119 lines
3.1 KiB
C++
119 lines
3.1 KiB
C++
/*
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* Copyright 2003-2019 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_DECODER_BUFFER_HXX
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#define MPD_DECODER_BUFFER_HXX
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#include "util/Compiler.h"
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#include "util/DynamicFifoBuffer.hxx"
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#include "util/ConstBuffer.hxx"
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#include <stddef.h>
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#include <stdint.h>
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class DecoderClient;
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class InputStream;
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/**
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* This objects handles buffered reads in decoder plugins easily. You
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* create a buffer object, and use its high-level methods to fill and
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* read it. It will automatically handle shifting the buffer.
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*/
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class DecoderBuffer {
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DecoderClient *const client;
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InputStream &is;
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DynamicFifoBuffer<uint8_t> buffer;
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public:
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/**
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* Creates a new buffer.
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*
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* @param _client the decoder client, used for decoder_read(),
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* may be nullptr
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* @param _is the input stream object where we should read from
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* @param _size the maximum size of the buffer
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*/
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DecoderBuffer(DecoderClient *_client, InputStream &_is,
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size_t _size)
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:client(_client), is(_is), buffer(_size) {}
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const InputStream &GetStream() const noexcept {
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return is;
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}
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void Clear() noexcept {
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buffer.Clear();
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}
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/**
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* Read data from the #InputStream and append it to the buffer.
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*
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* @return true if data was appended; false if there is no
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* data available (yet), end of file, I/O error or a decoder
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* command was received
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*/
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bool Fill();
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/**
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* How many bytes are stored in the buffer?
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*/
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gcc_pure
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size_t GetAvailable() const noexcept {
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return buffer.GetAvailable();
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}
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/**
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* Reads data from the buffer. This data is not yet consumed,
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* you have to call Consume() to do that. The returned buffer
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* becomes invalid after a Fill() or a Consume() call.
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*/
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ConstBuffer<void> Read() const noexcept {
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auto r = buffer.Read();
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return { r.data, r.size };
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}
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/**
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* Wait until this number of bytes are available. Returns nullptr on
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* error.
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*/
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ConstBuffer<void> Need(size_t min_size);
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/**
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* Consume (delete, invalidate) a part of the buffer. The
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* "nbytes" parameter must not be larger than the length
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* returned by Read().
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*
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* @param nbytes the number of bytes to consume
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*/
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void Consume(size_t nbytes) noexcept {
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buffer.Consume(nbytes);
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}
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/**
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* Skips the specified number of bytes, discarding its data.
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*
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* @param nbytes the number of bytes to skip
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* @return true on success, false on error
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*/
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bool Skip(size_t nbytes);
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};
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#endif
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