mplayer.c

SDL_mixer 是一个基于 SDL 的混音器

	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 (!pf->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 (pf->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 */
			if (pf->panflag)
				a->panning=pf->panning[mp_channel]=PAN_SURROUND;
			break;
		case SS_HIOFFSET: /* SAy set high order sample offset yxx00h */
			if (!pf->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 (pf->vbtick) break;
			if (inf>64) inf=64;
			a->tmpvolume=inf;
			break;
		case VOL_PANNING:
			if (pf->panflag)
				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 ((!pf->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 (!pf->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();

	pf->bpm=speed;
}

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

static void pt_playeffects(void)
{
	UBYTE dat,c;

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

		a->sliding=0;
		switch (c) {
			case UNI_NOTE:
			case UNI_INSTRUMENT:
				a->sliding=oldsliding;
				UniSkipOpcode(c);
				break;
			case UNI_PTEFFECT0:
				dat=UniGetByte();
				if (!pf->vbtick) {
					if ((!dat)&&(pf->flags&UF_ARPMEM)) dat=a->arpmem;
					a->arpmem=dat;
				}
				if (a->period)
					DoArpeggio(a->arpmem);
				break;
			case UNI_PTEFFECT1:
				dat=UniGetByte();
				if ((!pf->vbtick)&&(dat)) a->slidespeed=(UWORD)dat<<2;
				if (a->period)
					if (pf->vbtick) a->tmpperiod-=a->slidespeed;
				break;
			case UNI_PTEFFECT2:
				dat=UniGetByte();
				if ((!pf->vbtick)&&(dat)) a->slidespeed=(UWORD)dat<<2;
				if (a->period)
					if (pf->vbtick) a->tmpperiod+=a->slidespeed;
				break;
			case UNI_PTEFFECT3:
				dat=UniGetByte();
				if ((!pf->vbtick)&&(dat)) a->portspeed=(UWORD)dat<<2;
				if (a->period) {
					if (!a->fadevol)
						a->kick=(a->kick==KICK_NOTE)?KICK_NOTE:KICK_KEYOFF;
					else
						a->kick=(a->kick==KICK_NOTE)?KICK_ENV:KICK_ABSENT;
					DoToneSlide();
					a->ownper=1;
				}
				break;
			case UNI_PTEFFECT4:
			case UNI_XMEFFECT4:
				dat=UniGetByte();
				if (!pf->vbtick) {
					if (dat&0x0f) a->vibdepth=dat&0xf;
					if (dat&0xf0) a->vibspd=(dat&0xf0)>>2;
				} else
				if (a->period) {
					DoVibrato();
					a->ownper=1;
				}
				break;
			case UNI_PTEFFECT5:
				dat=UniGetByte();
				if (a->period) {
					if (!a->fadevol)
						a->kick=(a->kick==KICK_NOTE)?KICK_NOTE:KICK_KEYOFF;
					else
						a->kick=(a->kick==KICK_NOTE)?KICK_ENV:KICK_ABSENT;
					DoToneSlide();
					a->ownper=1;
				}
				DoVolSlide(dat);
				break;
			case UNI_PTEFFECT6:
				dat=UniGetByte();
				if ((a->period)&&(pf->vbtick)) {
					DoVibrato();
					a->ownper=1;
				}
				DoVolSlide(dat);
				break;
			case UNI_PTEFFECT7:
				dat=UniGetByte();
				if (!pf->vbtick) {
					if (dat&0x0f) a->trmdepth=dat&0xf;
					if (dat&0xf0) a->trmspd=(dat&0xf0)>>2;
				}
				if (a->period) {
					DoTremolo();
					a->ownvol=1;
				}
				break;
			case UNI_PTEFFECT8:
				dat=UniGetByte();
				if (pf->panflag)
					a->panning=pf->panning[mp_channel]=dat;
				break;
			case UNI_PTEFFECT9:
				dat=UniGetByte();
				if (!pf->vbtick) {
					if (dat) a->soffset=(UWORD)dat<<8;
					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 UNI_PTEFFECTA:
				DoVolSlide(UniGetByte());
				break;
			case UNI_PTEFFECTB:
				dat=UniGetByte();
				if ((pf->vbtick)||(pf->patdly2)) break;
				/* Vincent Voois uses a nasty trick in "Universal Bolero" */
				if (dat==pf->sngpos && pf->patbrk==pf->patpos) break;
				if ((!pf->loop)&&(!pf->patbrk)&&((dat<pf->sngpos)||
				   ((pf->sngpos==pf->numpos-1)&&(!pf->patbrk))||
				   ((dat==pf->sngpos)&&(pf->flags&UF_NOWRAP)))) {
					/* if we don't loop, better not to skip the end of the
					   pattern, after all... so:
					pf->patbrk=0; */
					pf->posjmp=3;
				} else {
					/* if we were fading, adjust... */
					if (pf->sngpos==(pf->numpos-1))
						pf->volume=pf->initvolume>128?128:pf->initvolume;
					pf->sngpos=dat;
					pf->posjmp=2;
					pf->patpos=0;
				}
				break;
			case UNI_PTEFFECTC:
				dat=UniGetByte();
				if (pf->vbtick) break;
				if (dat==(UBYTE)-1) a->anote=dat=0; /* note cut */
				else if (dat>64) dat=64;
				a->tmpvolume=dat;
				break;
			case UNI_PTEFFECTD:
				dat=UniGetByte();
				if ((pf->vbtick)||(pf->patdly2)) break;
				if ((pf->positions[pf->sngpos]!=255)&&
				   (dat>pf->pattrows[pf->positions[pf->sngpos]]))
					dat=pf->pattrows[pf->positions[pf->sngpos]];
				pf->patbrk=dat;
				if (!pf->posjmp) {
					/* don't ask me to explain this code - it makes
					   backwards.s3m and children.xm (heretic's version) play
					   correctly, among others. Take that for granted, or write
					   the page of comments yourself... you might need some
					   aspirin - Miod */
					if ((pf->sngpos==pf->numpos-1)&&(dat)&&((pf->loop)||
					               (pf->positions[pf->sngpos]==(pf->numpat-1)
									&& !(pf->flags&UF_NOWRAP)))) {
						pf->sngpos=0;
						pf->posjmp=2;
					} else
						pf->posjmp=3;
				}
				break;
			case UNI_PTEFFECTE:
				DoEEffects(UniGetByte());
				break;
			case UNI_PTEFFECTF:
				dat=UniGetByte();
				if (pf->vbtick||pf->patdly2) break;
				if (pf->extspd&&(dat>=0x20))
					pf->bpm=dat;
				else
				  if (dat) {
					pf->sngspd=(dat>32)?32:dat;
					pf->vbtick=0;
				}
				break;
			case UNI_S3MEFFECTA:
				DoS3MSpeed(UniGetByte());
				break;
			case UNI_S3MEFFECTD:
				DoS3MVolSlide(UniGetByte());
				break;
			case UNI_S3MEFFECTE:
				dat=UniGetByte();
				if (a->period)
					DoS3MSlideDn(dat);
				break;
			case UNI_S3MEFFECTF:
				dat=UniGetByte();
				if (a->period)
					DoS3MSlideUp(dat);
				break;
			case UNI_S3MEFFECTI:
				DoS3MTremor(UniGetByte());
				a->ownvol=1;
				break;
			case UNI_S3MEFFECTQ:
				dat=UniGetByte();
				if (a->period)
					DoS3MRetrig(dat);
				break;
			case UNI_S3MEFFECTR:
				dat=UniGetByte();
				if (!pf->vbtick) {
					if (dat&0x0f) a->trmdepth=dat&0xf;
					if (dat&0xf0) a->trmspd=(dat&0xf0)>>2;
				}
				DoS3MTremolo();
				a->ownvol=1;
				break;
			case UNI_S3MEFFECTT:
				DoS3MTempo(UniGetByte());
				break;
			case UNI_S3MEFFECTU:
				dat=UniGetByte();
				if (!pf->vbtick) {
					if (dat&0x0f) a->vibdepth=dat&0xf;
					if (dat&0xf0) a->vibspd=(dat&0xf0)>>2;
				} else
				if (a->period) {
					DoS3MFineVibrato();
					a->ownper=1;
				}
				break;
			case UNI_KEYOFF:
				a->keyoff|=KEY_OFF;
				if ((!(a->volflg&EF_ON))||(a->volflg&EF_LOOP))
					a->keyoff=KEY_KILL;
				break;
			case UNI_KEYFADE:
				dat=UniGetByte();
				if ((pf->vbtick>=dat)||(pf->vbtick==pf->sngspd-1)) {
					a->keyoff=KEY_KILL;
					if (!(a->volflg&EF_ON))
						a->fadevol=0;
				}
				break;
			case UNI_VOLEFFECTS:
				DoVolEffects(UniGetByte());
				break;
			case UNI_XMEFFECTA:
				DoXMVolSlide(UniGetByte());
				break;
			case UNI_XMEFFECTE1: /* XM fineslide up */