+ /** @brief Open mixer device */
+ void (*open_mixer)(void);
+
+ /** @brief Closer mixer device */
+ void (*close_mixer)(void);
+
+ /** @brief Get volume
+ * @param left Where to put the left-channel value
+ * @param right Where to put the right-channel value
+ *
+ * 0 is silent and 100 is maximum volume.
+ */
+ void (*get_volume)(int *left, int *right);
+
+ /** @brief Set volume
+ * @param left Pointer to left-channel value (updated)
+ * @param right Pointer to right-channel value (updated)
+ *
+ * The values are updated with those actually set by the underlying system
+ * call.
+ *
+ * 0 is silent and 100 is maximum volume.
+ */
+ void (*set_volume)(int *left, int *right);
+
+ /** @brief Set configuration */
+ void (*configure)(void);
+