/* Get a short from the byte buffer */
int BbGetShort(PBYTE_BUFFER buff, short *s) {
if (buff->position + sizeof(*s) >= buff->length) {
return 0;
}
memcpy(s, &buff->buffer[buff->position], sizeof(*s));
buff->position += sizeof(*s);
*s = byteSwapShort(buff, *s);
return 1;
}
/* Put a short into the byte buffer */
int BbPutShort(PBYTE_BUFFER buff, short s) {
if (buff->position + sizeof(s) > buff->length) {
return 0;
}
s = byteSwapShort(buff, s);
memcpy(&buff->buffer[buff->position], &s, sizeof(s));
buff->position += sizeof(s);
return 1;
}
int MIDIFile::initMIDIFile(const char* _fileName)
{
m_pFileBuf = loadFile(_fileName, m_fileSize);
if (!m_pFileBuf)
{
printf("something went wrong during file load.\n");
return 1;
}
//1: process header
m_pHeader = (MIDIHeaderInfo*)m_pFileBuf;
int numTracks = byteSwapShort(m_pHeader->tracks);
m_PulsesPerQuarterNote = byteSwapShort(m_pHeader->ticks);
//2: process body
unsigned char* pBody = m_pFileBuf += sizeof(MIDIHeaderInfo);
auto pCurrentTrack = (char*) pBody;
auto pCurrentTrackInfo = (MIDITrackInfo*)pCurrentTrack;
for (int i = 0; i < numTracks; i++)
{
if (pCurrentTrackInfo->id != 0x6b72544d)//magic number: 0xkrTM -> big endian MTrk
{
printf("Fatal Error: MTrk identifier not found when parsing file: %s\n", _fileName);
return 1;
}
MIDITrack currentTrack;
currentTrack.m_pTrackInfo = pCurrentTrackInfo;
currentTrack.m_pBuffer = (unsigned char*)pCurrentTrack + sizeof(MIDITrackInfo);
currentTrack.m_absTime = 0;
currentTrack.m_lastEvent = 0;
m_tracks.push_back(currentTrack);
//increment pCurrentTrack to point to the next track
pCurrentTrack += sizeof(MIDITrackInfo) + byteSwapInt(m_tracks[i].m_pTrackInfo->length);
}
return 0;
}
