music.c

SDL_mixer 是一个基于 SDL 的混音器

	}
	music_volume = volume;
	SDL_LockAudio();
	if ( music_playing ) {
		music_internal_volume(music_volume);
	}
	SDL_UnlockAudio();
	return(prev_volume);
}

/* Halt playing of music */
static void music_internal_halt(void)
{
	switch (music_playing->type) {
#ifdef CMD_MUSIC
	    case MUS_CMD:
		MusicCMD_Stop(music_playing->data.cmd);
		break;
#endif
#ifdef WAV_MUSIC
	    case MUS_WAV:
		WAVStream_Stop();
		break;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	    case MUS_MOD:
		Player_Stop();
		break;
#endif
#ifdef MID_MUSIC
	    case MUS_MID:
#ifdef USE_NATIVE_MIDI
		if ( native_midi_ok ) {
			native_midi_stop();
		} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
		if ( timidity_ok ) {
			Timidity_Stop();
		}
#endif
		break;
#endif
#ifdef OGG_MUSIC
	    case MUS_OGG:
		OGG_stop(music_playing->data.ogg);
		break;
#endif
#ifdef MP3_MUSIC
	    case MUS_MP3:
		smpeg.SMPEG_stop(music_playing->data.mp3);
		break;
#endif
	    default:
		/* Unknown music type?? */
		return;
	}
	music_playing->fading = MIX_NO_FADING;
	music_playing = NULL;
}
int Mix_HaltMusic(void)
{
	SDL_LockAudio();
	if ( music_playing ) {
		music_internal_halt();
	}
	SDL_UnlockAudio();

	return(0);
}

/* Progressively stop the music */
int Mix_FadeOutMusic(int ms)
{
	int retval = 0;

	if (ms <= 0) {  /* just halt immediately. */
		Mix_HaltMusic();
		return 1;
	}

	SDL_LockAudio();
	if ( music_playing) {
                int fade_steps = (ms + ms_per_step - 1)/ms_per_step;
                if ( music_playing->fading == MIX_NO_FADING ) {
	        	music_playing->fade_step = 0;
                } else {
                        int step;
                        int old_fade_steps = music_playing->fade_steps;
                        if ( music_playing->fading == MIX_FADING_OUT ) {
                                step = music_playing->fade_step;
                        } else {
                                step = old_fade_steps
                                        - music_playing->fade_step + 1;
                        }
                        music_playing->fade_step = (step * fade_steps)
                                / old_fade_steps;
                }
		music_playing->fading = MIX_FADING_OUT;
		music_playing->fade_steps = fade_steps;
		retval = 1;
	}
	SDL_UnlockAudio();

	return(retval);
}

Mix_Fading Mix_FadingMusic(void)
{
	Mix_Fading fading = MIX_NO_FADING;

	SDL_LockAudio();
	if ( music_playing ) {
		fading = music_playing->fading;
	}
	SDL_UnlockAudio();

	return(fading);
}

/* Pause/Resume the music stream */
void Mix_PauseMusic(void)
{
	music_active = 0;
}

void Mix_ResumeMusic(void)
{
	music_active = 1;
}

void Mix_RewindMusic(void)
{
	Mix_SetMusicPosition(0.0);
}

int Mix_PausedMusic(void)
{
	return (music_active == 0);
}

/* Check the status of the music */
static int music_internal_playing()
{
	int playing = 1;
	switch (music_playing->type) {
#ifdef CMD_MUSIC
	    case MUS_CMD:
		if (!MusicCMD_Active(music_playing->data.cmd)) {
			playing = 0;
		}
		break;
#endif
#ifdef WAV_MUSIC
	    case MUS_WAV:
		if ( ! WAVStream_Active() ) {
			playing = 0;
		}
		break;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	    case MUS_MOD:
		if ( ! Player_Active() ) {
			playing = 0;
		}
		break;
#endif
#ifdef MID_MUSIC
	    case MUS_MID:
#ifdef USE_NATIVE_MIDI
		if ( native_midi_ok ) {
			if ( ! native_midi_active() )
				playing = 0;
		} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
		if ( timidity_ok ) {
			if ( ! Timidity_Active() )
				playing = 0;
		}
#endif
		break;
#endif
#ifdef OGG_MUSIC
	    case MUS_OGG:
		if ( ! OGG_playing(music_playing->data.ogg) ) {
			playing = 0;
		}
		break;
#endif
#ifdef MP3_MUSIC
	    case MUS_MP3:
		if ( smpeg.SMPEG_status(music_playing->data.mp3) != SMPEG_PLAYING )
			playing = 0;
		break;
#endif
	    default:
		playing = 0;
		break;
	}
	return(playing);
}
int Mix_PlayingMusic(void)
{
	int playing = 0;

	SDL_LockAudio();
	if ( music_playing ) {
		playing = music_internal_playing();
	}
	SDL_UnlockAudio();

	return(playing);
}

/* Set the external music playback command */
int Mix_SetMusicCMD(const char *command)
{
	Mix_HaltMusic();
	if ( music_cmd ) {
		free(music_cmd);
		music_cmd = NULL;
	}
	if ( command ) {
		music_cmd = (char *)malloc(strlen(command)+1);
		if ( music_cmd == NULL ) {
			return(-1);
		}
		strcpy(music_cmd, command);
	}
	return(0);
}

#ifdef LIBMIKMOD_MUSIC
static int _pl_synchro_value;
void Player_SetSynchroValue(int i)
{
	fprintf(stderr,"SDL_mixer: Player_SetSynchroValue is not supported.\n");
	_pl_synchro_value = i;
}

int Player_GetSynchroValue(void)
{
	fprintf(stderr,"SDL_mixer: Player_GetSynchroValue is not supported.\n");
	return _pl_synchro_value;
}
#endif

int Mix_SetSynchroValue(int i)
{
	if ( music_playing && ! music_stopped ) {
		switch (music_playing->type) {
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
		    case MUS_MOD:
			if ( ! Player_Active() ) {
				return(-1);
			}
			Player_SetSynchroValue(i);
			return 0;
			break;
#endif
		    default:
			return(-1);
			break;
		}
		return(-1);
	}
	return(-1);
}

int Mix_GetSynchroValue(void)
{
	if ( music_playing && ! music_stopped ) {
		switch (music_playing->type) {
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
		    case MUS_MOD:
			if ( ! Player_Active() ) {
				return(-1);
			}
			return Player_GetSynchroValue();
			break;
#endif
		    default:
			return(-1);
			break;
		}
		return(-1);
	}
	return(-1);
}


/* Uninitialize the music players */
void close_music(void)
{
	Mix_HaltMusic();
#ifdef CMD_MUSIC
	Mix_SetMusicCMD(NULL);
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	MikMod_Exit();
# ifndef LIBMIKMOD_MUSIC
	MikMod_UnregisterAllLoaders();
	MikMod_UnregisterAllDrivers();
# endif
#endif
#ifdef MID_MUSIC
# ifdef USE_TIMIDITY_MIDI
	Timidity_Close();
# endif
#endif
}

# ifdef LIBMIKMOD_MUSIC
typedef struct
{
	MREADER mr;
	int offset;
	int eof;
	SDL_RWops *rw;
} LMM_MREADER;
BOOL LMM_Seek(struct MREADER *mr,long to,int dir)
{
	int at;
	LMM_MREADER* lmmmr=(LMM_MREADER*)mr;
	if(dir==SEEK_SET)
		to+=lmmmr->offset;
	at=SDL_RWseek(lmmmr->rw, to, dir);
	return at<lmmmr->offset;
}
long LMM_Tell(struct MREADER *mr)
{
	int at;
	LMM_MREADER* lmmmr=(LMM_MREADER*)mr;
	at=SDL_RWtell(lmmmr->rw)-lmmmr->offset;
	return at;
}
BOOL LMM_Read(struct MREADER *mr,void *buf,size_t sz)
{
	int got;
	LMM_MREADER* lmmmr=(LMM_MREADER*)mr;
	got=SDL_RWread(lmmmr->rw, buf, sz, 1);
	return got;
}
int LMM_Get(struct MREADER *mr)
{
	unsigned char c;
	int i=EOF;
	LMM_MREADER* lmmmr=(LMM_MREADER*)mr;
	if(SDL_RWread(lmmmr->rw,&c,1,1))
		i=c;
	return i;
}
BOOL LMM_Eof(struct MREADER *mr)
{
	int offset;
	LMM_MREADER* lmmmr=(LMM_MREADER*)mr;
	offset=LMM_Tell(mr);
	return offset>=lmmmr->eof;
}
MODULE *MikMod_LoadSongRW(SDL_RWops *rw, int maxchan)
{
	LMM_MREADER lmmmr={
		LMM_Seek,
		LMM_Tell,
		LMM_Read,
		LMM_Get,
		LMM_Eof,
		0,
		0,
		rw
	};
	MODULE *m;
	lmmmr.offset=SDL_RWtell(rw);
	SDL_RWseek(rw,0,SEEK_END);
	lmmmr.eof=SDL_RWtell(rw);
	SDL_RWseek(rw,lmmmr.offset,SEEK_SET);
	m=Player_LoadGeneric((MREADER*)&lmmmr,maxchan,0);
	return m;
}
# endif

Mix_Music *Mix_LoadMUS_RW(SDL_RWops *rw) {
	Uint8 magic[5];	  /*Apparently there is no way to check if the file is really a MOD,*/
	/*		    or there are too many formats supported by MikMod or MikMod does */
	/*		    this check by itself. If someone implements other formats (e.g. MP3) */
	/*		    the check can be uncommented */
	Mix_Music *music;
	int start;

	/* Figure out what kind of file this is */
	start = SDL_RWtell(rw);
	if (SDL_RWread(rw,magic,1,4)!=4) {
		Mix_SetError("Couldn't read from RWops");
		return NULL;
	}
	SDL_RWseek(rw, start, SEEK_SET);
	magic[4]='\0';

	/* Allocate memory for the music structure */
	music=(Mix_Music *)malloc(sizeof(Mix_Music));
	if (music==NULL ) {
		Mix_SetError("Out of memory");
		return(NULL);
	}
	music->error = 0;

#ifdef OGG_MUSIC
	/* Ogg Vorbis files have the magic four bytes "OggS" */
	if ( strcmp((char *)magic, "OggS") == 0 ) {
		music->type = MUS_OGG;
		music->data.ogg = OGG_new_RW(rw);
		if ( music->data.ogg == NULL ) {
			music->error = 1;
		}
	} else
#endif
#ifdef MP3_MUSIC
	if ( magic[0] == 0xFF && (magic[1] & 0xF0) == 0xF0 ) {
		if ( Mix_InitMP3() == 0 ) {
			SMPEG_Info info;
			music->type = MUS_MP3;
			music->data.mp3 = smpeg.SMPEG_new_rwops(rw, &info, 0);
			if ( !info.has_audio ) {
				Mix_SetError("MPEG file does not have any audio stream.");
				music->error = 1;
			} else {
				smpeg.SMPEG_actualSpec(music->data.mp3, &used_mixer);
			}
		} else {
			music->error = 1;
		}
	} else
#endif
#ifdef MID_MUSIC
	/* MIDI files have the magic four bytes "MThd" */
	if ( strcmp((char *)magic, "MThd") == 0 ) {
		music->type = MUS_MID;
		music->error = 1;
#ifdef USE_NATIVE_MIDI
		if ( native_midi_ok ) {
			music->data.nativemidi = native_midi_loadsong_RW(rw);
			if ( music->data.nativemidi ) {
				music->error = 0;
			}
		} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
		if ( timidity_ok ) {
			music->data.midi = Timidity_LoadSong_RW(rw);
			if ( music->data.midi ) {
				music->error = 0;
			}
		}
#endif
	} else
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	if (1) {
		music->type=MUS_MOD;
		music->data.module=MikMod_LoadSongRW(rw,64);
		if (music->data.module==NULL) {
			Mix_SetError("%s",MikMod_strerror(MikMod_errno));
			music->error=1;
		} else {
			/* Stop implicit looping, fade out and other flags. */
			music->data.module->extspd  = 1;
			music->data.module->panflag = 1;
			music->data.module->wrap    = 0;
			music->data.module->loop    = 0;
#if 0 /* Don't set fade out by default - unfortunately there's no real way
         to query the status of the song or set trigger actions.  Hum. */
			music->data.module->fadeout = 1;
#endif
		}
	} else
#endif
	{
		Mix_SetError("Unrecognized music format");
		music->error=1;
	}
	if (music->error) {
		free(music);
		music=NULL;
	}
	return(music);
}