track_smf.c

一个很好的c++ midi解码算法,不依赖于任何平台.

/*
 *  track_smf.cc
 *  Copyright (C) 1998-2000 SAKAI Katsuya
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <stdio.h> // #include <iostream.h>
#include <sys/types.h>

#include "config.h"
#include "extern.h"
#include "smf.h"
#include "defines.h"
#include "midievdefs.h"

u_long SMF_Chunk::ReadVarLen()
{
  register int value;
  if((value=Data[Index])&0x80)
    {
      value &= 0x7F;
      do {
	Index++;
	if (Length<=Index) return 0;
	value = (value<<7) + (Data[Index]&0x7F);
      } while(Data[Index]&0x80);
    }
  Index++;

  return value;
}

u_long SMF_Chunk::ReadLen(int len)
{
  register int value;
  value = Data[Index++];
  while(--len)
    value = (value<<8) + Data[Index++];

  return value;
}


void SMF_Track::init()
{
  Port = 0;
  Index = 0;
  Tick = ReadVarLen();
  for(int i=0;i<16;i++)
    LocalLastStatus[i]=0;
}

int SMF_Track::playaEvent()
{
  u_char nextevent;
  u_long len;
  int rtn=0;
  
#ifdef SHOW_EVENT
  cout << dec <<  "Tick:" << Tick << " Track:"  << Number;
#endif
  
  if(!(EVENT&0x80))
    {	
#ifdef SHOW_EVENT
      cout << " (rs)";
#endif
	  nextevent = LocalLastStatus[Port];
    }
  else
    {
      LocalLastStatus[Port] = nextevent = EVENT;
      Index++;
    }
  
# ifdef SHOW_EVENT
  cout << ' ' << hex << (int)nextevent << ' ';
# endif
  
  switch (nextevent&0xf0)
    {
    case MIDI_NOTEOFF: case MIDI_NOTEON:
    case MIDI_KEY_PRESSURE: case MIDI_CTL_CHANGE: case MIDI_PITCH_BEND:
      if (Length<Index+1)
	{
#ifdef SHOW_INFO
	  cout << "data error" << endl;
#endif
	  return -2;
	}
      aSequencer->midiEvent2(Port, nextevent, Data[Index], Data[Index+1]);
#ifdef SHOW_EVENT
      cout << (int)Data[Index] << ' ' << (int)Data[Index+1] << ' ';
#endif
      Index += 2;
      break;
    case MIDI_PGM_CHANGE: case MIDI_CHN_PRESSURE:
      if (Length<Index)
	{
#ifdef SHOW_INFO
	  cout << "data error2" << endl;
#endif
	  return -2;
	}
      aSequencer->midiEvent1(Port, nextevent, Data[Index]);
#ifdef SHOW_EVENT
      cout << (int)Data[Index]  << ' ';
#endif
      Index++;
      break;
    case MIDI_SYSTEM_PREFIX:
      if(nextevent==META_EVENT)
	{
	  u_char MetaType;
	  MetaType = Data[Index++];
	  len = ReadVarLen(); 
#ifdef SHOW_INFO
	      cout << "len=" << len << " ";
#endif
	  if (Length<Index+len)
	    {
#ifdef SHOW_INFO
	      cout << "data error 3: Length=" << Length
		   << ", Index=" << Index << endl;
#endif
	      return -2;
	    }
	  switch(MetaType)
	    {
	    case META_TEMPO:
	      if(len!=3)
		{
#             ifdef SHOW_EVENT
		  cout << "invalid tempo value" << endl;
#             endif
		  ReadLen(len);
		}
	      else
		{ 
		  // *Tempo = ReadLen(3);
		  aSequencer->set_tempo (ReadLen (3));
#             ifdef SHOW_EVENT
		  cout << "tempo:" << dec << aSequencer->show_tempo() << hex << ' ';
#             endif
		}
	      break;
	    case META_PORT_CHANGE:
	      if(len!=1)
		{
		  ReadLen(len);
#             ifdef SHOW_EVENT
		  cout << "invalid port change event" << endl;
#             endif
		}
	      else
		{
		  Port = ReadLen(1);
#             ifdef SHOW_EVENT
		  cout << "port : " << (int)Port << ' ';				  
#             endif
		}
	      break;
	    case META_TRACKEND:
	      Tick=~0;
#             ifdef SHOW_EVENT
	      cout << "End of Track" << endl;
#             endif
	      return -1;
	      break;
	      
	    default:
#             ifdef SHOW_EVENT
	      cout << "Meta Event ";
#             endif
	      
	      u_int i;
	      char *metadata = new char [len];
	      for (i=0;i<len;i++)
		metadata[i] = Data[Index++];
	      aSequencer->metaEvent (MetaType, len, metadata);
	      
	      delete [] metadata;
	      // Index += len;
	      break;
	    }
	}
      else       // exclusive message
	{
	  u_char ex[512];
	  int exlen=0;
#ifdef RUNNING_ST
	  aSequencer->clearStatus(Port);
#endif
	  len = ReadVarLen();
	  ex[exlen++] = nextevent;
	  for(u_long i=0;i<len;i++)
	    {
#ifdef SHOW_EVENT
	      cout << (int)Data[Index] << ' ';
#endif
	      ex[exlen++] = Data[Index++];
	    }
	  aSequencer->send_exclusive (Port, ex, exlen);
	}
      break;
    default:
      printf("unknown status\n"); // cout << "unknown status" << endl;
      return -3;
      break;
    }
  
  len = ReadVarLen ();
  Tick += len;
  
# ifdef SHOW_EVENT
  cout << "\tNextTick:" << Tick << endl;
# endif
  if (Length<=Index)
    {
#ifdef SHOW_INFO
      cout << "data error 4" << endl;
#endif
      return -2;
    }
  
  if (len==0L)
    rtn = playaEvent ();
 
  return rtn;
}