1 files changed, 117 insertions, 0 deletions
diff --git a/src/decoder/DecoderBuffer.hxx b/src/decoder/DecoderBuffer.hxx
new file mode 100644
index 000000000..9cf47d915
--- /dev/null
+++ b/src/decoder/DecoderBuffer.hxx
@@ -0,0 +1,117 @@
+/*
+ * 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