rtmidi/MidiMessage.cpp

#include <vector>
#include "RtMidi.h" // RtMidiError
#include "MidiMessage.h"

MidiMessage* MidiMessage::parseMessage(std::vector<unsigned char> &messageBytes)
{
	// msg[0] has 8 bits                                                                        
    //	- 4 higher significant bits: message type
    //	- 4 lower significant bits: channel (0 - 15)
	unsigned char messageType = messageBytes[0] >> 4;
	if(messageType == 0xF) 
	{
		// system message
		throw RtMidiError("MidiMessage::parseMessage() does not support system messages yet.", RtMidiError::DEBUG_WARNING);
	}
	else
	{
		// channel message
		unsigned char channel = messageBytes[0] & 0xF;

		switch(messageType)
		{
			case 0x8:
			case 0x9:
			{
				unsigned char pitch = messageBytes[1];
				unsigned char velocity = messageBytes[2];
				if(messageType == 0x8 || velocity == 0)
				{
					return new NoteOffMessage(channel, pitch, velocity);
				}
				else
				{
					return new NoteOnMessage(channel, pitch, velocity);
				}
			}
			case 0xB:
				return new ControlChangeMessage(channel, messageBytes[1], messageBytes[2]);
			case 0xC:
				return new ProgramChangeMessage(channel, messageBytes[1]);
			case 0xE:
				// messageBytes[1] are the least significant 7 bits. 
				// messageBytes[2] are the most significant 7 bits.
				return new PitchBendChangeMessage(
					channel, 
					(messageBytes[2] << 7) + messageBytes[1]
					);
			default:
				throw RtMidiError(
					"MidiMessage::parseMessage() does not support the given type of channel message yet.", 
					RtMidiError::DEBUG_WARNING
					);
		}
	}
}

std::ostream& operator<<(std::ostream& stream, const MidiMessage& message)
{
	message.print(stream);
	return stream;
}

void NoteOnMessage::print(std::ostream& stream) const
{
	stream	<< "channel #" << (unsigned short)(channel + 1) << ": "
			<< "note " << (unsigned short)pitch << " with velocity " << (unsigned short)velocity << " on\n"; 
}

void NoteOffMessage::print(std::ostream& stream) const
{
	stream	<< "channel #" << (unsigned short)(channel + 1) << ": "
			<< "note " << (unsigned short)pitch << " off\n"; 
}

void ControlChangeMessage::print(std::ostream& stream) const
{
	stream	<< "channel #" << (unsigned short)(channel + 1) << ": "
			<< "change value of control #" << (unsigned short)(control + 1)
			<< " to " << (unsigned short)value << "\n"; 
}

void ProgramChangeMessage::print(std::ostream& stream) const
{
	stream	<< "channel #" << (unsigned short)(channel + 1) << ": "
			<< "switch to program # " << (unsigned short)(program + 1) << "\n"; 
}

void PitchBendChangeMessage::print(std::ostream& stream) const
{
	stream	<< "channel #" << (unsigned short)(channel + 1) << ": "
			<< "pitch bended to " << value << "\n"; 
}