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https://github.com/LMMS/lmms.git
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134 lines
3.9 KiB
C++
134 lines
3.9 KiB
C++
/*
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* LocklessRingBuffer.h - LMMS wrapper for a lockless ringbuffer library
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*
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* Copyright (c) 2019 Martin Pavelek <he29/dot/HS/at/gmail/dot/com>
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*
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* This file is part of LMMS - https://lmms.io
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program (see COPYING); if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA.
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*
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*/
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#ifndef LOCKLESSRINGBUFFER_H
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#define LOCKLESSRINGBUFFER_H
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#include <QMutex>
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#include <QWaitCondition>
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#include "lmms_basics.h"
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#include "lmms_export.h"
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#include "../src/3rdparty/ringbuffer/include/ringbuffer/ringbuffer.h"
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//! A convenience layer for a realtime-safe and thread-safe multi-reader ring buffer library.
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template <class T>
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class LocklessRingBufferBase
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{
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template<class _T>
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friend class LocklessRingBufferReader;
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public:
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LocklessRingBufferBase(std::size_t sz) : m_buffer(sz)
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{
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m_buffer.touch(); // reserve storage space before realtime operation starts
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}
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~LocklessRingBufferBase() {};
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std::size_t capacity() const {return m_buffer.maximum_eventual_write_space();}
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std::size_t free() const {return m_buffer.write_space();}
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void wakeAll() {m_notifier.wakeAll();}
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protected:
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ringbuffer_t<T> m_buffer;
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QWaitCondition m_notifier;
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};
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// The SampleFrameCopier is required because sampleFrame is just a two-element
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// array and therefore does not have a copy constructor needed by std::copy.
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class SampleFrameCopier
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{
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const sampleFrame* m_src;
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public:
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SampleFrameCopier(const sampleFrame* src) : m_src(src) {}
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void operator()(std::size_t src_offset, std::size_t count, sampleFrame* dest)
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{
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for (std::size_t i = src_offset; i < src_offset + count; i++, dest++)
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{
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(*dest)[0] = m_src[i][0];
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(*dest)[1] = m_src[i][1];
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}
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}
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};
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//! Standard ring buffer template for data types with copy constructor.
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template <class T>
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class LocklessRingBuffer : public LocklessRingBufferBase<T>
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{
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public:
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LocklessRingBuffer(std::size_t sz) : LocklessRingBufferBase<T>(sz) {};
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std::size_t write(const sampleFrame *src, std::size_t cnt, bool notify = false)
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{
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std::size_t written = LocklessRingBufferBase<T>::m_buffer.write(src, cnt);
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// Let all waiting readers know new data are available.
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if (notify) {LocklessRingBufferBase<T>::m_notifier.wakeAll();}
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return written;
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}
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};
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//! Specialized ring buffer template with write function modified to support sampleFrame.
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template <>
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class LocklessRingBuffer<sampleFrame> : public LocklessRingBufferBase<sampleFrame>
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{
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public:
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LocklessRingBuffer(std::size_t sz) : LocklessRingBufferBase<sampleFrame>(sz) {};
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std::size_t write(const sampleFrame *src, std::size_t cnt, bool notify = false)
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{
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SampleFrameCopier copier(src);
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std::size_t written = LocklessRingBufferBase<sampleFrame>::m_buffer.write_func<SampleFrameCopier>(copier, cnt);
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// Let all waiting readers know new data are available.
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if (notify) {LocklessRingBufferBase<sampleFrame>::m_notifier.wakeAll();}
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return written;
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}
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};
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//! Wrapper for lockless ringbuffer reader
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template <class T>
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class LocklessRingBufferReader : public ringbuffer_reader_t<T>
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{
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public:
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LocklessRingBufferReader(LocklessRingBuffer<T> &rb) :
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ringbuffer_reader_t<T>(rb.m_buffer),
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m_notifier(&rb.m_notifier) {};
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bool empty() const {return !this->read_space();}
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void waitForData()
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{
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QMutex useless_lock;
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useless_lock.lock();
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m_notifier->wait(&useless_lock);
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useless_lock.unlock();
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}
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private:
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QWaitCondition *m_notifier;
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};
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#endif //LOCKLESSRINGBUFFER_H
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