implemented volume control, and restructured slightly

[dos_auplay] / src / audrv.h

#ifndef AUDIO_DRIVER_H_
#define AUDIO_DRIVER_H_

struct audrv {
        void (*start)(int rate, int bits, int nchan);
        void (*pause)(void);
        void (*cont)(void);
        void (*stop)(void);
        void (*setvolume)(int ctl, int vol);
        int (*getvolume)(int ctl);
        int (*isplaying)(void);
};

#endif  /* AUDIO_DRIVER_H_ */