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diff --git a/src/sound/AudioCache.h b/src/sound/AudioCache.h
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+// -*- c-basic-offset: 4 -*-
+
+/*
+    Rosegarden
+    A sequencer and musical notation editor.
+
+    This program is Copyright 2000-2008
+        Guillaume Laurent   <[email protected]>,
+        Chris Cannam        <[email protected]>,
+        Richard Bown        <[email protected]>
+
+    The moral right of the authors to claim authorship of this work
+    has been asserted.
+
+    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.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef _AUDIO_CACHE_H_
+#define _AUDIO_CACHE_H_
+
+#include <map>
+
+namespace Rosegarden
+{
+
+/**
+ * A simple cache for smallish bits of audio data, indexed by some
+ * opaque pointer type.  (The PlayableAudioFile uses this with an
+ * AudioFile* index type, for example.)  With reference counting.
+ */
+
+class AudioCache
+{
+public:
+    AudioCache() { }
+    virtual ~AudioCache();
+
+    /**
+     * Look some audio data up in the cache and report whether it
+     * exists.
+     */
+    bool has(void *index);
+
+    /**
+     * Look some audio data up in the cache and return it if it
+     * exists, returning the number of channels in channels, the frame
+     * count in frames, and one pointer per channel to samples in the
+     * return value.  Return 0 if the data is not in cache.  Does not
+     * affect the reference count.  Ownership of the returned data
+     * remains with the cache object.  You should not call this unless
+     * you have already called incrementReference (or addData) to
+     * register your interest.
+     */
+    float **getData(void *index, size_t &channels, size_t &frames);
+
+    /**
+     * Add a piece of data to the cache, and increment the reference
+     * count for that data (to 1).  Ownership of the data is passed
+     * to the cache, which will delete it with delete[] when done.
+     */
+    void addData(void *index, size_t channels, size_t nframes, float **data);
+
+    /**
+     * Increment the reference count for a given piece of data.
+     */
+    void incrementReference(void *index);
+
+    /**
+     * Decrement the reference count for a given piece of data,
+     * and delete the data from the cache if the reference count has
+     * reached zero.
+     */
+    void decrementReference(void *index);
+
+protected:
+    void clear();
+
+    struct CacheRec {
+        CacheRec() : data(0), channels(0), nframes(0), refCount(0) { }
+        CacheRec(float **d, size_t c, size_t n) :
+            data(d), channels(c), nframes(n), refCount(1) { }
+        ~CacheRec();
+        float **data;
+        size_t channels;
+        size_t nframes;
+        int refCount;
+    };
+
+    std::map<void *, CacheRec *> m_cache;
+};
+
+}
+
+#endif