Initial community commit

Src/external_dependencies/openmpt-trunk/mptrack/plugins/VstEventQueue.h

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+/*
+ * VstEventQueue.h
+ * ---------------
+ * Purpose: Event queue for VST events.
+ * Notes  : Modelled after an idea from https://www.kvraudio.com/forum/viewtopic.php?p=3043807#p3043807
+ * Authors: OpenMPT Devs
+ * The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
+ */
+
+
+#pragma once
+
+#include "openmpt/all/BuildSettings.hpp"
+
+#include <deque>
+#include "mpt/mutex/mutex.hpp"
+#include "VstDefinitions.h"
+
+OPENMPT_NAMESPACE_BEGIN
+
+class VstEventQueue : public Vst::VstEvents
+{
+protected:
+
+	// Although originally all event types were apparently supposed to be of the same size, this is not the case on 64-Bit systems.
+	// VstMidiSysexEvent contains 3 pointers, so the struct size differs between 32-Bit and 64-Bit systems.
+	union Event
+	{
+		Vst::VstEvent event;
+		Vst::VstMidiEvent midi;
+		Vst::VstMidiSysexEvent sysex;
+	};
+
+	// Here we store our events which are then inserted into the fixed-size event buffer sent to the plugin.
+	std::deque<Event> eventQueue;
+	// Since plugins can also add events to the queue (even from a different thread than the processing thread),
+	// we need to ensure that reading and writing is never done in parallel.
+	mpt::mutex criticalSection;
+
+public:
+
+	VstEventQueue()
+	{
+		numEvents = 0;
+		reserved = 0;
+		std::fill(std::begin(events), std::end(events), nullptr);
+	}
+
+	// Get the number of events that are currently queued, but not in the output buffer.
+	size_t GetNumQueuedEvents()
+	{
+		return eventQueue.size() - numEvents;
+	}
+
+	// Add a VST event to the queue. Returns true on success.
+	// Set insertFront to true to prioritise this event (i.e. add it at the front of the queue instead of the back)
+	bool Enqueue(const Vst::VstEvent *event, bool insertFront = false)
+	{
+		MPT_ASSERT(event->type != Vst::kVstSysExType || event->byteSize == sizeof(Vst::VstMidiSysexEvent));
+		MPT_ASSERT(event->type != Vst::kVstMidiType || event->byteSize == sizeof(Vst::VstMidiEvent));
+
+		Event copyEvent;
+		size_t copySize;
+		// randomid by Insert Piz Here sends events of type kVstMidiType, but with a claimed size of 24 bytes instead of 32.
+		// Hence, we enforce the size of known events.
+		if(event->type == Vst::kVstSysExType)
+			copySize = sizeof(Vst::VstMidiSysexEvent);
+		else if(event->type == Vst::kVstMidiType)
+			copySize = sizeof(Vst::VstMidiEvent);
+		else
+			copySize = std::min(size_t(event->byteSize), sizeof(copyEvent));
+		memcpy(&copyEvent, event, copySize);
+
+		if(event->type == Vst::kVstSysExType)
+		{
+			// SysEx messages need to be copied, as the space used for the dump might be freed in the meantime.
+			auto &e = copyEvent.sysex;
+			auto sysexDump = new (std::nothrow) std::byte[e.dumpBytes];
+			if(sysexDump == nullptr)
+				return false;
+			memcpy(sysexDump, e.sysexDump, e.dumpBytes);
+			e.sysexDump = sysexDump;
+		}
+
+		mpt::lock_guard<mpt::mutex> lock(criticalSection);
+		if(insertFront)
+			eventQueue.push_front(copyEvent);
+		else
+			eventQueue.push_back(copyEvent);
+		return true;
+	}
+
+	// Set up the queue for transmitting to the plugin. Returns number of elements that are going to be transmitted.
+	int32 Finalise()
+	{
+		mpt::lock_guard<mpt::mutex> lock(criticalSection);
+		numEvents = static_cast<int32>(std::min(eventQueue.size(), MAX_EVENTS));
+		for(int32 i = 0; i < numEvents; i++)
+		{
+			events[i] = &eventQueue[i].event;
+		}
+		return numEvents;
+	}
+
+	// Remove transmitted events from the queue
+	void Clear()
+	{
+		mpt::lock_guard<mpt::mutex> lock(criticalSection);
+		if(numEvents)
+		{
+			// Release temporarily allocated buffer for SysEx messages
+			for(auto e = eventQueue.begin(); e != eventQueue.begin() + numEvents; ++e)
+			{
+				if(e->event.type == Vst::kVstSysExType)
+				{
+					delete[] e->sysex.sysexDump;
+				}
+			}
+			eventQueue.erase(eventQueue.begin(), eventQueue.begin() + numEvents);
+			numEvents = 0;
+		}
+	}
+
+};
+
+OPENMPT_NAMESPACE_END