midi.c

来自「An interactive water fountain. A realis」· C语言 代码 · 共 2,070 行 · 第 1/4 页

        _MIDI_Context = context;
    }
}


/*---------------------------------------------------------------------
   Function: MIDI_GetContext

   Returns the current song context.
---------------------------------------------------------------------*/

int32_t MIDI_GetContext
(
    void
)

{
    return _MIDI_Context;
}


/*---------------------------------------------------------------------
   Function: MIDI_SetLoopFlag

   Sets whether the song should loop when finished or not.
---------------------------------------------------------------------*/

void MIDI_SetLoopFlag
(
    int32_t loopflag
)

{
    _MIDI_Loop = loopflag;
}


/*---------------------------------------------------------------------
   Function: MIDI_ContinueSong

   Continues playback of a paused song.
---------------------------------------------------------------------*/

void MIDI_ContinueSong
(
    void
)

{
    if (_MIDI_SongLoaded)
    {
        _MIDI_SongActive = TRUE;
        MPU_Unpause();
    }
}


/*---------------------------------------------------------------------
   Function: MIDI_PauseSong

   Pauses playback of the current song.
---------------------------------------------------------------------*/

void MIDI_PauseSong
(
    void
)

{
    if (_MIDI_SongLoaded)
    {
        _MIDI_SongActive = FALSE;
        MIDI_AllNotesOff();
        MPU_Pause();
    }
}


/*---------------------------------------------------------------------
   Function: MIDI_SongPlaying

   Returns whether a song is playing or not.
---------------------------------------------------------------------*/

int32_t MIDI_SongPlaying
(
    void
)

{
    return(_MIDI_SongActive);
}


/*---------------------------------------------------------------------
   Function: MIDI_SetMidiFuncs

   Selects the routines that send the MIDI data to the music device.
---------------------------------------------------------------------*/

void MIDI_SetMidiFuncs
(
    midifuncs *funcs
)

{
    _MIDI_Funcs = funcs;
}


/*---------------------------------------------------------------------
   Function: MIDI_StopSong

   Stops playback of the currently playing song.
---------------------------------------------------------------------*/

void MIDI_StopSong
(
    void
)

{
    if (_MIDI_SongLoaded)
    {
        _MIDI_SongActive = FALSE;
        _MIDI_SongLoaded = FALSE;

        MIDI_Reset();
        _MIDI_ResetTracks();

        if (_MIDI_Funcs->ReleasePatches)
        {
            _MIDI_Funcs->ReleasePatches();
        }

        Bfree(_MIDI_TrackPtr);

        _MIDI_TrackPtr     = NULL;
        _MIDI_NumTracks    = 0;
        _MIDI_TrackMemSize = 0;

        _MIDI_TotalTime     = 0;
        _MIDI_TotalTicks    = 0;
        _MIDI_TotalBeats    = 0;
        _MIDI_TotalMeasures = 0;

        MPU_Reset();
    }
}


/*---------------------------------------------------------------------
   Function: MIDI_PlaySong

   Begins playback of a MIDI song.
---------------------------------------------------------------------*/

int32_t MIDI_PlaySong
(
    char *song,
    int32_t loopflag
)

{
    int32_t    numtracks;
    int32_t    format;
    int32_t   headersize;
    int32_t   tracklength;
    track *CurrentTrack;
    char *ptr;

    if (_MIDI_SongLoaded)
    {
        MIDI_StopSong();
    }

    MPU_Init(MUSIC_SoundDevice);

    _MIDI_Loop = loopflag;

    if (_MIDI_Funcs == NULL)
    {
        return(MIDI_NullMidiModule);
    }

    if (*(uint32_t *)song != MIDI_HEADER_SIGNATURE)
    {
        return(MIDI_InvalidMidiFile);
    }

    song += 4;

    headersize      = _MIDI_ReadNumber(song, 4);
    song += 4;
    format          = _MIDI_ReadNumber(song, 2);
    _MIDI_NumTracks = _MIDI_ReadNumber(song + 2, 2);
    _MIDI_Division  = _MIDI_ReadNumber(song + 4, 2);
    if (_MIDI_Division < 0)
    {
        // If a SMPTE time division is given, just set to 96 so no errors occur
        _MIDI_Division = 96;
    }

    if (format > MAX_FORMAT)
    {
        return(MIDI_UnknownMidiFormat);
    }

    ptr = song + headersize;

    if (_MIDI_NumTracks == 0)
    {
        return(MIDI_NoTracks);
    }

    _MIDI_TrackMemSize = _MIDI_NumTracks  * sizeof(track);
    _MIDI_TrackPtr = Bmalloc(_MIDI_TrackMemSize);
    if (_MIDI_TrackPtr == NULL)
    {
        return(MIDI_NoMemory);
    }

    CurrentTrack = _MIDI_TrackPtr;
    numtracks    = _MIDI_NumTracks;
    while (numtracks--)
    {
        if (*(uint32_t *)ptr != MIDI_TRACK_SIGNATURE)
        {
            Bfree(_MIDI_TrackPtr);

            _MIDI_TrackPtr = NULL;
            _MIDI_TrackMemSize = 0;

            return(MIDI_InvalidTrack);
        }

        tracklength = _MIDI_ReadNumber(ptr + 4, 4);
        ptr += 8;
        CurrentTrack->start = ptr;
        ptr += tracklength;
        CurrentTrack++;
    }

    if (_MIDI_Funcs->GetVolume != NULL)
    {
        _MIDI_TotalVolume = _MIDI_Funcs->GetVolume();
    }

    _MIDI_InitEMIDI();

    if (_MIDI_Funcs->LoadPatch)
    {
        MIDI_LoadTimbres();
    }

    _MIDI_ResetTracks();

    if (!Reset)
    {
        MIDI_Reset();
    }

    Reset = FALSE;

    MIDI_SetDivision(_MIDI_Division);
    //MIDI_SetTempo( 120 );

    _MIDI_SongLoaded = TRUE;
    _MIDI_SongActive = TRUE;

    while (_MPU_BuffersWaiting < 4) _MIDI_ServiceRoutine();
    MPU_BeginPlayback();

    return(MIDI_Ok);
}


/*---------------------------------------------------------------------
   Function: MIDI_SetTempo

   Sets the song tempo.
---------------------------------------------------------------------*/

void MIDI_SetTempo
(
    int32_t tempo
)

{
    int32_t tickspersecond;

    MIDI_Tempo = tempo;
    tickspersecond = ((tempo) * _MIDI_Division) / 60;
    _MIDI_FPSecondsPerTick = (1 << TIME_PRECISION) / tickspersecond;
    MPU_SetTempo(tempo);
}

void MIDI_SetDivision(int32_t division)
{
    MPU_SetDivision(division);
}


/*---------------------------------------------------------------------
   Function: MIDI_GetTempo

   Returns the song tempo.
---------------------------------------------------------------------*/

int32_t MIDI_GetTempo
(
    void
)

{
    return(MIDI_Tempo);
}


/*---------------------------------------------------------------------
   Function: _MIDI_ProcessNextTick

   Sets the position of the song pointer.
---------------------------------------------------------------------*/

static int32_t _MIDI_ProcessNextTick
(
    void
)

{
    int32_t   event;
    int32_t   channel;
    int32_t   command;
    track *Track;
    int32_t   tracknum;
    int32_t   status;
    int32_t   c1 = 0;
    int32_t   c2 = 0;
    int32_t   TimeSet = FALSE;

    Track = _MIDI_TrackPtr;
    tracknum = 0;
    while ((tracknum < _MIDI_NumTracks) && (Track != NULL))
    {
        while ((Track->active) && (Track->delay == 0))
        {
            GET_NEXT_EVENT(Track, event);

            if (GET_MIDI_COMMAND(event) == MIDI_SPECIAL)
            {
                switch (event)
                {
                case MIDI_SYSEX :
                case MIDI_SYSEX_CONTINUE :
                    _MIDI_SysEx(Track);
                    break;

                case MIDI_META_EVENT :
                    _MIDI_MetaEvent(Track);
                    break;
                }

                if (Track->active)
                {
                    Track->delay = _MIDI_ReadDelta(Track);
                }

                continue;
            }

            if (event & MIDI_RUNNING_STATUS)
            {
                Track->RunningStatus = event;
            }
            else
            {
                event = Track->RunningStatus;
                Track->pos--;
            }

            channel = GET_MIDI_CHANNEL(event);
            command = GET_MIDI_COMMAND(event);

            if (_MIDI_CommandLengths[ command ] > 0)
            {
                GET_NEXT_EVENT(Track, c1);
                if (_MIDI_CommandLengths[ command ] > 1)
                {
                    GET_NEXT_EVENT(Track, c2);
                }
            }

            if (_MIDI_RerouteFunctions[ channel ] != NULL)
            {
                status = _MIDI_RerouteFunctions[ channel ](event, c1, c2);

                if (status == MIDI_DONT_PLAY)
                {
                    Track->delay = _MIDI_ReadDelta(Track);
                    continue;
                }
            }

            switch (command)
            {
            case MIDI_NOTE_OFF :
                break;

            case MIDI_NOTE_ON :
                break;

            case MIDI_POLY_AFTER_TCH :
                if (_MIDI_Funcs->PolyAftertouch)
                {
                    _MIDI_Funcs->PolyAftertouch(channel, c1, c2);
                }
                break;

            case MIDI_CONTROL_CHANGE :
                TimeSet = _MIDI_InterpretControllerInfo(Track, TimeSet,
                                                        channel, c1, c2);
                break;

            case MIDI_PROGRAM_CHANGE :
                if ((_MIDI_Funcs->ProgramChange) &&
                        (!Track->EMIDI_ProgramChange))
                {
                    _MIDI_Funcs->ProgramChange(channel, c1);
                }
                break;

            case MIDI_AFTER_TOUCH :
                if (_MIDI_Funcs->ChannelAftertouch)
                {
                    _MIDI_Funcs->ChannelAftertouch(channel, c1);
                }
                break;

            case MIDI_PITCH_BEND :
                if (_MIDI_Funcs->PitchBend)
                {
                    _MIDI_Funcs->PitchBend(channel, c1, c2);
                }
                break;

            default :
                break;
            }

            Track->delay = _MIDI_ReadDelta(Track);
        }

        Track->delay--;
        Track++;
        tracknum++;

        if (_MIDI_ActiveTracks == 0)
        {
            break;
        }
    }

    _MIDI_AdvanceTick();

    return(TimeSet);
}


/*---------------------------------------------------------------------
   Function: MIDI_SetSongTick

   Sets the position of the song pointer.
---------------------------------------------------------------------*/

void MIDI_SetSongTick
(
    uint32_t PositionInTicks
)

{
    if (!_MIDI_SongLoaded)
    {
        return;
    }

    MIDI_PauseSong();

    if (PositionInTicks < _MIDI_PositionInTicks)
    {
        _MIDI_ResetTracks();
        MIDI_Reset();
    }

    while (_MIDI_PositionInTicks < PositionInTicks)
    {
        if (_MIDI_ProcessNextTick())
        {
            break;
        }
        if (_MIDI_ActiveTracks == 0)
        {
            _MIDI_ResetTracks();
            if (!_MIDI_Loop)
            {
                return;
            }
            break;
        }
    }

    MIDI_SetVolume(_MIDI_TotalVolume);
    MIDI_ContinueSong();
}


/*---------------------------------------------------------------------
   Function: MIDI_SetSongTime