1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
2 
3 /*
4     Rosegarden
5     A sequencer and musical notation editor.
6     Copyright 2000-2021 the Rosegarden development team.
7     See the AUTHORS file for more details.
8 
9     This program is free software; you can redistribute it and/or
10     modify it under the terms of the GNU General Public License as
11     published by the Free Software Foundation; either version 2 of the
12     License, or (at your option) any later version.  See the file
13     COPYING included with this distribution for more information.
14 */
15 
16 #ifndef RG_AUDIO_CACHE_H
17 #define RG_AUDIO_CACHE_H
18 
19 #include <map>
20 #include <stddef.h>
21 
22 namespace Rosegarden
23 {
24 
25 /**
26  * A simple cache for smallish bits of audio data, indexed by some
27  * opaque pointer type.  (The PlayableAudioFile uses this with an
28  * AudioFile* index type, for example.)  With reference counting.
29  */
30 
31 class AudioCache
32 {
33 public:
34     AudioCache() { }
35     virtual ~AudioCache();
36 
37     /**
38      * Look some audio data up in the cache and report whether it
39      * exists.
40      */
41     bool has(void *index);
42 
43     /**
44      * Look some audio data up in the cache and return it if it
45      * exists, returning the number of channels in channels, the frame
46      * count in frames, and one pointer per channel to samples in the
47      * return value.  Return 0 if the data is not in cache.  Does not
48      * affect the reference count.  Ownership of the returned data
49      * remains with the cache object.  You should not call this unless
50      * you have already called incrementReference (or addData) to
51      * register your interest.
52      */
53     float **getData(void *index, size_t &channels, size_t &frames);
54 
55     /**
56      * Add a piece of data to the cache, and increment the reference
57      * count for that data (to 1).  Ownership of the data is passed
58      * to the cache, which will delete it with delete[] when done.
59      */
60     void addData(void *index, size_t channels, size_t nframes, float **data);
61 
62     /**
63      * Increment the reference count for a given piece of data.
64      */
65     void incrementReference(void *index);
66 
67     /**
68      * Decrement the reference count for a given piece of data,
69      * and delete the data from the cache if the reference count has
70      * reached zero.
71      */
72     void decrementReference(void *index);
73 
74 protected:
75     void clear();
76 
77     struct CacheRec {
78         CacheRec() : data(nullptr), channels(0), nframes(0), refCount(0) { }
79         CacheRec(float **d, size_t c, size_t n) :
80             data(d), channels(c), nframes(n), refCount(1) { }
81         ~CacheRec();
82         float **data;
83         size_t channels;
84         size_t nframes;
85         int refCount;
86     };
87 
88     std::map<void *, CacheRec *> m_cache;
89 };
90 
91 }
92 
93 #endif
94