blob: f0282aaed5e51d11bb76f5365637b4befe98caa5 [file] [log] [blame]
* 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 <array>
#include <cstring>
#include <utility>
#include "api/array_view.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace rnn_vad {
// Data structure to buffer the results of pair-wise comparisons between items
// stored in a ring buffer. Every time that the oldest item is replaced in the
// ring buffer, the new one is compared to the remaining items in the ring
// buffer. The results of such comparisons need to be buffered and automatically
// removed when one of the two corresponding items that have been compared is
// removed from the ring buffer. It is assumed that the comparison is symmetric
// and that comparing an item with itself is not needed.
template <typename T, size_t S>
class SymmetricMatrixBuffer {
static_assert(S > 2, "");
SymmetricMatrixBuffer() = default;
SymmetricMatrixBuffer(const SymmetricMatrixBuffer&) = delete;
SymmetricMatrixBuffer& operator=(const SymmetricMatrixBuffer&) = delete;
~SymmetricMatrixBuffer() = default;
// Sets the buffer values to zero.
void Reset() {
"Integral or floating point required.");
// Pushes the results from the comparison between the most recent item and
// those that are still in the ring buffer. The first element in |values| must
// correspond to the comparison between the most recent item and the second
// most recent one in the ring buffer, whereas the last element in |values|
// must correspond to the comparison between the most recent item and the
// oldest one in the ring buffer.
void Push(rtc::ArrayView<T, S - 1> values) {
// Move the lower-right sub-matrix of size (S-2) x (S-2) one row up and one
// column left.
std::memmove(, + S, (buf_.size() - S) * sizeof(T));
// Copy new values in the last column in the right order.
for (size_t i = 0; i < values.size(); ++i) {
const size_t index = (S - 1 - i) * (S - 1) - 1;
RTC_DCHECK_LE(static_cast<size_t>(0), index);
RTC_DCHECK_LT(index, buf_.size());
buf_[index] = values[i];
// Reads the value that corresponds to comparison of two items in the ring
// buffer having delay |delay1| and |delay2|. The two arguments must not be
// equal and both must be in {0, ..., S - 1}.
T GetValue(size_t delay1, size_t delay2) const {
int row = S - 1 - static_cast<int>(delay1);
int col = S - 1 - static_cast<int>(delay2);
RTC_DCHECK_NE(row, col) << "The diagonal cannot be accessed.";
if (row > col)
std::swap(row, col); // Swap to access the upper-right triangular part.
RTC_DCHECK_LE(0, row);
RTC_DCHECK_LT(row, S - 1) << "Not enforcing row < col and row != col.";
RTC_DCHECK_LE(1, col) << "Not enforcing row < col and row != col.";
const int index = row * (S - 1) + (col - 1);
RTC_DCHECK_LE(0, index);
RTC_DCHECK_LT(index, buf_.size());
return buf_[index];
// Encode an upper-right triangular matrix (excluding its diagonal) using a
// square matrix. This allows to move the data in Push() with one single
// operation.
std::array<T, (S - 1) * (S - 1)> buf_{};
} // namespace rnn_vad
} // namespace webrtc