mod.c

MIDI解码程序(用VC编写)

DoXMGlobalSlide (UBYTE inf)
{
  if (mp.vbtick)
    {
      if (inf)
	mp.globalslide = inf;
      else
	inf = mp.globalslide;
      if (inf & 0xf0)
	inf &= 0xf0;
      mp.volume = mp.volume + ((inf >> 4) - (inf & 0xf)) * 2;

      if (mp.volume < 0)
	mp.volume = 0;
      else if (mp.volume > 128)
	mp.volume = 128;
    }
}

static void 
DoXMPanSlide (UBYTE inf)
{
  UBYTE lo, hi;
  SWORD pan;

  if (inf)
    a->pansspd = inf;
  else
    inf = a->pansspd;

  if (!mp.vbtick)
    return;

  lo = inf & 0xf;
  hi = inf >> 4;

  /* slide right has absolute priority */
  if (hi)
    lo = 0;

  pan = ((a->panning == PAN_SURROUND) ? PAN_CENTER : a->panning) + hi - lo;

  a->panning = (pan < PAN_LEFT) ? PAN_LEFT : (pan > PAN_RIGHT ? PAN_RIGHT : pan);
}

static void 
DoXMExtraFineSlideUp (UBYTE inf)
{
  if (!mp.vbtick)
    {
      a->period -= inf;
      a->tmpperiod -= inf;
    }
}

static void 
DoXMExtraFineSlideDown (UBYTE inf)
{
  if (!mp.vbtick)
    {
      a->period += inf;
      a->tmpperiod += inf;
    }
}

/*========== Impulse Tracker effects */

static void 
DoITChanVolSlide (UBYTE inf)
{
  UBYTE lo, hi;

  if (inf)
    a->chanvolslide = inf;
  inf = a->chanvolslide;

  lo = inf & 0xf;
  hi = inf >> 4;

  if (!hi)
    a->chanvol -= lo;
  else if (!lo)
    {
      a->chanvol += hi;
    }
  else if (hi == 0xf)
    {
      if (!mp.vbtick)
	a->chanvol -= lo;
    }
  else if (lo == 0xf)
    {
      if (!mp.vbtick)
	a->chanvol += hi;
    }

  if (a->chanvol < 0)
    a->chanvol = 0;
  if (a->chanvol > 64)
    a->chanvol = 64;
}

static void 
DoITGlobalSlide (UBYTE inf)
{
  UBYTE lo, hi;

  if (inf)
    mp.globalslide = inf;
  inf = mp.globalslide;

  lo = inf & 0xf;
  hi = inf >> 4;

  if (!lo)
    {
      if (mp.vbtick)
	mp.volume += hi;
    }
  else if (!hi)
    {
      if (mp.vbtick)
	mp.volume -= lo;
    }
  else if (lo == 0xf)
    {
      if (!mp.vbtick)
	mp.volume += hi;
    }
  else if (hi == 0xf)
    {
      if (!mp.vbtick)
	mp.volume -= lo;
    }

  if (mp.volume < 0)
    mp.volume = 0;
  if (mp.volume > 128)
    mp.volume = 128;
}

static void 
DoITPanSlide (UBYTE inf)
{
  UBYTE lo, hi;
  SWORD pan;

  if (inf)
    a->pansspd = inf;
  else
    inf = a->pansspd;

  lo = inf & 0xf;
  hi = inf >> 4;

  pan = (a->panning == PAN_SURROUND) ? PAN_CENTER : a->panning;

  if (!hi)
    pan += lo << 2;
  else if (!lo)
    {
      pan -= hi << 2;
    }
  else if (hi == 0xf)
    {
      if (!mp.vbtick)
	pan += lo << 2;
    }
  else if (lo == 0xf)
    {
      if (!mp.vbtick)
	pan -= hi << 2;
    }
  a->panning =			/*pf->panning[mp.channel]= */
    (pan < PAN_LEFT) ? PAN_LEFT : (pan > PAN_RIGHT ? PAN_RIGHT : pan);
}

static void 
DoITTempo (UBYTE tempo)
{
  SWORD temp = mp.newbpm;

  if (mp.patdly2)
    return;

  if (tempo & 0x10)
    temp += (tempo & 0x0f);
  else
    temp -= tempo;

  mp.newbpm = (temp > 255) ? 255 : (temp < 1 ? 1 : temp);
}

static void 
DoITVibrato (void)
{
  UBYTE q;
  UWORD temp = 0;

  q = (a->vibpos >> 2) & 0x1f;

  switch (a->wavecontrol & 3)
    {
    case 0:			/* sine */
      temp = VibratoTable[q];
      break;
    case 1:			/* square wave */
      temp = 255;
      break;
    case 2:			/* ramp down */
      q <<= 3;
      if (a->vibpos < 0)
	q = 255 - q;
      temp = q;
      break;
    case 3:			/* random */
      temp = getrandom (256);
      break;
    }

  temp *= a->vibdepth;
  temp >>= 8;
  temp <<= 2;

  if (a->vibpos >= 0)
    a->period = a->tmpperiod + temp;
  else
    a->period = a->tmpperiod - temp;

  a->vibpos += a->vibspd;
}

static void 
DoITFineVibrato (void)
{
  UBYTE q;
  UWORD temp = 0;

  q = (a->vibpos >> 2) & 0x1f;

  switch (a->wavecontrol & 3)
    {
    case 0:			/* sine */
      temp = VibratoTable[q];
      break;
    case 1:			/* square wave */
      temp = 255;
      break;
    case 2:			/* ramp down */
      q <<= 3;
      if (a->vibpos < 0)
	q = 255 - q;
      temp = q;
      break;
    case 3:			/* random */
      temp = getrandom (256);
      break;
    }

  temp *= a->vibdepth;
  temp >>= 8;

  if (a->vibpos >= 0)
    a->period = a->tmpperiod + temp;
  else
    a->period = a->tmpperiod - temp;

  a->vibpos += a->vibspd;
}

static void 
DoITTremor (UBYTE inf)
{
  UBYTE on, off;

  if (inf)
    a->s3mtronof = inf;
  else
    {
      inf = a->s3mtronof;
      if (!inf)
	return;
    }

  if (!mp.vbtick)
    return;

  on = (inf >> 4);
  off = (inf & 0xf);

  a->s3mtremor %= (on + off);
  a->volume = (a->s3mtremor < on) ? a->tmpvolume : 0;
  a->s3mtremor++;
}

static void 
DoITPanbrello (void)
{
  UBYTE q;
  SLONG temp = 0;

  q = a->panbpos;

  switch (a->panbwave)
    {
    case 0:			/* sine */
      temp = PanbrelloTable[q];
      break;
    case 1:			/* square wave */
      temp = (q < 0x80) ? 64 : 0;
      break;
    case 2:			/* ramp down */
      q <<= 3;
      temp = q;
      break;
    case 3:			/* random */
      if (a->panbpos >= a->panbspd)
	{
	  a->panbpos = 0;
	  temp = getrandom (256);
	}
    }

  temp *= a->panbdepth;
  temp = (temp / 8) + pf->panning[mp.channel];

  a->panning = (temp < PAN_LEFT) ? PAN_LEFT : (temp > PAN_RIGHT ? PAN_RIGHT : temp);
  a->panbpos += a->panbspd;
}

static void 
DoITToneSlide (void)
{
  /* if we don't come from another note, ignore the slide and play the note
     as is */
  if (!a->oldnote)
    return;

  if (mp.vbtick)
    {
      int dist;

      /* We have to slide a->period towards a->wantedperiod, compute the
         difference between those two values */
      dist = a->period - a->wantedperiod;

      /* if they are equal or if portamentospeed is too big... */
      if ((!dist) || ((a->portspeed << 2) > abs (dist)))
	/* ... make tmpperiod equal tperiod */
	a->tmpperiod = a->period = a->wantedperiod;
      else if (dist > 0)
	{
	  a->tmpperiod -= a->portspeed << 2;
	  a->period -= a->portspeed << 2;	/* dist>0 slide up */
	}
      else
	{
	  a->tmpperiod += a->portspeed << 2;
	  a->period += a->portspeed << 2;	/* dist<0 slide down */
	}
    }
  else
    a->tmpperiod = a->period;
}

static void DoNNAEffects (UBYTE dat);
/* Impulse/Scream Tracker Sxx effects.
   All Sxx effects share the same memory space. */
static void 
DoSSEffects (UBYTE dat)
{
  UBYTE inf, c;

  inf = dat & 0xf;
  c = dat >> 4;

  if (!dat)
    {
      c = a->sseffect;
      inf = a->ssdata;
    }
  else
    {
      a->sseffect = c;
      a->ssdata = inf;
    }

  switch (c)
    {
    case SS_GLISSANDO:		/* S1x set glissando voice */
      DoEEffects (0x30 | inf);
      break;
    case SS_FINETUNE:		/* S2x set finetune */
      DoEEffects (0x50 | inf);
      break;
    case SS_VIBWAVE:		/* S3x set vibrato waveform */
      DoEEffects (0x40 | inf);
      break;
    case SS_TREMWAVE:		/* S4x set tremolo waveform */
      DoEEffects (0x70 | inf);
      break;
    case SS_PANWAVE:		/* S5x panbrello */
      a->panbwave = inf;
      break;
    case SS_FRAMEDELAY:	/* S6x delay x number of frames (patdly) */
      DoEEffects (0xe0 | inf);
      break;
    case SS_S7EFFECTS:		/* S7x instrument / NNA commands */
      DoNNAEffects (inf);
      break;
    case SS_PANNING:		/* S8x set panning position */
      DoEEffects (0x80 | inf);
      break;
    case SS_SURROUND:		/* S9x set surround sound */
      a->panning = pf->panning[mp.channel] = PAN_SURROUND;
      break;
    case SS_HIOFFSET:		/* SAy set high order sample offset yxx00h */
      if (!mp.vbtick)
	{
	  a->hioffset = inf << 16;
	  a->start = a->hioffset | a->soffset;

	  if ((a->s) && (a->start > a->s->length))
	    a->start = a->s->flags & (SF_LOOP | SF_BIDI) ? a->s->loopstart : a->s->length;
	}
      break;
    case SS_PATLOOP:		/* SBx pattern loop */
      DoEEffects (0x60 | inf);
      break;
    case SS_NOTECUT:		/* SCx notecut */
      DoEEffects (0xC0 | inf);
      break;
    case SS_NOTEDELAY:		/* SDx notedelay */
      DoEEffects (0xD0 | inf);
      break;
    case SS_PATDELAY:		/* SEx patterndelay */
      DoEEffects (0xE0 | inf);
      break;
    }
}

/* Impulse Tracker Volume/Pan Column effects.
   All volume/pan column effects share the same memory space. */
static void 
DoVolEffects (UBYTE c)
{
  UBYTE inf = UniGetByte ();

  if ((!c) && (!inf))
    {
      c = a->voleffect;
      inf = a->voldata;
    }
  else
    {
      a->voleffect = c;
      a->voldata = inf;
    }

  if (c)
    switch (c)
      {
      case VOL_VOLUME:
	if (mp.vbtick)
	  break;
	if (inf > 64)
	  inf = 64;
	a->tmpvolume = inf;
	break;
      case VOL_PANNING:
	a->panning = /*pf->panning[mp.channel]= */ inf;
	break;
      case VOL_VOLSLIDE:
	DoS3MVolSlide (inf);
	break;
      case VOL_PITCHSLIDEDN:
	if (a->period)
	  DoS3MSlideDn (inf);
	break;
      case VOL_PITCHSLIDEUP:
	if (a->period)
	  DoS3MSlideUp (inf);
	break;
      case VOL_PORTAMENTO:
	if (inf)
	  a->slidespeed = inf;
	if (a->period)
	  {
	    if ((!mp.vbtick) || (a->newsamp))
	      {
		a->kick = KICK_NOTE;
		a->start = -1;
	      }
	    else
	      a->kick = (a->kick == KICK_NOTE) ? KICK_ENV : KICK_ABSENT;
	    DoITToneSlide ();
	    a->ownper = 1;
	  }
	break;
      case VOL_VIBRATO:
	if (!mp.vbtick)
	  {
	    if (inf & 0x0f)
	      a->vibdepth = inf & 0xf;
	    if (inf & 0xf0)
	      a->vibspd = (inf & 0xf0) >> 2;
	  }
	if (a->period)
	  {
	    DoITVibrato ();
	    a->ownper = 1;
	  }
	break;
      }
}

/*========== UltraTracker effects */

static void 
DoULTSampleOffset (void)
{
  UWORD offset = UniGetWord ();

  if (offset)
    a->ultoffset = offset;

  a->start = a->ultoffset << 2;
  if ((a->s) && (a->start > a->s->length))
    a->start = a->s->flags & (SF_LOOP | SF_BIDI) ? a->s->loopstart : a->s->length;
}

/*========== OctaMED effects */

static void 
DoMEDSpeed (void)
{
  UWORD speed = UniGetWord ();

  mp.newbpm = speed;
}

/*========== General player functions */

static void 
pt_playeffects (void)
{
  UBYTE dat, c, oldc = 0;

  while ((c = UniGetByte ()))
    {
      int oldsliding = a->sliding;

      a->sliding = 0;

      /* libunimod doesn't *quite* do Ultimate Soundtracker portas correctly */
      if (strcmp(of.modtype, "Ultimate Soundtracker") == 0)
        {
      if (c == 5 && oldc == 4)
        {
          oldc = 5;
          a->sliding = oldsliding;
          UniSkipOpcode (c);
          continue;
        }
        oldc = c;
        if (c == 3 || c == 4)
            c++;
      }

      switch (c)
	{
	case UNI_PTEFFECT0:
	  dat = UniGetByte ();
	  if (!mp.vbtick)
	    {
	      if ((!dat) && (pf->flags & UF_ARPMEM))
		dat = a->arpmem;
	      else
	        a->arpmem = dat;
	    }
	  if (a->period)
	    DoArpeggio (a->arpmem);
	  break;
	case UNI_PTEFFECT1:
	  dat = UniGetByte ();
	  if ((!mp.vbtick) && (dat))
	    a->slidespeed = (UWORD) dat << 2;
	  if (a->period)