playmidi.c

SDL_mixer 是一个基于 SDL 的混音器

	voice[i].velocity=e->b;
	recompute_amp(i);
	apply_envelope_to_amp(i);
	return;
      }
}

static void adjust_panning(int c)
{
  int i=voices;
  while (i--)
    if ((voice[i].channel==c) &&
	(voice[i].status==VOICE_ON || voice[i].status==VOICE_SUSTAINED))
      {
	if (voice[i].clone_type != NOT_CLONE) continue;
	voice[i].panning=channel[c].panning;
	recompute_amp(i);
	apply_envelope_to_amp(i);
      }
}

static void drop_sustain(int c)
{
  int i=voices;
  while (i--)
    if (voice[i].status==VOICE_SUSTAINED && voice[i].channel==c)
      finish_note(i);
}

static void adjust_pitchbend(int c)
{
  int i=voices;
  while (i--)
    if (voice[i].status!=VOICE_FREE && voice[i].channel==c)
      {
	recompute_freq(i);
      }
}

static void adjust_volume(int c)
{
  int i=voices;
  while (i--)
    if (voice[i].channel==c &&
	(voice[i].status==VOICE_ON || voice[i].status==VOICE_SUSTAINED))
      {
	recompute_amp(i);
	apply_envelope_to_amp(i);
      }
}

static void seek_forward(int32 until_time)
{
  reset_voices();
  while (current_event->time < until_time)
    {
      switch(current_event->type)
	{
	  /* All notes stay off. Just handle the parameter changes. */

	case ME_PITCH_SENS:
	  channel[current_event->channel].pitchsens=
	    current_event->a;
	  channel[current_event->channel].pitchfactor=0;
	  break;
	  
	case ME_PITCHWHEEL:
	  channel[current_event->channel].pitchbend=
	    current_event->a + current_event->b * 128;
	  channel[current_event->channel].pitchfactor=0;
	  break;
	  
	case ME_MAINVOLUME:
	  channel[current_event->channel].volume=current_event->a;
	  break;
	  
	case ME_MASTERVOLUME:
	  adjust_master_volume(current_event->a + (current_event->b <<7));
	  break;
	  
	case ME_PAN:
	  channel[current_event->channel].panning=current_event->a;
	  break;
	      
	case ME_EXPRESSION:
	  channel[current_event->channel].expression=current_event->a;
	  break;
	  
	case ME_PROGRAM:
	  /* if (ISDRUMCHANNEL(current_event->channel)) */
	  if (channel[current_event->channel].kit)
	    /* Change drum set */
	    channel[current_event->channel].bank=current_event->a;
	  else
	    channel[current_event->channel].program=current_event->a;
	  break;

	case ME_SUSTAIN:
	  channel[current_event->channel].sustain=current_event->a;
	  break;


	case ME_REVERBERATION:
	  channel[current_event->channel].reverberation=current_event->a;
	  break;

	case ME_CHORUSDEPTH:
	  channel[current_event->channel].chorusdepth=current_event->a;
	  break;

	case ME_HARMONICCONTENT:
	  channel[current_event->channel].harmoniccontent=current_event->a;
	  break;

	case ME_RELEASETIME:
	  channel[current_event->channel].releasetime=current_event->a;
	  break;

	case ME_ATTACKTIME:
	  channel[current_event->channel].attacktime=current_event->a;
	  break;

	case ME_BRIGHTNESS:
	  channel[current_event->channel].brightness=current_event->a;
	  break;

	case ME_TONE_KIT:
	  if (current_event->a==SFX_BANKTYPE)
		{
		    channel[current_event->channel].sfx=SFXBANK;
		    channel[current_event->channel].kit=0;
		}
	  else
		{
		    channel[current_event->channel].sfx=0;
		    channel[current_event->channel].kit=current_event->a;
		}
	  break;


	case ME_RESET_CONTROLLERS:
	  reset_controllers(current_event->channel);
	  break;
	      
	case ME_TONE_BANK:
	  channel[current_event->channel].bank=current_event->a;
	  break;
	  
	case ME_EOT:
	  current_sample=current_event->time;
	  return;
	}
      current_event++;
    }
  /*current_sample=current_event->time;*/
  if (current_event != event_list)
    current_event--;
  current_sample=until_time;
}

static void skip_to(int32 until_time)
{
  if (current_sample > until_time)
    current_sample=0;

  reset_midi();
  buffered_count=0;
  buffer_pointer=common_buffer;
  current_event=event_list;
  
  if (until_time)
    seek_forward(until_time);
  ctl->reset();
}

static int apply_controls(void)
{
  int rc, i, did_skip=0;
  int32 val;
  /* ASCII renditions of CD player pictograms indicate approximate effect */
  do
    switch(rc=ctl->read(&val))
      {
      case RC_QUIT: /* [] */
      case RC_LOAD_FILE:	  
      case RC_NEXT: /* >>| */
      case RC_REALLY_PREVIOUS: /* |<< */
	return rc;
	
      case RC_CHANGE_VOLUME:
	if (val>0 || amplification > -val)
	  amplification += val;
	else 
	  amplification=0;
	if (amplification > MAX_AMPLIFICATION)
	  amplification=MAX_AMPLIFICATION;
	adjust_amplification();
	for (i=0; i<voices; i++)
	  if (voice[i].status != VOICE_FREE)
	    {
	      recompute_amp(i);
	      apply_envelope_to_amp(i);
	    }
	ctl->master_volume(amplification);
	break;

      case RC_PREVIOUS: /* |<< */
	if (current_sample < 2*play_mode->rate)
	  return RC_REALLY_PREVIOUS;
	return RC_RESTART;

      case RC_RESTART: /* |<< */
	skip_to(0);
	did_skip=1;
	break;
	
      case RC_JUMP:
	if (val >= sample_count)
	  return RC_NEXT;
	skip_to(val);
	return rc;
	
      case RC_FORWARD: /* >> */
	if (val+current_sample >= sample_count)
	  return RC_NEXT;
	skip_to(val+current_sample);
	did_skip=1;
	break;
	
      case RC_BACK: /* << */
	if (current_sample > val)
	  skip_to(current_sample-val);
	else
	  skip_to(0); /* We can't seek to end of previous song. */
	did_skip=1;
	break;
      }
  while (rc!= RC_NONE);
 
  /* Advertise the skip so that we stop computing the audio buffer */
  if (did_skip)
    return RC_JUMP; 
  else
    return rc;
}

static void do_compute_data(uint32 count)
{
  int i;
  if (!count) return; /* (gl) */
  memset(buffer_pointer, 0, count * num_ochannels * 4);
  for (i=0; i<voices; i++)
    {
      if(voice[i].status != VOICE_FREE)
	{
	  if (!voice[i].sample_offset && voice[i].echo_delay_count)
	    {
		if ((uint32)voice[i].echo_delay_count >= count) voice[i].echo_delay_count -= count;
		else
		  {
	            mix_voice(buffer_pointer+voice[i].echo_delay_count, i, count-voice[i].echo_delay_count);
		    voice[i].echo_delay_count = 0;
		  }
	    }
	  else mix_voice(buffer_pointer, i, count);
	}
    }
  current_sample += count;
}


/* count=0 means flush remaining buffered data to output device, then
   flush the device itself */
static int compute_data(void *stream, int32 count)
{
  int rc, channels;

  if ( play_mode->encoding & PE_MONO )
    channels = 1;
  else
    channels = num_ochannels;

  if (!count)
    {
      if (buffered_count)
          s32tobuf(stream, common_buffer, channels*buffered_count);
      buffer_pointer=common_buffer;
      buffered_count=0;
      return RC_NONE;
    }

  while ((count+buffered_count) >= AUDIO_BUFFER_SIZE)
    {
      do_compute_data(AUDIO_BUFFER_SIZE-buffered_count);
      count -= AUDIO_BUFFER_SIZE-buffered_count;
      s32tobuf(stream, common_buffer, channels*AUDIO_BUFFER_SIZE);
      buffer_pointer=common_buffer;
      buffered_count=0;
      
      ctl->current_time(current_sample);
      if ((rc=apply_controls())!=RC_NONE)
	return rc;
    }
  if (count>0)
    {
      do_compute_data(count);
      buffered_count += count;
      buffer_pointer += count * channels;
    }
  return RC_NONE;
}

int Timidity_PlaySome(void *stream, int samples)
{
  int rc = RC_NONE;
  int32 end_sample;
  
  if ( ! midi_playing ) {
    return RC_NONE;
  }
  end_sample = current_sample+samples;
  while ( current_sample < end_sample ) {
    /* Handle all events that should happen at this time */
    while (current_event->time <= current_sample) {
      switch(current_event->type) {

        /* Effects affecting a single note */

        case ME_NOTEON:
	  current_event->a += channel[current_event->channel].transpose;
          if (!(current_event->b)) /* Velocity 0? */
            note_off(current_event);
          else
            note_on(current_event);
          break;
  
        case ME_NOTEOFF:
	  current_event->a += channel[current_event->channel].transpose;
          note_off(current_event);
          break;
  
        case ME_KEYPRESSURE:
          adjust_pressure(current_event);
          break;
  
          /* Effects affecting a single channel */
  
        case ME_PITCH_SENS:
          channel[current_event->channel].pitchsens=current_event->a;
          channel[current_event->channel].pitchfactor=0;
          break;
          
        case ME_PITCHWHEEL:
          channel[current_event->channel].pitchbend=
            current_event->a + current_event->b * 128;
          channel[current_event->channel].pitchfactor=0;
          /* Adjust pitch for notes already playing */
          adjust_pitchbend(current_event->channel);
          ctl->pitch_bend(current_event->channel, 
              channel[current_event->channel].pitchbend);
          break;
          
        case ME_MAINVOLUME:
          channel[current_event->channel].volume=current_event->a;
          adjust_volume(current_event->channel);
          ctl->volume(current_event->channel, current_event->a);
          break;

	case ME_MASTERVOLUME:
	  adjust_master_volume(current_event->a + (current_event->b <<7));
	  break;
	      
	case ME_REVERBERATION:
	  channel[current_event->channel].reverberation=current_event->a;
	  break;

	case ME_CHORUSDEPTH:
	  channel[current_event->channel].chorusdepth=current_event->a;
	  break;

        case ME_PAN:
          channel[current_event->channel].panning=current_event->a;
          if (adjust_panning_immediately)
            adjust_panning(current_event->channel);
          ctl->panning(current_event->channel, current_event->a);
          break;
          
        case ME_EXPRESSION:
          channel[current_event->channel].expression=current_event->a;
          adjust_volume(current_event->channel);
          ctl->expression(current_event->channel, current_event->a);
          break;
  
        case ME_PROGRAM:
          /* if (ISDRUMCHANNEL(current_event->channel)) { */
	  if (channel[current_event->channel].kit) {
            /* Change drum set */
            channel[current_event->channel].bank=current_event->a;
          }
          else
          {
            channel[current_event->channel].program=current_event->a;
          }
          ctl->program(current_event->channel, current_event->a);
          break;
  
        case ME_SUSTAIN:
          channel[current_event->channel].sustain=current_event->a;
          if (!current_event->a)
            drop_sustain(current_event->channel);
          ctl->sustain(current_event->channel, current_event->a);
          break;
          
        case ME_RESET_CONTROLLERS:
          reset_controllers(current_event->channel);
          redraw_controllers(current_event->channel);
          break;
  
        case ME_ALL_NOTES_OFF:
          all_notes_off(current_event->channel);
          break;
          
        case ME_ALL_SOUNDS_OFF:
          all_sounds_off(current_event->channel);
          break;

	case ME_HARMONICCONTENT:
	  channel[current_event->channel].harmoniccontent=current_event->a;
	  break;

	case ME_RELEASETIME:
	  channel[current_event->channel].releasetime=current_event->a;
	  break;

	case ME_ATTACKTIME:
	  channel[current_event->channel].attacktime=current_event->a;
	  break;

	case ME_BRIGHTNESS:
	  channel[current_event->channel].brightness=current_event->a;
	  break;

        case ME_TONE_BANK:
          channel[current_event->channel].bank=current_event->a;
          break;


	case ME_TONE_KIT:
	  if (current_event->a==SFX_BANKTYPE)
	  {
	    channel[current_event->channel].sfx=SFXBANK;
	    channel[current_event->channel].kit=0;
	  }
	  else
	  {
	    channel[current_event->channel].sfx=0;
	    channel[current_event->channel].kit=current_event->a;
	  }
	  break;

        case ME_EOT:
          /* Give the last notes a couple of seconds to decay  */
          ctl->cmsg(CMSG_INFO, VERB_VERBOSE,
            "Playing time: ~%d seconds", current_sample/play_mode->rate+2);
          ctl->cmsg(CMSG_INFO, VERB_VERBOSE,
            "Notes cut: %d", cut_notes);
          ctl->cmsg(CMSG_INFO, VERB_VERBOSE,
          "Notes lost totally: %d", lost_notes);
          midi_playing = 0;
          return RC_TUNE_END;
        }
      current_event++;
    }
    if (current_event->time > end_sample)
      rc=compute_data(stream, end_sample-current_sample);
    else
      rc=compute_data(stream, current_event->time-current_sample);
    ctl->refresh();
    if ( (rc!=RC_NONE) && (rc!=RC_JUMP))
      break;
  }
  return rc;
}


void Timidity_SetVolume(int volume)
{
  int i;
  if (volume > MAX_AMPLIFICATION)
    amplification=MAX_AMPLIFICATION;
  else
  if (volume < 0)
    amplification=0;
  else
    amplification=volume;
  adjust_amplification();
  for (i=0; i<voices; i++)
    if (voice[i].status != VOICE_FREE)
      {
        recompute_amp(i);
        apply_envelope_to_amp(i);
      }
  ctl->master_volume(amplification);
}

MidiSong *Timidity_LoadSong(char *midifile)
{
  MidiSong *song;
  int32 events;
  SDL_RWops *rw;

  /* Allocate memory for the song */
  song = (MidiSong *)safe_malloc(sizeof(*song));
  memset(song, 0, sizeof(*song));

  /* Open the file */
  strcpy(midi_name, midifile);

  rw = SDL_RWFromFile(midifile, "rb");
  if ( rw != NULL ) {
    song->events=read_midi_file(rw, &events, &song->samples);
    SDL_RWclose(rw);
  }

  /* Make sure everything is okay */
  if (!song->events) {
    free(song);
    song = NULL;
  }
  return(song);
}

MidiSong *Timidity_LoadSong_RW(SDL_RWops *rw)
{
  MidiSong *song;
  int32 events;

  /* Allocate memory for the song */
  song = (MidiSong *)safe_malloc(sizeof(*song));
  memset(song, 0, sizeof(*song));

  strcpy(midi_name, "SDLrwops source");

  song->events=read_midi_file(rw, &events, &song->samples);

  /* Make sure everything is okay */
  if (!song->events) {
    free(song);
    song = NULL;
  }
  return(song);
}

void Timidity_Start(MidiSong *song)
{
  load_missing_instruments();
  adjust_amplification();
  sample_count = song->samples;
  event_list = song->events;
  lost_notes=cut_notes=0;

  skip_to(0);
  midi_playing = 1;
}

int Timidity_Active(void)
{
	return(midi_playing);
}

void Timidity_Stop(void)
{
  midi_playing = 0;
}

void Timidity_FreeSong(MidiSong *song)
{
  if (free_instruments_afterwards)
    free_instruments();
  
  free(song->events);
  free(song);
}

void Timidity_Close(void)
{
  if (resample_buffer) {
    free(resample_buffer);
    resample_buffer=NULL;
  }
  if (common_buffer) {
    free(common_buffer);
    common_buffer=NULL;
  }
  free_instruments();
  free_pathlist();
}