volume: introduce pa_cvolume_{get|set}_position()

src/pulse/volume.c

@@ -685,3 +685,49 @@ pa_cvolume* pa_cvolume_set_fade(pa_cvolume *v, const pa_channel_map *map, float
 
     return v;
 }
+
+pa_cvolume* pa_cvolume_set_position(
+        pa_cvolume *cv,
+        const pa_channel_map *map,
+        pa_channel_position_t t,
+        pa_volume_t v) {
+
+    unsigned c;
+    pa_bool_t good = FALSE;
+
+    pa_assert(cv);
+    pa_assert(map);
+
+    pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(cv, map), NULL);
+    pa_return_val_if_fail(t < PA_CHANNEL_POSITION_MAX, NULL);
+
+    for (c = 0; c < map->channels; c++)
+        if (map->map[c] == t) {
+            cv->values[c] = v;
+            good = TRUE;
+        }
+
+    return good ? cv : NULL;
+}
+
+pa_volume_t pa_cvolume_get_position(
+        pa_cvolume *cv,
+        const pa_channel_map *map,
+        pa_channel_position_t t) {
+
+    unsigned c;
+    pa_volume_t v = PA_VOLUME_MUTED;
+
+    pa_assert(cv);
+    pa_assert(map);
+
+    pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(cv, map), PA_VOLUME_MUTED);
+    pa_return_val_if_fail(t < PA_CHANNEL_POSITION_MAX, PA_VOLUME_MUTED);
+
+    for (c = 0; c < map->channels; c++)
+        if (map->map[c] == t)
+            if (cv->values[c] > v)
+                v = cv->values[c];
+
+    return v;
+}

src/pulse/volume.h

@@ -283,6 +283,19 @@ pa_cvolume* pa_cvolume_set_fade(pa_cvolume *v, const pa_channel_map *map, float
  * volumes are kept. \since 0.9.15 */
 pa_cvolume* pa_cvolume_scale(pa_cvolume *v, pa_volume_t max);
 
+/** Set the passed volume to all channels at the specified channel
+ * position. Will return the updated volume struct, or NULL if there
+ * is no channel at the position specified. You can check if a channel
+ * map includes a specific position by calling
+ * pa_channel_map_has_position(). \since 0.9.16 */
+pa_cvolume* pa_cvolume_set_position(pa_cvolume *cv, const pa_channel_map *map, pa_channel_position_t t, pa_volume_t v);
+
+/** Get the maximum volume of all channels at the specified channel
+ * position. Will return 0 if there is no channel at the position
+ * specified. You can check if a channel map includes a specific
+ * position by calling pa_channel_map_has_position(). \since 0.9.16 */
+pa_volume_t pa_cvolume_get_position(pa_cvolume *cv, const pa_channel_map *map, pa_channel_position_t t);
+
 PA_C_DECL_END
 
 #endif