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+/*
+ * Copyright (C) 2003-2014 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