reimplement RTMidiBuffer using a highly optimized data structure

Reduces load time of Glass MIDI piece with 48k note events by about 35%. Improves data
locality. Omits size for all 3 byte or less MIDI events, uses implicit size. No limit
on size of sysex.

Relies on the fact that the data structure is always filled linearly in time, and
never modified.

1 files changed, 28 insertions, 4 deletions

diff --git a/libs/ardour/ardour/rt_midibuffer.h b/libs/ardour/ardour/rt_midibuffer.h
index 28d6e69233..da2c5c0e05 100644
--- a/libs/ardour/ardour/rt_midibuffer.h
+++ b/libs/ardour/ardour/rt_midibuffer.h
@@ -43,7 +43,7 @@ class LIBARDOUR_API RTMidiBuffer : public Evoral::EventSink<samplepos_t>
 	RTMidiBuffer (size_t capacity);
 	~RTMidiBuffer();
 
-	void clear() { _size = 0; }
+	void clear();
 	void resize(size_t);
 	size_t size() const { return _size; }
 
@@ -52,12 +52,36 @@ class LIBARDOUR_API RTMidiBuffer : public Evoral::EventSink<samplepos_t>
 
 	void dump (uint32_t);
 
+	struct Item {
+		samplepos_t timestamp;
+		union {
+			uint8_t  bytes[4];
+			uint32_t offset;
+		};
+	};
+
   private:
+
+	struct Blob {
+		uint32_t size;
+		uint8_t data[0];
+	};
+
+	/* The main store. Holds Items (timestamp+up to 3 bytes of data OR
+	 * offset into secondary storage below)
+	 */
+
 	size_t _size;
 	size_t _capacity;
-	uint8_t* _data; ///< event data
-	typedef std::multimap<TimeType,size_t> Map;
-	Map _map;
+	Item*  _data;
+
+	/* secondary blob storage. Holds Blobs (arbitrary size + data) */
+
+	uint32_t alloc_blob (uint32_t size);
+	uint32_t store_blob (uint32_t size, uint8_t const * data);
+	uint32_t _pool_size;
+	uint32_t _pool_capacity;
+	uint8_t* _pool;
 };
 
 } // namespace ARDOUR