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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_AUDIO_RING_BUFFER_H_
+#define MOZILLA_AUDIO_RING_BUFFER_H_
+
+#include "AudioSampleFormat.h"
+#include "mozilla/Span.h"
+
+#include <functional>
+
+namespace mozilla {
+
+/**
+ * AudioRingBuffer works with audio sample format float or short. The
+ * implementation wrap around the RingBuffer thus it is not thread-safe. Reads
+ * and writes must happen in the same thread which may be different than the
+ * construction thread. The memory is pre-allocated in the constructor, but may
+ * also be re-allocated on the fly should a larger length be needed. The sample
+ * format has to be specified in order to be used.
+ */
+class AudioRingBuffer final {
+ public:
+ explicit AudioRingBuffer(uint32_t aSizeInBytes);
+ ~AudioRingBuffer();
+
+ /**
+ * Set the sample format to either short or float. The sample format must be
+ * set before the using any other method.
+ */
+ void SetSampleFormat(AudioSampleFormat aFormat);
+
+ /**
+ * Write `aBuffer.Length()` number of samples when the format is float.
+ */
+ uint32_t Write(const Span<const float>& aBuffer);
+
+ /**
+ * Write `aBuffer.Length()` number of samples when the format is short.
+ */
+ uint32_t Write(const Span<const int16_t>& aBuffer);
+
+ /**
+ * Write `aSamples` number of samples from `aBuffer`. Note the `aBuffer` does
+ * not change.
+ */
+ uint32_t Write(const AudioRingBuffer& aBuffer, uint32_t aSamples);
+
+ /**
+ * Write `aSamples` number of zeros before the beginning of the existing data.
+ */
+ uint32_t PrependSilence(uint32_t aSamples);
+
+ /**
+ * Write `aSamples` number of zeros.
+ */
+ uint32_t WriteSilence(uint32_t aSamples);
+
+ /**
+ * Read `aBuffer.Length()` number of samples when the format is float.
+ */
+ uint32_t Read(const Span<float>& aBuffer);
+
+ /**
+ * Read `aBuffer.Length()` number of samples when the format is short.
+ */
+ uint32_t Read(const Span<int16_t>& aBuffer);
+
+ /**
+ * Read the internal buffer without extra copies when sample format is float.
+ * Check also the RingBuffer::ReadNoCopy() for more details.
+ */
+ uint32_t ReadNoCopy(
+ std::function<uint32_t(const Span<const float>&)>&& aCallable);
+
+ /**
+ * Read the internal buffer without extra copies when sample format is short.
+ * Check also the RingBuffer::ReadNoCopy() for more details.
+ */
+ uint32_t ReadNoCopy(
+ std::function<uint32_t(const Span<const int16_t>&)>&& aCallable);
+
+ /**
+ * Remove `aSamples` number of samples.
+ */
+ uint32_t Discard(uint32_t aSamples);
+
+ /**
+ * Remove all available samples.
+ */
+ uint32_t Clear();
+
+ /**
+ * Set the length of the ring buffer in bytes. Must be divisible by the sample
+ * size. Will not deallocate memory if the underlying buffer is large enough.
+ * Returns false if setting the length requires allocating memory and the
+ * allocation fails.
+ */
+ bool SetLengthBytes(uint32_t aLengthBytes);
+
+ /**
+ * Return the number of samples this buffer can hold.
+ */
+ uint32_t Capacity() const;
+
+ /**
+ * Return true if the buffer is full.
+ */
+ bool IsFull() const;
+
+ /**
+ * Return true if the buffer is empty.
+ */
+ bool IsEmpty() const;
+
+ /**
+ * Return the number of samples available for writing.
+ */
+ uint32_t AvailableWrite() const;
+
+ /**
+ * Return the number of samples available for reading.
+ */
+ uint32_t AvailableRead() const;
+
+ private:
+ class AudioRingBufferPrivate;
+ UniquePtr<AudioRingBufferPrivate> mPtr;
+};
+
+} // namespace mozilla
+
+#endif // MOZILLA_AUDIO_RING_BUFFER_H_