inline uint64_t nrf5AlarmGetCurrentTime()
{
uint32_t rtcValue1;
uint32_t rtcValue2;
uint32_t offset;
rtcValue1 = nrf_rtc_counter_get(RTC_INSTANCE);
__DMB();
offset = sTimeOffset;
__DMB();
rtcValue2 = nrf_rtc_counter_get(RTC_INSTANCE);
if ((rtcValue2 < rtcValue1) || (rtcValue1 == 0))
{
// Overflow detected. Additional condition (rtcValue1 == 0) covers situation when overflow occurred in
// interrupt state, before this function was entered. But in general, this function shall not be called
// from interrupt other than alarm interrupt.
// Wait at least 20 cycles, to ensure that if interrupt is going to be called, it will be called now.
for (uint32_t i = 0; i < 4; i++)
{
__NOP();
__NOP();
__NOP();
}
// If the event flag is still on, it means that the interrupt was not called, as we are in interrupt state.
if (nrf_rtc_event_pending(RTC_INSTANCE, NRF_RTC_EVENT_OVERFLOW))
{
HandleOverflow();
}
offset = sTimeOffset;
}
return US_PER_MS * (uint64_t)offset + TicksToTime(rtcValue2);
}
CMIDISource::CMIDISource(CMediaSource *pSource, int nIndex) : CMediaSource(pSource, nIndex)
{
char str[5];
int i;
StreamPos *pPos;
MIDITrack *pTrack;
TempoEvent *pEvent;
unsigned char pData[1024];
int nSize;
m_pStreamPos = NULL;
m_pTracks = NULL;
m_pTempoEvents = NULL;
m_nDuration = 0;
str[4] = '\0';
SourceReadData(str, 4);
if (strcmp(str, "MThd") != 0)
return;
if (SourceReadBigEndian(4) != 6) //header length
return;
m_MIDIInfo.nFormat = SourceReadBigEndian(2);
m_nOutputNum = SourceReadBigEndian(2); //number of track
m_nTicksPerQuarterNote = SourceReadBigEndian(2);
m_pStreamPos = new StreamPos[m_nOutputNum];
m_pTracks = new MIDITrack[m_nOutputNum];
for (i = 0; i < m_nOutputNum; i++)
{
pPos = m_pStreamPos + i;
SourceReadData(str, 4); //track id
pPos->nSize = SourceReadBigEndian(4); //track length
if (strcmp(str, "MTrk") == 0)
pPos->nHeadPos = SourceGetPosition();
else
pPos->nHeadPos = 0; //invalid track
SourceSeekData(pPos->nSize, SEEK_CUR); //skip to next track
}
if (m_nOutputNum == 0)
return;
pTrack = m_pTracks; //first track;
m_pTempoEvents = new TempoEvent[m_pStreamPos[0].nSize / 6]; //minimum size of a change tempo event is 6
m_nTempoEventNum = 1;
pEvent = m_pTempoEvents;
pEvent->nTempo = 500000; //default tempo in microseconds per quarter note
pEvent->nTicks = 0;
pEvent->nTime = 0;
SeekTime(0);
for (;;)
{
nSize = ReadData(0, pData, sizeof(pData));
if (nSize == 0)
break;
if (pData[0] == 0xFF && pData[1] == 0x51) //set tempo
{
pEvent = m_pTempoEvents + m_nTempoEventNum;
pEvent->nTempo = (pData[2] << 16) | (pData[3] << 8) | pData[4]; //microseconds per quarter note
pEvent->nTicks = pTrack->nTicks;
pEvent->nTime = TicksToTime(pTrack->nTicks);
++m_nTempoEventNum;
}
}
m_nDuration = m_pStreamPos[0].nTime;
for (i = 1; i < m_nOutputNum; i++) //for each track except the first one
{
do
{
nSize = ReadData(i, pData, sizeof(pData));
} while (nSize > 0); //until the last event of this track
if (m_pStreamPos[i].nTime > m_nDuration)
m_nDuration = m_pStreamPos[i].nTime;
}
SeekTime(0);
}
int CMIDISource::ReadData(int nIndex, void *pData, int nSize)
{
StreamPos *pPos;
unsigned char *pBuffer;
MIDITrack *pTrack;
int nStatus;
int nValue;
if (nIndex >= m_nOutputNum)
return 0;
pPos = m_pStreamPos + nIndex;
if (pPos->nHeadPos == 0) //invalid track
return 0;
if (pPos->nRelPos >= pPos->nSize)
return 0;
SourceSeekData(pPos->nAbsPos, SEEK_SET);
pBuffer = (unsigned char *)pData;
pTrack = m_pTracks + nIndex;
pTrack->nTicks += ReadVarLen(); //delta time
nStatus = SourceReadData();
if (nStatus >= 0xF0 && nStatus < 0xFF) //system exclusive event
{
pBuffer[0] = nStatus;
nValue = ReadVarLen();
SourceReadData(pBuffer + 1, nValue);
assert(nSize >= 1 + nValue);
if (nSize > 1 + nValue)
nSize = 1 + nValue;
}
else
{
if ((nStatus & 0x80) == 0) //running status
{
pBuffer[0] = pTrack->nStatus;
pBuffer[1] = nStatus;
}
else //MIDI event or meta event
{
pTrack->nStatus = nStatus;
pBuffer[0] = nStatus;
pBuffer[1] = SourceReadData();
}
switch (pBuffer[0] & 0xF0)
{
case 0x80:
case 0x90:
case 0xA0:
case 0xB0:
case 0xE0:
pBuffer[2] = SourceReadData();
nSize = 3;
break;
case 0xC0:
case 0xD0:
nSize = 2;
break;
case 0xF0:
nValue = ReadVarLen(); //data length
SourceReadData(pBuffer + 2, nValue);
assert(nSize >= 2 + nValue);
if (nSize > 2 + nValue)
nSize = 2 + nValue;
break;
default:
nSize = 0;
break;
} //switch
} //else
pPos->nAbsPos = SourceGetPosition();
pPos->nRelPos = pPos->nAbsPos - pPos->nHeadPos;
pPos->nTime = TicksToTime(pTrack->nTicks);
if (pPos->nTime < m_nSeekTime) //event before seektime
{
pPos->nTime = 0; //render immediately
if (pBuffer[0] >= 0x80 && pBuffer[0] <= 0x9F) //note on or note off
pBuffer[0] = 0x00; //invalid event, should not be renderered
}
return nSize;
}
