From 2b754568a00cdc88e15cb57edbfb335891fcb775 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Sun, 24 Oct 2021 09:26:35 -0600
Subject: [PATCH] changes/extensions to RTMidiBuffer API to make it more
 suitable for slots/triggers

---
 libs/ardour/ardour/rt_midibuffer.h | 36 +++++++++++++++++++++++++----
 libs/ardour/rt_midibuffer.cc       | 37 ++++++++++++++++++++++--------
 2 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/libs/ardour/ardour/rt_midibuffer.h b/libs/ardour/ardour/rt_midibuffer.h
index 0f379b2dce..fcc6e9b1ab 100644
--- a/libs/ardour/ardour/rt_midibuffer.h
+++ b/libs/ardour/ardour/rt_midibuffer.h
@@ -29,6 +29,8 @@
 
 #include "evoral/Event.h"
 #include "evoral/EventSink.h"
+#include "evoral/midi_util.h"
+
 #include "ardour/types.h"
 
 namespace ARDOUR {
@@ -39,6 +41,12 @@ class MidiStateTracker;
 /**  */
 class LIBARDOUR_API RTMidiBuffer : public Evoral::EventSink<samplepos_t>
 {
+  private:
+	struct Blob {
+		uint32_t size;
+		uint8_t data[0];
+	};
+
   public:
 	typedef samplepos_t TimeType;
 
@@ -48,6 +56,9 @@ class LIBARDOUR_API RTMidiBuffer : public Evoral::EventSink<samplepos_t>
 	void clear();
 	void resize(size_t);
 	size_t size() const { return _size; }
+	bool empty() const { return _size == 0; }
+
+	samplecnt_t span() const;
 
 	uint32_t write (TimeType time, Evoral::EventType type, uint32_t size, const uint8_t* buf);
 	uint32_t read (MidiBuffer& dst, samplepos_t start, samplepos_t end, MidiStateTracker& tracker, samplecnt_t offset = 0);
@@ -64,14 +75,29 @@ class LIBARDOUR_API RTMidiBuffer : public Evoral::EventSink<samplepos_t>
 		};
 	};
 
+	Item const & operator[](size_t n) const {
+		if (n >= _size) {
+			throw std::exception ();
+		}
+		return _data[n];
+	}
+
+	uint8_t const * bytes (Item const & item, uint32_t& size) {
+		if (item.bytes[0]) {
+			size = Evoral::midi_event_size (item.bytes[1]);
+			return item.bytes;
+		} else {
+			uint32_t offset = item.offset & ~(1<<(CHAR_BIT-1));
+			Blob* blob = reinterpret_cast<Blob*> (&_pool[offset]);
+
+			size = blob->size;
+			return blob->data;
+		}
+	}
+
   private:
 	friend struct WriteProtectRender;
 
-	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)
 	 */
diff --git a/libs/ardour/rt_midibuffer.cc b/libs/ardour/rt_midibuffer.cc
index 2e92c44647..85f5f4c7cd 100644
--- a/libs/ardour/rt_midibuffer.cc
+++ b/libs/ardour/rt_midibuffer.cc
@@ -24,8 +24,6 @@
 #include "pbd/error.h"
 #include "pbd/debug.h"
 
-#include "evoral/midi_util.h"
-
 #include "ardour/debug.h"
 #include "ardour/midi_buffer.h"
 #include "ardour/midi_state_tracker.h"
@@ -194,8 +192,12 @@ RTMidiBuffer::write (TimeType time, Evoral::EventType /*type*/, uint32_t size, c
 {
 	/* This buffer stores only MIDI, we don't care about the value of "type" */
 
-	if (_size == _capacity) {
-		resize (_capacity + 1024); // XXX 1024 is completely arbitrary
+	if (_size + size >= _capacity) {
+		if (size > 1024) {
+			resize (_capacity + size + 1024); // XXX 1024 is completely arbitrary
+		} else {
+			resize (_capacity + 1024); // XXX 1024 is completely arbitrary
+		}
 	}
 
 	_data[_size].timestamp = time;
@@ -232,13 +234,15 @@ RTMidiBuffer::write (TimeType time, Evoral::EventType /*type*/, uint32_t size, c
 	return size;
 }
 
-/* These (non-matching) comparison arguments weren't supported prior to C99 !!!
+/* requires C++20 to be usable */
+/*
 static
 bool
-item_timestamp_earlier (ARDOUR::RTMidiBuffer::Item const & item, samplepos_t time)
+item_timestamp_earlier (ARDOUR::RTMidiBuffer::Item const & item, samplepos_t const & time)
 {
 	return item.timestamp < time;
-}*/
+}
+*/
 
 static
 bool
@@ -260,9 +264,8 @@ RTMidiBuffer::read (MidiBuffer& dst, samplepos_t start, samplepos_t end, MidiSta
 	Item foo;
 	Item* iend;
 	Item* item;
-
-	uint32_t count = 0;
 	foo.timestamp = start;
+	uint32_t count = 0;
 
 	if (start < end) {
 		iend = _data+_size;
@@ -271,7 +274,7 @@ RTMidiBuffer::read (MidiBuffer& dst, samplepos_t start, samplepos_t end, MidiSta
 	} else {
 		iend = _data;
 		--iend; /* yes, this is technically "illegal" but we will never indirect */
-		Item* uend = _data+_size;
+		Item* uend = _data + _size;
 		item = upper_bound (_data, uend, foo, item_item_earlier);
 
 		if (item == uend) {
@@ -412,3 +415,17 @@ RTMidiBuffer::clear ()
 	/* rendering new data .. it will not be reversed */
 	_reversed = false;
 }
+
+samplecnt_t
+RTMidiBuffer::span() const
+{
+	if (_size == 0 || _size == 1) {
+		return 0;
+	}
+
+	const Item* last = &_data[_size-1];
+	const Item* first = &_data[0];
+
+	return last->timestamp - first->timestamp;
+}
+