements of two given array views.
+template <typename T, std::ptrdiff_t S>
+void ExpectEq(rtc::ArrayView<const T, S> a, rtc::ArrayView<const T, S> b) {
+  for (size_t i = 0; i < S; ++i) {
+    SCOPED_TRACE(i);
+    EXPECT_EQ(a[i], b[i]);
+  }
+}
+
+// Test push/read sequences.
+template <typename T, size_t S, size_t N>
+void TestRingBuffer() {
+  SCOPED_TRACE(N);
+  SCOPED_TRACE(S);
+  std::array<T, S> prev_pushed_array;
+  std::array<T, S> pushed_array;
+  rtc::ArrayView<const T, S> pushed_array_view(pushed_array.data(), S);
+
+  // Init.
+  RingBuffer<T, S, N> ring_buf;
+  ring_buf.GetArrayView(0);
+  pushed_array.fill(0);
+  ring_buf.Push(pushed_array_view);
+  ExpectEq(pushed_array_view, ring_buf.GetArrayView(0));
+
+  // Push N times and check most recent and second most recent.
+  for (T v = 1; v <= static_cast<T>(N); ++v) {
+    SCOPED_TRACE(v);
+    prev_pushed_array = pushed_array;
+    pushed_array.fill(v);
+    ring_buf.Push(pushed_array_view);
+    ExpectEq(pushed_array_view, ring_buf.GetArrayView(0));
+    if (N > 1) {
+      pushed_array.fill(v - 1);
+      ExpectEq(pushed_array_view, ring_buf.GetArrayView(1));
+    }
+  }
+
+  // Check buffer.
+  for (size_t delay = 2; delay < N; ++delay) {
+    SCOPED_TRACE(delay);
+    T expected_value = N - static_cast<T>(delay);
+    pushed_array.fill(expected_value);
+    ExpectEq(pushed_array_view, ring_buf.GetArrayView(delay));
+  }
+}
+
+}  // namespace
+
+// Check that for different delays, different views are returned.
+TEST(RnnVadTest, RingBufferArrayViews) {
+  constexpr size_t s = 3;
+  constexpr size_t n = 4;
+  RingBuffer<int, s, n> ring_buf;
+  std::array<int, s> pushed_array;
+  pushed_array.fill(1);
+  for (size_t k = 0; k <= n; ++k) {  // Push data n + 1 times.
+    SCOPED_TRACE(k);
+    // Check array views.
+    for (size_t i = 0; i < n; ++i) {
+      SCOPED_TRACE(i);
+      auto view_i = ring_buf.GetArrayView(i);
+      for (size_t j = i + 1; j < n; ++j) {
+        SCOPED_TRACE(j);
+        auto view_j = ring_buf.GetArrayView(j);
+        EXPECT_NE(view_i, view_j);
+      }
+    }
+    ring_buf.Push({pushed_array.data(), pushed_array.size()});
+  }
+}
+
+TEST(RnnVadTest, RingBufferUnsigned) {
+  TestRingBuffer<uint8_t, 1, 1>();
+  TestRingBuffer<uint8_t, 2, 5>();
+  TestRingBuffer<uint8_t, 5, 2>();
+  TestRingBuffer<uint8_t, 5, 5>();
+}
+
+TEST(RnnVadTest, RingBufferSigned) {
+  TestRingBuffer<int, 1, 1>();
+  TestRingBuffer<int, 2, 5>();
+  TestRingBuffer<int, 5, 2>();
+  TestRingBuffer<int, 5, 5>();
+}
+
+TEST(RnnVadTest, RingBufferFloating) {
+  TestRingBuffer<float, 1, 1>();
+  TestRingBuffer<float, 2, 5>();
+  TestRingBuffer<float, 5, 2>();
+  TestRingBuffer<float, 5, 5>();
+}
+
+}  // namespace test
+}  // namespace webrtc