volume: document when arguments of certain functions may overlap

diff --git a/src/pulse/volume.h b/src/pulse/volume.h
index 14692b8d7d7f9043778d61a3d955d84dab1e9498..3881da2f9542fdcfdc7ff7a623f3749fae8f8169 100644 (file)
--- a/src/pulse/volume.h
+++ b/src/pulse/volume.h
@@ -213,11 +213,13 @@ int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v) PA_GCC_PURE
 pa_volume_t pa_sw_volume_multiply(pa_volume_t a, pa_volume_t b) PA_GCC_CONST;
 
 /** Multiply two per-channel volumes and return the result in
- * *dest. This is only valid for software volumes! */
+ * *dest. This is only valid for software volumes! a, b and dest may
+ * point to the same structure. */
 pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b);
 
 /** Multiply a per-channel volume with a scalar volume and return the
- * result in *dest. This is only valid for software volumes! \since
+ * result in *dest. This is only valid for software volumes! a
+ * and dest may point to the same structure. \since
  * 0.9.16 */
 pa_cvolume *pa_sw_cvolume_multiply_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b);
 
@@ -228,11 +230,13 @@ pa_cvolume *pa_sw_cvolume_multiply_scalar(pa_cvolume *dest, const pa_cvolume *a,
 pa_volume_t pa_sw_volume_divide(pa_volume_t a, pa_volume_t b) PA_GCC_CONST;
 
 /** Divide two per-channel volumes and return the result in
- * *dest. This is only valid for software volumes! \since 0.9.13 */
+ * *dest. This is only valid for software volumes! a, b
+ * and dest may point to the same structure. \since 0.9.13 */
 pa_cvolume *pa_sw_cvolume_divide(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b);
 
 /** Divide a per-channel volume by a scalar volume and return the
- * result in *dest. This is only valid for software volumes! \since
+ * result in *dest. This is only valid for software volumes! a
+ * and dest may point to the same structure. \since
  * 0.9.16 */
 pa_cvolume *pa_sw_cvolume_divide_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b);