From 6f095b91ce75d7aef43ba47976a4a3c9d8657b23 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Mon, 13 Feb 2023 17:04:13 -0700
Subject: [PATCH] tempo map: add data structure and methods for (fast?) lookup
 tables

As of this commit, none of the data structures are used.
---
 libs/temporal/tempo.cc         | 83 ++++++++++++++++++++++++++++++++++
 libs/temporal/temporal/tempo.h | 29 ++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/libs/temporal/tempo.cc b/libs/temporal/tempo.cc
index 0d0a3ed887..0df814cb45 100644
--- a/libs/temporal/tempo.cc
+++ b/libs/temporal/tempo.cc
@@ -3424,6 +3424,89 @@ TempoMap::write_copy()
 	return _map_mgr.write_copy();
 }
 
+void
+TempoMap::drop_lookup_table (){
+
+	superclock_beat_lookup_table.clear ();
+	beat_superclock_lookup_table.clear ();
+	beat_bbt_lookup_table.clear ();
+	superclock_bbt_lookup_table.clear ();
+}
+
+Temporal::Beats
+TempoMap::beat_lookup (superclock_t sc, bool& found) const
+{
+	LookupTable::const_iterator i = superclock_beat_lookup_table.find (sc);
+	if (i == superclock_beat_lookup_table.end()) {
+		found = false;
+		return Beats();;
+	}
+	found = true;
+	return Temporal::Beats::ticks (i->second);
+}
+
+superclock_t
+TempoMap::superclock_lookup (Temporal::Beats const & b, bool& found) const
+{
+	LookupTable::const_iterator i = beat_superclock_lookup_table.find (b.to_ticks());
+	if (i == beat_superclock_lookup_table.end()) {
+		found = false;
+		return 0;
+	}
+	found = true;
+	return i->second;
+}
+
+BBT_Time
+TempoMap::bbt_lookup (Temporal::Beats const & b, bool& found) const
+{
+	LookupTable::const_iterator i = beat_bbt_lookup_table.find (b.to_ticks());
+	if (i == beat_bbt_lookup_table.end()) {
+		found = false;
+		return BBT_Time ();
+	}
+	found = true;
+	return BBT_Time::from_integer (i->second);
+}
+
+BBT_Time
+TempoMap::bbt_lookup (superclock_t sc, bool& found) const
+{
+	LookupTable::const_iterator i = superclock_bbt_lookup_table.find (sc);
+	if (i == superclock_bbt_lookup_table.end()) {
+		found = false;
+		return BBT_Time ();
+	}
+	found = true;
+	return BBT_Time::from_integer (i->second);
+}
+
+/* see tempo.h comments about why this is const */
+void
+TempoMap::superclock_to_beat_store (superclock_t sc, Temporal::Beats const & b) const
+{
+	superclock_beat_lookup_table[sc] = b.to_ticks();
+}
+
+/* see tempo.h comments about why this is const */
+void
+TempoMap::beat_to_superclock_store (Temporal::Beats const & b, superclock_t sc) const
+{
+	beat_superclock_lookup_table[b.to_ticks()] = sc;
+}
+
+void
+TempoMap::superclock_to_bbt_store (superclock_t sc, BBT_Time const & bbt) const
+{
+	superclock_bbt_lookup_table[sc] = bbt.as_integer ();
+}
+
+void
+TempoMap::beat_to_bbt_store (Temporal::Beats const & b, BBT_Time const & bbt) const
+{
+	beat_bbt_lookup_table[b.to_ticks()] = bbt.as_integer ();
+}
+
 int
 TempoMap::update (TempoMap::WritableSharedPtr m)
 {
diff --git a/libs/temporal/temporal/tempo.h b/libs/temporal/temporal/tempo.h
index cf73c8a9ba..3545839dea 100644
--- a/libs/temporal/temporal/tempo.h
+++ b/libs/temporal/temporal/tempo.h
@@ -24,6 +24,7 @@
 #include <vector>
 #include <cmath>
 #include <exception>
+#include <unordered_map>
 
 #include <boost/intrusive/list.hpp>
 
@@ -1086,6 +1087,34 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 	int parse_tempo_state_3x (const XMLNode& node, LegacyTempoState& lts);
 	int parse_meter_state_3x (const XMLNode& node, LegacyMeterState& lts);
 	int set_state_3x (XMLNode const &);
+
+	typedef std::unordered_map<int64_t,int64_t> LookupTable;
+
+	mutable LookupTable superclock_beat_lookup_table;
+	mutable LookupTable beat_superclock_lookup_table;
+	mutable LookupTable beat_bbt_lookup_table;
+	mutable LookupTable superclock_bbt_lookup_table;
+
+	friend class TempoPoint;
+	friend class MeterPoint;
+	friend class TempoMetric;
+	Temporal::Beats beat_lookup (superclock_t, bool& found) const;
+	superclock_t superclock_lookup (Temporal::Beats const &, bool& found) const;
+
+	Temporal::BBT_Time bbt_lookup (superclock_t, bool & found) const;
+	Temporal::BBT_Time bbt_lookup (Temporal::Beats const & b, bool & found) const;
+
+	/* These are not really const, but the lookup tables are marked mutable
+	 * to allow time domain conversions to store their results while being
+	 * marked const (which is more semantically correct).
+	 */
+
+	void superclock_to_beat_store (superclock_t, Temporal::Beats const &) const;
+	void beat_to_superclock_store (Temporal::Beats const &, superclock_t) const;;
+	void beat_to_bbt_store (Temporal::Beats const &, Temporal::BBT_Time const &) const;;
+	void superclock_to_bbt_store (superclock_t, Temporal::BBT_Time const &) const;;
+
+	void drop_lookup_table ();
 };
 
 class LIBTEMPORAL_API TempoCommand : public Command {