-typedef struct _snd_oss_mixer_slot snd_mixer_oss_slot_t;
-typedef struct _snd_oss_file snd_mixer_oss_file_t;
-
-typedef int (*snd_mixer_oss_get_volume_t)(snd_mixer_oss_file_t *fmixer, snd_mixer_oss_slot_t *chn, int *left, int *right);
-typedef int (*snd_mixer_oss_put_volume_t)(snd_mixer_oss_file_t *fmixer, snd_mixer_oss_slot_t *chn, int left, int right);
-typedef int (*snd_mixer_oss_get_recsrc_t)(snd_mixer_oss_file_t *fmixer, snd_mixer_oss_slot_t *chn, int *active);
-typedef int (*snd_mixer_oss_put_recsrc_t)(snd_mixer_oss_file_t *fmixer, snd_mixer_oss_slot_t *chn, int active);
-typedef int (*snd_mixer_oss_get_recsrce_t)(snd_mixer_oss_file_t *fmixer, unsigned int *active_index);
-typedef int (*snd_mixer_oss_put_recsrce_t)(snd_mixer_oss_file_t *fmixer, unsigned int active_index);
-