Start midi file processing.

src/audio/midi/MidiReader.cpp

@@ -0,0 +1,211 @@
+#include "MidiReader.h"
+#include <fstream>
+#include <iostream>
+#include <cstring>
+#include <bitset>
+#include "MidiDocument.h"
+#include "ByteUtils.h"
+#include "MidiTrack.h"
+
+MidiReader::MidiReader()
+{
+
+}
+
+bool GetBytes(std::ifstream& file, char* buffer, unsigned number)
+{
+	char c;
+	for(unsigned idx=0; idx<number; idx++)
+	{
+		if(file.get(c))
+		{
+			buffer[idx] = c;
+		}
+		else
+		{
+			return false;
+		}
+	}
+	return true;
+}
+
+bool GetWord(std::ifstream& file, char* buffer)
+{
+	return GetBytes(file, buffer, 2);
+}
+
+bool GetDWord(std::ifstream& file, char* buffer)
+{
+	return GetBytes(file, buffer, 4);
+}
+
+bool MidiReader::ProcessHeader(std::ifstream& file)
+{
+	char c;
+	unsigned bufferSize = ByteUtils::BYTES_PER_DWORD;
+	char buffer[bufferSize];
+
+	if(!GetDWord(file, buffer))
+	{
+		return false;
+	}
+
+	if(!ByteUtils::CompareDWords(buffer, HeaderLabel))
+	{
+		return false;
+	}
+
+	if(!GetDWord(file, buffer))
+	{
+		return false;
+	}
+
+	int length = ByteUtils::ToDWord(buffer);
+
+    if(!GetWord(file, buffer))
+	{
+    	return false;
+	}
+	mDocument.mFormatType = ByteUtils::ToWord(buffer);
+
+    if(!GetWord(file, buffer))
+    {
+    	return false;
+    }
+	mDocument.mExpectedTracks = ByteUtils::ToWord(buffer);
+
+    if(!GetWord(file, buffer))
+    {
+    	return false;
+    }
+	int time_division;
+    std::memcpy(&time_division, buffer, sizeof(int));
+
+	const int TOP_7_BITS = 0x7F00; // 0111 1111 - 0000 0000
+	mDocument.mUseFps = ByteUtils::GetWordFirstBit(time_division);
+	mDocument.mFps = ((~time_division & TOP_7_BITS) >> 8) - 1; // Reverse 2complement of next 7 bits
+	mDocument.ticksPerFrame = ByteUtils::GetWordLastByte(time_division);
+	return true;
+}
+
+int MidiReader::ProcessTimeDelta(std::ifstream& file)
+{
+	char c;
+	file.get(c);
+	bool needs_next = c & ByteUtils::BYTE_FIRST_BIT;
+	int time_offset = 0;
+	if(!needs_next)
+	{
+		time_offset = int(c);
+		mTrackByteCount ++;
+	}
+	std::cout << "Next " << needs_next <<std::endl;
+	std::cout << "Offset " << time_offset <<std::endl;
+	return time_offset;
+}
+
+bool MidiReader::ProcessMetaEvent(std::ifstream& file, MetaMidiEvent& event)
+{
+	char c;
+	file.get(c);
+	mTrackByteCount ++;
+	if(MetaMidiEvent::IsTrackName(c))
+	{
+		event.mType = MetaMidiEvent::Type::TRACK_NAME;
+		file.get(c);
+		mTrackByteCount ++;
+		int length = int(c);
+		std::string name;
+		std::cout << "Track name: " << length <<std::endl;
+
+		for(unsigned idx=0; idx<length; idx++)
+		{
+			file.get(c);
+			mTrackByteCount ++;
+			name += c;
+		}
+		std::cout << name << std::endl;
+		event.mLabel = "Track name";
+	}
+	else
+	{
+		std::cout << "something else" << std::endl;
+		std::cout << "Next " << std::bitset<8>(c) << "|"  <<std::endl;
+	}
+	return true;
+}
+
+bool MidiReader::ProcessEvent(std::ifstream& file)
+{
+	char c;
+	int timeDelta = ProcessTimeDelta(file);
+
+	file.get(c);
+	mTrackByteCount ++;
+	if(MidiEvent::IsMetaEvent(c))
+	{
+		MetaMidiEvent event;
+		event.mTimeDelta = timeDelta;
+		std::cout << "Meta event " <<std::endl;
+		ProcessMetaEvent(file, event);
+	}
+	else
+	{
+		int first_byte = 0xF0;
+		int event_type = (c & first_byte) >> 4;
+		std::cout << "Next " << std::bitset<8>(c) << "|" << event_type <<std::endl;
+		std::cout << event_type << std::endl;
+	}
+	return true;
+}
+
+bool MidiReader::ProcessTrackChunk(std::ifstream& file)
+{
+	char c;
+	unsigned bufferSize = ByteUtils::BYTES_PER_DWORD;
+	char buffer[bufferSize];
+
+	if(!GetDWord(file, buffer))
+	{
+		return false;
+	}
+
+	if(!ByteUtils::CompareDWords(buffer, TrackChunkLabel))
+	{
+		return false;
+	}
+
+	if(!GetDWord(file, buffer))
+	{
+		return false;
+	}
+	int chunkSize = ByteUtils::ToDWord(buffer);
+	std::cout << "Chunk size: "<< chunkSize << std::endl;
+
+	mTrackByteCount = 0;
+	MidiTrack track;
+	ProcessEvent(file);
+	std::cout << "Track byte count: "<< mTrackByteCount << std::endl;
+
+	ProcessEvent(file);
+
+	mDocument.mTracks.push_back(track);
+	return true;
+}
+
+void MidiReader::Read(const std::string& path)
+{
+	std::ifstream file(path);
+	if(!ProcessHeader(file))
+	{
+		std::cout << "Problem processing header" << std::endl;
+	}
+
+	if(!ProcessTrackChunk(file))
+	{
+		std::cout << "Problem processing track chunk" << std::endl;
+	}
+
+
+	file.close();
+}