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* 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 <algorithm>
#include <cstring>
#include <type_traits>
#include <vector>
#include "api/array_view.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace rnn_vad {
// Linear buffer implementation to (i) push fixed size chunks of sequential data
// and (ii) view contiguous parts of the buffer. The buffer and the pushed
// chunks have size S and N respectively. For instance, when S = 2N the first
// half of the sequence buffer is replaced with its second half, and the new N
// values are written at the end of the buffer.
// The class also provides a view on the most recent M values, where 0 < M <= S
// and by default M = N.
template <typename T, int S, int N, int M = N>
class SequenceBuffer {
static_assert(N <= S,
"The new chunk size cannot be larger than the sequence buffer "
"Integral or floating point required.");
SequenceBuffer() : buffer_(S) {
RTC_DCHECK_EQ(S, buffer_.size());
SequenceBuffer(const SequenceBuffer&) = delete;
SequenceBuffer& operator=(const SequenceBuffer&) = delete;
~SequenceBuffer() = default;
int size() const { return S; }
int chunks_size() const { return N; }
// Sets the sequence buffer values to zero.
void Reset() { std::fill(buffer_.begin(), buffer_.end(), 0); }
// Returns a view on the whole buffer.
rtc::ArrayView<const T, S> GetBufferView() const {
return {, S};
// Returns a view on the M most recent values of the buffer.
rtc::ArrayView<const T, M> GetMostRecentValuesView() const {
static_assert(M <= S,
"The number of most recent values cannot be larger than the "
"sequence buffer size.");
return { + S - M, M};
// Shifts left the buffer by N items and add new N items at the end.
void Push(rtc::ArrayView<const T, N> new_values) {
// Make space for the new values.
if (S > N)
std::memmove(, + N, (S - N) * sizeof(T));
// Copy the new values at the end of the buffer.
std::memcpy( + S - N,, N * sizeof(T));
std::vector<T> buffer_;
} // namespace rnn_vad
} // namespace webrtc