/*
* Copyright (C) 2003-2015 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_DECODER_BUFFER_HXX
#define MPD_DECODER_BUFFER_HXX
#include "Compiler.h"
#include "util/DynamicFifoBuffer.hxx"
#include "util/ConstBuffer.hxx"
#include <stddef.h>
struct Decoder;
class InputStream;
/**
* This objects handles buffered reads in decoder plugins easily. You
* create a buffer object, and use its high-level methods to fill and
* read it. It will automatically handle shifting the buffer.
*/
class DecoderBuffer {
Decoder *const decoder;
InputStream &is;
DynamicFifoBuffer<uint8_t> buffer;
public:
/**
* Creates a new buffer.
*
* @param _decoder the decoder object, used for decoder_read(),
* may be nullptr
* @param _is the input stream object where we should read from
* @param _size the maximum size of the buffer
*/
DecoderBuffer(Decoder *_decoder, InputStream &_is,
size_t _size)
:decoder(_decoder), is(_is), buffer(_size) {}
const InputStream &GetStream() const {
return is;
}
void Clear() {
buffer.Clear();
}
/**
* Read data from the #InputStream and append it to the buffer.
*
* @return true if data was appended; false if there is no
* data available (yet), end of file, I/O error or a decoder
* command was received
*/
bool Fill();
/**
* How many bytes are stored in the buffer?
*/
gcc_pure
size_t GetAvailable() const {
return buffer.GetAvailable();
}
/**
* Reads data from the buffer. This data is not yet consumed,
* you have to call Consume() to do that. The returned buffer
* becomes invalid after a Fill() or a Consume() call.
*/
ConstBuffer<void> Read() const {
auto r = buffer.Read();
return { r.data, r.size };
}
/**
* Wait until this number of bytes are available. Returns nullptr on
* error.
*/
ConstBuffer<void> Need(size_t min_size);
/**
* Consume (delete, invalidate) a part of the buffer. The
* "nbytes" parameter must not be larger than the length
* returned by Read().
*
* @param nbytes the number of bytes to consume
*/
void Consume(size_t nbytes) {
buffer.Consume(nbytes);
}
/**
* Skips the specified number of bytes, discarding its data.
*
* @param nbytes the number of bytes to skip
* @return true on success, false on error
*/
bool Skip(size_t nbytes);
};
#endif
