libcm/cmMidiFile.c

#include "cmPrefix.h"
#include "cmGlobal.h"
#include "cmRpt.h"
#include "cmErr.h"
#include "cmCtx.h"
#include "cmFile.h"
#include "cmMem.h"
#include "cmMallocDebug.h"
#include "cmLinkedHeap.h"
#include "cmMidi.h"
#include "cmMidiFile.h"

#ifdef cmBIG_ENDIAN
#define mfSwap16(v)  (v)
#define mfSwap32(v)  (v)
#else
#define mfSwap16(v)  cmSwap16(v)
#define mfSwap32(v)  cmSwap32(v)
#endif



typedef struct
{
  unsigned          cnt;   // count of track records
  cmMidiTrackMsg_t* base;  // pointer to first track recd
  cmMidiTrackMsg_t* last;  // pointer to last track recd
} _cmMidiTrack_t;

typedef struct
{
  cmErr_t            err;                // this objects error object
  cmLHeapH_t         lhH;                // linked heap used for all dynamically alloc'd data space
  cmFileH_t          fh;                 // cmFile handle (only used in fmMidiFileOpen())
  unsigned short     fmtId;              // midi file type id: 0,1,2
  unsigned short     ticksPerQN;         // ticks per quarter note or 0 if smpteFmtId is valid
  cmMidiByte_t       smpteFmtId;         // smpte format or 0 if ticksPerQN is valid
  cmMidiByte_t       smpteTicksPerFrame; // smpte ticks per frame or 0 if ticksPerQN is valid
  unsigned short     trkN;               // track count
  _cmMidiTrack_t*    trkV;               // track vector
  char*              fn;                 // file name or NULL if this object did not originate from a file
  unsigned           msgN;               // count of msg's in msgV[]
  cmMidiTrackMsg_t** msgV;               // sorted msg list
  
} _cmMidiFile_t;

#define _cmMidiFileError( err, rc ) _cmMidiFileOnError(err, rc, __LINE__,__FILE__,__FUNCTION__ )

cmMidiFileH_t cmMidiFileNullHandle = cmSTATIC_NULL_HANDLE;

cmMfRC_t _cmMidiFileOnError( cmErr_t* err, cmMfRC_t rc, int line, const char* fn, const char* func )
{
  return cmErrMsg(err,rc,"rc:%i line:%i %s %s\n",rc,line,func,fn);
}

_cmMidiFile_t* _cmMidiFileHandleToPtr( cmMidiFileH_t h )
{
  _cmMidiFile_t* p = (_cmMidiFile_t*)h.h;
  assert( p != NULL );
  return p;
}

void* _cmMidiFileMalloc( _cmMidiFile_t* mfp, unsigned byteN )
{ return cmLHeapAllocZ(mfp->lhH,byteN); }


cmMfRC_t _cmMidiFileRead8( _cmMidiFile_t* mfp, cmMidiByte_t* p )
{
  if( cmFileReadUChar(mfp->fh,p,1) != kOkFileRC )  
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);
  return kOkMfRC;
}

cmMfRC_t _cmMidiFileRead16( _cmMidiFile_t* mfp, unsigned short* p )
{
  if( cmFileReadUShort(mfp->fh,p,1) != kOkFileRC )
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);

  *p = mfSwap16(*p);

  return kOkMfRC;
}

cmMfRC_t _cmMidiFileRead24( _cmMidiFile_t* mfp, unsigned* p )
{
  *p = 0;
  int i = 0;
  for(; i<3; ++i)
  {
    unsigned char c;
    if( cmFileReadUChar(mfp->fh,&c,1) != kOkFileRC )  
      return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);
    *p = (*p << 8) + c;
  }

  //*p =mfSwap32(*p);

  return kOkMfRC;
}

cmMfRC_t _cmMidiFileRead32( _cmMidiFile_t* mfp, unsigned* p )
{
  if( cmFileReadUInt(mfp->fh,p,1) != kOkFileRC )  
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);

  *p = mfSwap32(*p);

  return kOkMfRC;
}

cmMfRC_t _cmMidiFileReadText( _cmMidiFile_t* mfp, cmMidiTrackMsg_t* tmp, unsigned byteN )
{
  if( byteN == 0 )
    return kOkMfRC;

  char*  t = (char*)_cmMidiFileMalloc(mfp,byteN+1);
  t[byteN] = 0;
  
  if( cmFileReadChar(mfp->fh,t,byteN) != kOkFileRC )  
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);

  tmp->u.text  = t;
  tmp->byteCnt = byteN;
  return kOkMfRC;
}

cmMfRC_t _cmMidiFileReadRecd( _cmMidiFile_t* mfp, cmMidiTrackMsg_t* tmp, unsigned byteN )
{
  char*  t = (char*)_cmMidiFileMalloc(mfp,byteN);
  
  if( cmFileReadChar(mfp->fh,t,byteN) != kOkFileRC )  
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);

  tmp->byteCnt = byteN;
  tmp->u.voidPtr = t;

  return kOkMfRC;
}

cmMfRC_t _cmMidiFileReadVarLen( _cmMidiFile_t* mfp, unsigned* p )
{
  unsigned char c;

  if( cmFileReadUChar(mfp->fh,&c,1) != kOkFileRC )  
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);
  
  if( !(c & 0x80) )
    *p = c;
  else
  {
    *p = c & 0x7f;

    do 
    {

      if( cmFileReadUChar(mfp->fh,&c,1) != kOkFileRC )  
        return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);

      *p = (*p << 7) + (c & 0x7f);
    
    }while( c & 0x80 );
  }

  return kOkMfRC; 
}

cmMfRC_t _cmMidiFileAppendTrackMsg( _cmMidiFile_t* mfp, unsigned short trkIdx, unsigned dtick, cmMidiByte_t status, cmMidiTrackMsg_t** trkMsgPtrPtr )
{
  cmMidiTrackMsg_t* tmp = (cmMidiTrackMsg_t*)_cmMidiFileMalloc(mfp, sizeof(cmMidiTrackMsg_t) );
  
  // link new record onto track record chain
  if( mfp->trkV[trkIdx].base == NULL )
    mfp->trkV[trkIdx].base = tmp;
  else
    mfp->trkV[trkIdx].last->link = tmp;

  mfp->trkV[trkIdx].last = tmp;
  mfp->trkV[trkIdx].cnt++;


  // set the generic track record fields
  tmp->dtick     = dtick;
  tmp->status   = status;
  tmp->metaId   = kInvalidMetaMdId;
  tmp->trkIdx   = trkIdx;
  tmp->byteCnt  = 0;
  *trkMsgPtrPtr = tmp;

  return kOkMfRC;
}

cmMfRC_t _cmMidiFileReadSysEx( _cmMidiFile_t* mfp, cmMidiTrackMsg_t* tmp, unsigned byteN )
{
  cmMfRC_t     rc = kOkMfRC;
  cmMidiByte_t b  = 0;

  if( byteN == cmInvalidCnt )
  {

    long offs;
    if( cmFileTell(mfp->fh,&offs) != kOkFileRC )
      return _cmMidiFileError(&mfp->err,kSysFtellFailMfRC);

    byteN = 0;

    // get the length of the sys-ex msg
    while( !cmFileEof(mfp->fh) && (b != kSysComEoxMdId) )
    {
      if((rc = _cmMidiFileRead8(mfp,&b)) != kOkMfRC )
        return rc;
   
      ++byteN;
    }

    // verify that the EOX byte was found
    if( b != kSysComEoxMdId )
      return _cmMidiFileError(&mfp->err,kMissingEoxMfRC);

    // rewind to the beginning of the msg
    if( cmFileSeek(mfp->fh,kBeginFileFl,offs) != kOkFileRC )
      return _cmMidiFileError(&mfp->err,kSysFseekFailMfRC);

  }

  // allocate memory to hold the sys-ex msg
  cmMidiByte_t* mp = (cmMidiByte_t *)_cmMidiFileMalloc(mfp,  byteN );

  // read the sys-ex msg from the file into msg memory
  if( cmFileReadUChar(mfp->fh,mp,byteN) != kOkFileRC )  
    return _cmMidiFileError(&mfp->err,kSysFreadFailMfRC);
  
  tmp->byteCnt     = byteN;
  tmp->u.sysExPtr = mp;
  
  return rc;
}

cmMfRC_t _cmMidiFileReadChannelMsg( _cmMidiFile_t* mfp, cmMidiByte_t* rsPtr, cmMidiByte_t status, cmMidiTrackMsg_t* tmp )
{
  cmMfRC_t       rc       = kOkMfRC;
  cmMidiChMsg_t* p        = (cmMidiChMsg_t*)_cmMidiFileMalloc(mfp,sizeof(cmMidiChMsg_t));
  unsigned     useRsFl  = status <= 0x7f;
  cmMidiByte_t statusCh = useRsFl ? *rsPtr : status;
  
  if( useRsFl )
    p->d0  = status;    
  else
    *rsPtr = status;

  tmp->byteCnt = sizeof(cmMidiChMsg_t);
  tmp->status  = statusCh & 0xf0;
  p->ch        = statusCh & 0x0f;
  p->durTicks  = 0;

  unsigned byteN = cmMidiStatusToByteCount(tmp->status);
  
  if( byteN==kInvalidMidiByte || byteN > 2 )
    return cmErrMsg(&mfp->err,kInvalidStatusMfRC,"Invalid status:0x%x %i.",tmp->status,tmp->status);

  unsigned i;
  for(i=useRsFl; i<byteN; ++i)
  {
    cmMidiByte_t* b = i==0 ? &p->d0 : &p->d1;
  
    if((rc = _cmMidiFileRead8(mfp,b)) != kOkMfRC )
      return rc;
  }

  tmp->u.chMsgPtr = p;
  
  return rc;
}

cmMfRC_t _cmMidiFileReadMetaMsg( _cmMidiFile_t* mfp, cmMidiTrackMsg_t* tmp )
{
  cmMidiByte_t metaId;
  cmMfRC_t     rc;
  unsigned   byteN = 0;

  if((rc = _cmMidiFileRead8(mfp,&metaId)) != kOkMfRC )
    return rc;

  if((rc = _cmMidiFileReadVarLen(mfp,&byteN)) != kOkMfRC )
    return rc;

  //printf("mt: %i 0x%x n:%i\n",metaId,metaId,byteN);

  switch( metaId )
  {
    case kSeqNumbMdId:   rc = _cmMidiFileRead16(mfp,&tmp->u.sVal); break;
    case kTextMdId:      rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kCopyMdId:      rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kTrkNameMdId:   rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kInstrNameMdId: rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kLyricsMdId:    rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kMarkerMdId:    rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kCuePointMdId:  rc = _cmMidiFileReadText(mfp,tmp,byteN);  break;
    case kMidiChMdId:    rc = _cmMidiFileRead8(mfp,&tmp->u.bVal);  break;
    case kEndOfTrkMdId:  break;
    case kTempoMdId:     rc = _cmMidiFileRead24(mfp,&tmp->u.iVal); break;
    case kSmpteMdId:     rc = _cmMidiFileReadRecd(mfp,tmp,sizeof(cmMidiSmpte_t));   break;
    case kTimeSigMdId:   rc = _cmMidiFileReadRecd(mfp,tmp,sizeof(cmMidiTimeSig_t)); break;
    case kKeySigMdId:    rc = _cmMidiFileReadRecd(mfp,tmp,sizeof(cmMidiKeySig_t));  break;
    case kSeqSpecMdId:   rc = _cmMidiFileReadSysEx(mfp,tmp,byteN); break;

    default:
      cmFileSeek(mfp->fh,kCurFileFl,byteN);
      cmErrMsg(&mfp->err,kUnknownMetaIdMfRC,"Unknown meta status:0x%x %i.",metaId,metaId);
      rc = _cmMidiFileError(&mfp->err,kUnknownMetaIdMfRC);
  }

  tmp->metaId = metaId;

  return rc;
}


cmMfRC_t _cmMidiFileReadTrack( _cmMidiFile_t* mfp, unsigned short trkIdx )
{
  cmMfRC_t     rc        = kOkMfRC;
  unsigned     dticks    = 0;
  cmMidiByte_t status;
  cmMidiByte_t runstatus = 0;
  bool         contFl    = true;

  while( contFl && (rc==kOkMfRC))
  { 
    cmMidiTrackMsg_t* tmp = NULL;

    // read the tick count
    if((rc = _cmMidiFileReadVarLen(mfp,&dticks)) != kOkMfRC )
      return rc;

    // read the status byte
    if((rc = _cmMidiFileRead8(mfp,&status)) != kOkMfRC )
      return rc;

    //printf("st:%i 0x%x\n",status,status);

    // append a track msg
    if((rc = _cmMidiFileAppendTrackMsg( mfp, trkIdx, dticks, status, &tmp )) != kOkMfRC )
      return rc;

    // switch on status
    switch( status )
    {
      // handle sys-ex msg
      case kSysExMdId:
        rc = _cmMidiFileReadSysEx(mfp,tmp,cmInvalidCnt);
        break;

        // handle meta msg
      case kMetaStId:
        rc = _cmMidiFileReadMetaMsg(mfp,tmp);

        // ignore unknown meta messages
        if( rc == kUnknownMetaIdMfRC )
          rc = kOkMfRC;

        contFl = tmp->metaId != kEndOfTrkMdId;        
        break;

      default:
          // handle channel msg
          rc = _cmMidiFileReadChannelMsg(mfp,&runstatus,status,tmp);

    }
  }
  return rc;
}


cmMfRC_t _cmMidiFileReadHdr( _cmMidiFile_t* mfp )
{
  cmMfRC_t rc;
  unsigned fileId;
  unsigned chunkByteN;

  // read the file id 
  if((rc = _cmMidiFileRead32(mfp,&fileId)) != kOkMfRC )
    return rc;
  
  // verify the file id
  if( fileId != 'MThd' )
    return _cmMidiFileError(&mfp->err,kNotAMidiFileMfRC);

  // read the file chunk byte count
  if((rc = _cmMidiFileRead32(mfp,&chunkByteN)) != kOkMfRC )
    return  rc;

  // read the format id
  if((rc = _cmMidiFileRead16(mfp,&mfp->fmtId)) != kOkMfRC )
    return rc;

  // read the track count
  if((rc = _cmMidiFileRead16(mfp,&mfp->trkN)) != kOkMfRC )
    return rc;

  // read the ticks per quarter note
  if((rc = _cmMidiFileRead16(mfp,&mfp->ticksPerQN)) != kOkMfRC )
    return rc;

  // if the division field was given in smpte
  if( mfp->ticksPerQN & 0x8000 )
  {
    mfp->smpteFmtId = (mfp->ticksPerQN & 0x7f00) >> 8;
    mfp->smpteTicksPerFrame = (mfp->ticksPerQN & 0xFF);
    mfp->ticksPerQN = 0;
  }

  // allocate and zero the track array
  if( mfp->trkN )
    mfp->trkV = _cmMidiFileMalloc( mfp, sizeof(_cmMidiTrack_t)*mfp->trkN);
  
  return rc;
}

int _cmMidiFileSortFunc( const void *p0, const void* p1 )
{  
  //printf("%i %i\n",(*(cmMidiTrackMsg_t**)p0)->dticks,(*(cmMidiTrackMsg_t**)p1)->dticks);

  if( (*(cmMidiTrackMsg_t**)p0)->dtick == (*(cmMidiTrackMsg_t**)p1)->dtick )
    return 0;

  return (*(cmMidiTrackMsg_t**)p0)->dtick < (*(cmMidiTrackMsg_t**)p1)->dtick ? -1 : 1;  
}

cmMfRC_t _cmMidiFileClose( _cmMidiFile_t* mfp )
{
  cmMfRC_t rc = kOkMfRC;

  if( mfp == NULL )
    return rc;

  cmMemPtrFree(&mfp->msgV);

  if( cmFileIsValid( mfp->fh ) )
    if( cmFileClose( &mfp->fh ) != kOkFileRC )
      rc = _cmMidiFileError(&mfp->err,kSysFcloseFailMfRC);
    
  if( cmLHeapIsValid( mfp->lhH ) )
    cmLHeapDestroy(&mfp->lhH);

  cmMemPtrFree(&mfp);

  return rc;
  
}


cmMfRC_t cmMidiFileOpen( const char* fn, cmMidiFileH_t* hPtr, cmCtx_t* ctx )
{
  cmMfRC_t         rc     = kOkMfRC;
  _cmMidiFile_t* mfp    = NULL;
  unsigned short trkIdx = 0;
  cmErr_t        err;

  cmErrSetup(&err,&ctx->rpt,"MIDI File");

  // allocate the midi file object 
  if(( mfp = cmMemAllocZ( _cmMidiFile_t, 1)) == NULL )
    return rc = _cmMidiFileError(&err,kMemAllocFailMfRC);

  cmErrClone(&mfp->err,&err);

  // allocate the linked heap
  if( cmLHeapIsValid( mfp->lhH = cmLHeapCreate( 1024, ctx )) == false )
  {
    rc = _cmMidiFileError(&err,kMemAllocFailMfRC);
    goto errLabel;
  }

  // open the file
  if(cmFileOpen(&mfp->fh,fn,kReadFileFl | kBinaryFileFl,mfp->err.rpt) != kOkFileRC )
  {
    rc = _cmMidiFileError(&mfp->err,kSysFopenFailMfRC);
    goto errLabel;
  }

  // read header and setup track array
  if(( rc = _cmMidiFileReadHdr(mfp)) != kOkMfRC )
    goto errLabel;
  
  while( !cmFileEof(mfp->fh) && trkIdx < mfp->trkN )
  {
    unsigned chkId=0,chkN=0;

    // read the chunk id
    if((rc = _cmMidiFileRead32(mfp,&chkId)) != kOkMfRC )
      goto errLabel;

    // read the chunk size
    if((rc = _cmMidiFileRead32(mfp,&chkN)) != kOkMfRC )
      goto errLabel;

    // if this is not a trk chunk then skip it
    if( chkId != (unsigned)'MTrk')
    {
      //if( fseek( mfp->fp, chkN, SEEK_CUR) != 0 )
      if( cmFileSeek(mfp->fh,kCurFileFl,chkN) != kOkFileRC )
      {
        rc = _cmMidiFileError(&mfp->err,kSysFseekFailMfRC);
        goto errLabel;
      }
    }  
    else
    {
      if((rc = _cmMidiFileReadTrack(mfp,trkIdx)) != kOkMfRC )
        goto errLabel;

      ++trkIdx;
    }
  }

  // get the total trk msg count
  mfp->msgN = 0;
  for(trkIdx=0; trkIdx<mfp->trkN; ++trkIdx)
    mfp->msgN += mfp->trkV[ trkIdx ].cnt;

  // allocate the trk msg index vector: msgV[]
  mfp->msgV = cmMemAllocZ(cmMidiTrackMsg_t*, mfp->msgN);

  // store a pointer to every trk msg in msgV[] 
  // and convert tick to absolute tick
  unsigned i = 0;
  for(trkIdx=0; trkIdx<mfp->trkN; ++trkIdx)
  {
    unsigned        tick = 0;
    cmMidiTrackMsg_t* tmp  = mfp->trkV[ trkIdx ].base;

    while( tmp != NULL )
    {
      assert( i < mfp->msgN);

      tick          += tmp->dtick; // convert delta-ticks to absolute ticks
      tmp->dtick      = tick;
      mfp->msgV[i]   = tmp;
      tmp            = tmp->link;
      ++i;
    }  
  }

  // sort msgV[] in ascending order on dtick
  qsort( mfp->msgV, mfp->msgN, sizeof(cmMidiTrackMsg_t*), _cmMidiFileSortFunc );

  //for(i=0; i<25; ++i)
  //  printf("%i 0x%x 0x%x\n",mfp->msgV[i]->tick,mfp->msgV[i]->status,mfp->msgV[i]->metaId);

  mfp->fn = _cmMidiFileMalloc(mfp,strlen(fn)+1);
  assert( mfp->fn != NULL );
  strcpy(mfp->fn,fn);

  //
  // calculate the total duration of the MIDI file and convert absolute ticks back to delta ticks
  //
  unsigned mi;
  unsigned prvTick       = 0;


  for(mi=0; mi<mfp->msgN; ++mi)
  {
    cmMidiTrackMsg_t* mp = mfp->msgV[mi];

    // convert absolute ticks back to delta ticks
    unsigned dtick = mp->dtick - prvTick; 
    prvTick   = mp->dtick;
    mp->dtick = dtick;
  }

  hPtr->h = mfp;

 errLabel:

    if( cmFileClose(&mfp->fh) != kOkFileRC )
      rc = _cmMidiFileError(&mfp->err,kCloseFailFileRC);

    if( rc != kOkMfRC )
      _cmMidiFileClose(mfp);

    return rc;
}



cmMfRC_t        cmMidiFileClose( cmMidiFileH_t* h )
{
  cmMfRC_t rc;

  if( cmMidiFileIsNull(*h) )
    return kOkMfRC;

  if((rc = _cmMidiFileClose(_cmMidiFileHandleToPtr(*h))) == kOkMfRC )
    return rc;

  h->h = NULL;
  return rc;
}

unsigned    cmMidiFileTrackCount( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return cmInvalidCnt;

  return mfp->trkN;
}

unsigned    cmMidiFileType( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return cmInvalidId;

  return mfp->fmtId;
}

const char*            cmMidiFileName( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;
  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return NULL;
  return mfp->fn;
}

unsigned    cmMidiFileTicksPerQN( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return cmInvalidCnt;

  return mfp->ticksPerQN;
}

cmMidiByte_t  cmMidiFileTicksPerSmpteFrame( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return kInvalidMidiByte;

  if( mfp->ticksPerQN != 0 )
    return 0;
 
 return mfp->smpteTicksPerFrame;
} 

cmMidiByte_t  cmMidiFileSmpteFormatId( cmMidiFileH_t h )
{ 
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return kInvalidMidiByte;

  if( mfp->ticksPerQN != 0 )
    return 0;
 
 return mfp->smpteFmtId;
}
    
unsigned    cmMidiFileTrackMsgCount( cmMidiFileH_t h, unsigned trackIdx )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return cmInvalidCnt;

  return mfp->trkV[trackIdx].cnt;
}


const cmMidiTrackMsg_t* cmMidiFileTrackMsg( cmMidiFileH_t h, unsigned trackIdx )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return NULL;

  return mfp->trkV[trackIdx].base;
}

unsigned              cmMidiFileMsgCount( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return cmInvalidCnt;

  return mfp->msgN;
}

const cmMidiTrackMsg_t** cmMidiFileMsgArray(    cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp;

  if((mfp = _cmMidiFileHandleToPtr(h)) == NULL )
    return NULL;

  // this cast is needed to eliminate an apparently needless 'incompatible type' warning
  return (const cmMidiTrackMsg_t**)mfp->msgV;
}

unsigned  cmMidiFileSeekUsecs( cmMidiFileH_t h, unsigned offsUSecs, unsigned* msgUsecsPtr, unsigned* microsPerTickPtr )
{
  _cmMidiFile_t* p;

  if((p = _cmMidiFileHandleToPtr(h)) == NULL )
    return cmInvalidIdx;

  if( p->msgN == 0 )
    return cmInvalidIdx;

  unsigned mi;
  unsigned microsPerQN   = 60000000/120;
  unsigned microsPerTick = microsPerQN / p->ticksPerQN;
  unsigned accUSecs      = 0;

  for(mi=0; mi<p->msgN; ++mi)
  {
    const cmMidiTrackMsg_t* mp = p->msgV[mi];

    if( mp->status == kMetaStId && mp->metaId == kTempoMdId )
      microsPerTick = mp->u.iVal / p->ticksPerQN;

    accUSecs += mp->dtick * microsPerTick ;

    if( accUSecs >= offsUSecs )
      break;

  }
  
  if( mi == p->msgN )
    return cmInvalidIdx;

  if( msgUsecsPtr != NULL )
    *msgUsecsPtr = accUSecs - offsUSecs;

  if( microsPerTickPtr != NULL )
    *microsPerTickPtr = microsPerTick;

  return mi;
}

double  cmMidiFileDurSecs( cmMidiFileH_t h )
{
  _cmMidiFile_t* mfp           = _cmMidiFileHandleToPtr(h);
  unsigned       mi;
  double         durSecs       = 0;
  unsigned       microsPerQN   = 60000000/120;
  unsigned       microsPerTick = microsPerQN / mfp->ticksPerQN;

  for(mi=0; mi<mfp->msgN; ++mi)
  {
    cmMidiTrackMsg_t* mp = mfp->msgV[mi];

    if( mp->status == kMetaStId && mp->metaId == kTempoMdId )
      microsPerTick = mp->u.iVal / mfp->ticksPerQN;

    // update the accumulated seconds
    durSecs += (mp->dtick * microsPerTick) / 1000000.0;

  }

  return durSecs;
}

void cmMidiFileTickToMicros( cmMidiFileH_t h )
{
  _cmMidiFile_t* p;

  if((p = _cmMidiFileHandleToPtr(h)) == NULL )
    return;

  if( p->msgN == 0 )
    return;

  unsigned mi;
  unsigned microsPerQN   = 60000000/120; // default tempo
  unsigned microsPerTick = microsPerQN / p->ticksPerQN;

  for(mi=0; mi<p->msgN; ++mi)
  {
    cmMidiTrackMsg_t* mp = p->msgV[mi];

    if( mp->status == kMetaStId && mp->metaId == kTempoMdId )
      microsPerTick = mp->u.iVal / p->ticksPerQN;

    mp->dtick *= microsPerTick;
  }
  
}

typedef struct _cmMidiVoice_str
{
  const  cmMidiTrackMsg_t*  mp;
  unsigned                  durTicks;
  bool                      sustainFl;
  struct _cmMidiVoice_str*  link;
} _cmMidiVoice_t;

void _cmMidFileCalcNoteDurationReleaseNote( _cmMidiVoice_t** listPtrPtr, _cmMidiVoice_t* pp, _cmMidiVoice_t* vp )
{
  // store the duration of the note into the track msg 
  // assoc'd with the note-on msg
  cmMidiChMsg_t* cmp = (cmMidiChMsg_t*)vp->mp->u.chMsgPtr; // cast away const
  cmp->durTicks = vp->durTicks;

  // unlink the active voice msg
  if( pp == NULL )
    *listPtrPtr = vp->link;
  else
    pp->link = vp->link;
  
  // release the voice msg
  cmMemFree(vp);
  
}

void cmMidiFileCalcNoteDurations( cmMidiFileH_t h )
{
  _cmMidiFile_t* p;

  if((p = _cmMidiFileHandleToPtr(h)) == NULL )
    return;

  if( p->msgN == 0 )
    return;

  unsigned        mi;
  _cmMidiVoice_t* list          = NULL;
  _cmMidiVoice_t* vp;
  bool            sustainFlagV[ kMidiChCnt ];

  for(mi=0; mi<p->msgN; ++mi)
  {
    cmMidiTrackMsg_t* mp = p->msgV[mi];

    // update the duration of the sounding notes
    for(vp = list; vp!=NULL; vp=vp->link)
      vp->durTicks += mp->dtick;

    //
    // If this is sustain pedal msg
    //
    if( mp->status==kCtlMdId && mp->u.chMsgPtr->d0 == kSustainCtlMdId )
    {
      assert( mp->u.chMsgPtr->ch < kMidiChCnt );

      // set the state of the sustain pedal flags
      sustainFlagV[mp->u.chMsgPtr->ch] = mp->u.chMsgPtr->d1 >= 64;

      // if the pedal went up ...
      if( sustainFlagV[mp->u.chMsgPtr->ch] == false )
      {
        // ... then release sustaining notes
        _cmMidiVoice_t* pp = NULL;
        for(vp=list; vp != NULL; )
        {
          _cmMidiVoice_t* np = vp->link;
          if( vp->sustainFl && (vp->mp->u.chMsgPtr->ch == mp->u.chMsgPtr->ch) )
            _cmMidFileCalcNoteDurationReleaseNote(&list,pp,vp);
          else
            pp = vp;

          vp = np;
        }
      }
    }
    
    //
    // if this is a note-on msg
    //
    if( mp->status==kNoteOnMdId && mp->u.chMsgPtr->d1>0 )
    {
      vp = cmMemAllocZ(_cmMidiVoice_t,1);
      vp->mp        = mp;
      vp->sustainFl = false;
      vp->link      = list;
      list          = vp;
    }
    else
      //
      // if this is a note-off msg
      //
      if( (mp->status==kNoteOnMdId && mp->u.chMsgPtr->d1==0) || (mp->status==kNoteOffMdId) )
      {
        _cmMidiVoice_t* pp = NULL;

        // for each active voice
        for(vp=list; vp!=NULL; vp=vp->link )
        {
          // if this active voice ch/pitch matches the note-off msg ch pitch 
          if( (vp->mp->u.chMsgPtr->d0==mp->u.chMsgPtr->d0) && (vp->mp->u.chMsgPtr->ch==mp->u.chMsgPtr->ch) )
          {
            if( sustainFlagV[mp->u.chMsgPtr->ch] )
              vp->sustainFl = true;
            else
              _cmMidFileCalcNoteDurationReleaseNote(&list,pp,vp);
            break;
          }

          pp = vp;
        } // end while
      } // end if

  } // end-for
 

  // check for hung notes
  _cmMidiVoice_t* np = NULL;
  vp = list;
  while( vp != NULL )
  {
    np = vp->link;    
    cmErrMsg(&p->err,kMissingNoteOffMfRC,"Missing note-off for note-on:%s",cmMidiToSciPitch(vp->mp->u.chMsgPtr->d0,NULL,0));
    cmMemFree(vp);
    vp = np;
  }
}


void cmMidiFileSetDelay( cmMidiFileH_t h, unsigned ticks )
{
  _cmMidiFile_t* p;
  unsigned mi;

  if((p = _cmMidiFileHandleToPtr(h)) == NULL )
    return;

  if( p->msgN == 0 )
    return;

  for(mi=0; mi<p->msgN; ++mi)
  {
    cmMidiTrackMsg_t* mp = p->msgV[mi];
    
    // locate the first msg which has a non-zero delta tick
    if( mp->dtick > 0 )
    {
      mp->dtick = ticks;
      break;
    }
  }
}

unsigned              cmMidiFilePackTrackMsgBufByteCount( const cmMidiTrackMsg_t* m )
{ return sizeof(cmMidiTrackMsg_t) + m->byteCnt;  }

cmMidiTrackMsg_t*     cmMidiFilePackTrackMsg( const cmMidiTrackMsg_t* m, void* buf, unsigned bufByteCnt )
{
  unsigned          n   = sizeof(cmMidiTrackMsg_t) + m->byteCnt;

  if( n < bufByteCnt )
  {
    assert(0);
    return NULL;
  }

  // copy the cmMidiTrackMsg_t into the buffer
  memcpy(buf, m, sizeof(cmMidiTrackMsg_t));

  if( m->byteCnt > 0 )
  {
    // copy any linked data into the buffer    
    memcpy(buf + sizeof(cmMidiTrackMsg_t), m->u.voidPtr, m->byteCnt );
  
    // fixup the linked data ptr  
    cmMidiTrackMsg_t* mp = (cmMidiTrackMsg_t*)buf;
    mp->u.voidPtr = buf + sizeof(cmMidiTrackMsg_t);
  }
  return (cmMidiTrackMsg_t*)buf;
}



void cmMidiFilePrint( cmMidiFileH_t h, unsigned trkIdx, cmRpt_t* rpt )
{
  const _cmMidiFile_t* mfp = _cmMidiFileHandleToPtr(h);

  if( mfp->fn != NULL )
    cmRptPrintf(rpt,"%s ",mfp->fn);

  cmRptPrintf(rpt,"fmt:%i ticksPerQN:%i tracks:%i\n",mfp->fmtId,mfp->ticksPerQN,mfp->trkN);

  int i = trkIdx == cmInvalidIdx ? 0         : trkIdx;
  int n = trkIdx == cmInvalidIdx ? mfp->trkN : trkIdx+1;

  for(; i<n; ++i)
  {
    cmRptPrintf(rpt,"Track:%i\n",i);
    
    cmMidiTrackMsg_t* tmp = mfp->trkV[i].base;
    while( tmp != NULL )
    {
      cmRptPrintf(rpt,"%5i ", tmp->dtick );

      if( tmp->status == kMetaStId )
        cmRptPrintf(rpt,"%s ", cmMidiMetaStatusToLabel(tmp->metaId)); 
      else
      {
        cmRptPrintf(rpt,"%4s %3i %3i %3i", cmMidiStatusToLabel(tmp->status),tmp->u.chMsgPtr->ch,tmp->u.chMsgPtr->d0,tmp->u.chMsgPtr->d1);
        
      }

      cmRptPrintf(rpt,"\n");
      tmp = tmp->link;
    }
  }  
}

bool cmMidiFileIsNull( cmMidiFileH_t h )
{ return (_cmMidiFile_t*)h.h == NULL; }


void cmMidiFileTestPrint( void* printDataPtr, const char* fmt, va_list vl )
{ vprintf(fmt,vl); }

void cmMidiFileTest( const char* fn, cmCtx_t* ctx )
{
  cmMfRC_t      rc;
  cmMidiFileH_t h;

  if((rc = cmMidiFileOpen(fn,&h,ctx)) != kOkMfRC )
  {
    printf("Error:%i Unable to open the cmMidi file: %s\n",rc,fn);
    return;
  }

  cmMidiFilePrint(h,cmMidiFileTrackCount(h)-1,&ctx->rpt);
  
  printf("Tracks:%i\n",cmMidiFileTrackCount(h));

  cmMidiFileClose(&h);
}