rtmidi/Message.cpp

#include <vector>
#include <iostream>
#include "Message.h"

namespace midi {

Message* Message::parse(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 "Message::parseMessage() does not support system messages yet.";
	}
	else
	{
		// channel message
		unsigned char channel = messageBytes[0] & 0xF;

		switch(messageType)
		{
			case NoteOnMessage::messageType:
			case NoteOffMessage::messageType:
			{
				unsigned char pitch = messageBytes[1];
				unsigned char velocity = messageBytes[2];
				if(messageType == NoteOffMessage::messageType || velocity == 0)
				{
					return new NoteOffMessage(channel, pitch, velocity);
				}
				else
				{
					return new NoteOnMessage(channel, pitch, velocity);
				}
			}
			case ControlChangeMessage::messageType:
				return new ControlChangeMessage(channel, messageBytes[1], messageBytes[2]);
			case ProgramChangeMessage::messageType:
				return new ProgramChangeMessage(channel, messageBytes[1]);
			case PitchBendChangeMessage::messageType:
				// 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 "Message::parseMessage() does not support the given type of channel message yet.";
		}
	}
}

std::vector<unsigned char> NoteOnMessage::getBytes() const
{
	std::vector<unsigned char> bytes(3);
	bytes[0] = messageType << 4 | channel;
	bytes[1] = pitch;
	bytes[2] = velocity;
	return bytes;
}

std::vector<unsigned char> NoteOffMessage::getBytes() const
{
	std::vector<unsigned char> bytes(3);
	bytes[0] = messageType << 4 | channel;
	bytes[1] = pitch;
	bytes[2] = velocity;
	return bytes;
}

std::vector<unsigned char> ControlChangeMessage::getBytes() const
{
	std::vector<unsigned char> bytes(3);
	bytes[0] = messageType << 4 | channel;
	bytes[1] = control;
	bytes[2] = value;
	return bytes;
}

std::vector<unsigned char> ProgramChangeMessage::getBytes() const
{
	std::vector<unsigned char> bytes(2);
	bytes[0] = messageType << 4 | channel;
	bytes[1] = program;
	return bytes;
}

std::vector<unsigned char> PitchBendChangeMessage::getBytes() const
{
	std::vector<unsigned char> bytes(3);
	bytes[0] = messageType << 4 | channel;
	// bytes[1] are the seven least significant bits. 
	// bytes[2] are the seven most significant bits.
	bytes[1] = value & ((1 << 7) - 1);
	bytes[2] = value >> 7;
	return bytes;
}

std::ostream& operator<<(std::ostream& stream, const Message& 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"; 
}

} // namespace