133 lines
2.8 KiB
C++
133 lines
2.8 KiB
C++
/*
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* Copyright 2003-2017 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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
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* GNU 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 License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_PIPE_H
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#define MPD_PIPE_H
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#include "thread/Mutex.hxx"
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#include "Compiler.h"
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#ifndef NDEBUG
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#include "AudioFormat.hxx"
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#endif
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#include <assert.h>
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struct MusicChunk;
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class MusicBuffer;
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/**
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* A queue of #MusicChunk objects. One party appends chunks at the
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* tail, and the other consumes them from the head.
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*/
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class MusicPipe {
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/** the first chunk */
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MusicChunk *head = nullptr;
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/** a pointer to the tail of the chunk */
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MusicChunk **tail_r = &head;
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/** the current number of chunks */
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unsigned size = 0;
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/** a mutex which protects #head and #tail_r */
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mutable Mutex mutex;
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#ifndef NDEBUG
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AudioFormat audio_format = AudioFormat::Undefined();
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#endif
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public:
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/**
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* Creates a new #MusicPipe object. It is empty.
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*/
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MusicPipe() = default;
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MusicPipe(const MusicPipe &) = delete;
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/**
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* Frees the object. It must be empty now.
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*/
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~MusicPipe() {
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assert(head == nullptr);
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assert(tail_r == &head);
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}
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MusicPipe &operator=(const MusicPipe &) = delete;
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#ifndef NDEBUG
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/**
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* Checks if the audio format if the chunk is equal to the specified
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* audio_format.
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*/
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gcc_pure
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bool CheckFormat(AudioFormat other) const {
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return !audio_format.IsDefined() ||
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audio_format == other;
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}
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/**
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* Checks if the specified chunk is enqueued in the music pipe.
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*/
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gcc_pure
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bool Contains(const MusicChunk *chunk) const;
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#endif
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/**
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* Returns the first #MusicChunk from the pipe. Returns
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* nullptr if the pipe is empty.
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*/
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gcc_pure
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const MusicChunk *Peek() const {
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return head;
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}
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/**
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* Removes the first chunk from the head, and returns it.
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*/
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MusicChunk *Shift();
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/**
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* Clears the whole pipe and returns the chunks to the buffer.
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*
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* @param buffer the buffer object to return the chunks to
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*/
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void Clear(MusicBuffer &buffer);
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/**
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* Pushes a chunk to the tail of the pipe.
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*/
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void Push(MusicChunk *chunk);
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/**
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* Returns the number of chunks currently in this pipe.
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*/
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gcc_pure
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unsigned GetSize() const {
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return size;
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}
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gcc_pure
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bool IsEmpty() const {
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return GetSize() == 0;
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}
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};
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#endif
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