// init audio context and allocate memory

    char openal_init              (char usehardware, int memorysize);

    // close audio subsytem and free memory

    void openal_close             (void);

    // check if openal_init has been called

    char openal_ready             (void);

    // load an audio file into memory and map it to abuffer

    int  openal_loadfile          (const char *filename);

    // play, pause, stop a single sound source

    void openal_playsound         (unsigned int index);	

    void openal_pausesound        (unsigned int index);

    void openal_stopsound         (unsigned int index);

    // play a sound and set whether it should loop or not (0/1)

    void openal_playsound_loop    (unsigned int index, char loops);

    // stop a sound and free the associated buffer

    void openal_stopsound_free    (unsigned int index, char freesource);

    void openal_freesound         (unsigned int index);

    // set or unset the looping property for a sound source

    void openal_toggleloop        (unsigned int index);

    // set position and volume of a sound source

    void openal_setposition       (unsigned int index, float x, float y, float z);

    void openal_setvolume         (unsigned int index, float gain);

    // set volume for all sounds (gain interval is [0-1])

    void openal_setglobalvolume   (float gain);

    // mute or unmute all sounds    

    void openal_togglemute        (void);

    // fade effect, 

    void openal_fadeout           (unsigned int index, unsigned short int quantity);

    void openal_fadein            (unsigned int index, unsigned short int quantity);

    void openal_fade              (unsigned int index, unsigned short int quantity, char direction);

#define AL_FADE_IN 1

#define AL_FADE_OUT -1