implement pa_cvolume_scale()

src/map-file

@@ -113,6 +113,7 @@ pa_cvolume_get_balance;
 pa_cvolume_init;
 pa_cvolume_max;
 pa_cvolume_remap;
+pa_cvolume_scale;
 pa_cvolume_set;
 pa_cvolume_set_balance;
 pa_cvolume_snprint;

src/pulse/volume.c

@@ -500,3 +500,22 @@ pa_cvolume* pa_cvolume_set_balance(const pa_channel_map *map, pa_cvolume *v, flo
 
     return v;
 }
+
+pa_cvolume* pa_cvolume_scale(pa_cvolume *v, pa_volume_t max) {
+    unsigned c;
+    pa_volume_t t = 0;
+
+    pa_assert(c);
+
+    for (c = 0; c < v->channels; c++)
+        if (v->values[c] > t)
+            t = v->values[c];
+
+    if (t <= 0)
+        return pa_cvolume_set(v, v->channels, max);
+
+    for (c = 0; c < v->channels; c++)
+        v->values[c] = (pa_volume_t) (((uint64_t)  v->values[c] * (uint64_t) max) / (uint64_t) t);
+
+    return v;
+}

src/pulse/volume.h

@@ -244,9 +244,14 @@ float pa_cvolume_get_balance(const pa_channel_map *map, const pa_cvolume *v) PA_
  * operation might not be reversable! Also, after this call
  * pa_cvolume_get_balance() is not guaranteed to actually return the
  * requested balance (e.g. when the input volume was zero anyway for
- * all channels)- \since 0.9.15 */
+ * all channels) \since 0.9.15 */
 pa_cvolume* pa_cvolume_set_balance(const pa_channel_map *map, pa_cvolume *v, float new_balance);
 
+/** Scale the passed pa_cvolume structure so that the maximum volume
+ * of all channels equals max. The proportions between the channel
+ * volumes are kept. \since 0.9.15 */
+pa_cvolume* pa_cvolume_scale(pa_cvolume *v, pa_volume_t max);
+
 PA_C_DECL_END
 
 #endif