AudioTrack and AudioFlinger send level cleanup
Add an API to control block for getting/setting send level.
This allow us to make the mSendLevel field private.
Document the lack of barriers.
Use 0.0f to initialize floating-point values (for doc only).
Change-Id: I59f83b00adeb89eeee227e7648625d9a835be7a4
diff --git a/include/private/media/AudioTrackShared.h b/include/private/media/AudioTrackShared.h
index 046d5e9..86e0682 100644
--- a/include/private/media/AudioTrackShared.h
+++ b/include/private/media/AudioTrackShared.h
@@ -85,7 +85,9 @@
uint16_t bufferTimeoutMs; // Maximum cumulated timeout before restarting audioflinger
uint16_t waitTimeMs; // Cumulated wait time
- uint16_t sendLevel;
+private:
+ uint16_t mSendLevel; // Fixed point U4.12 so 0x1000 means 1.0
+public:
volatile int32_t flags;
// Cache line boundary (32 bytes)
@@ -98,6 +100,19 @@
uint32_t framesAvailable_l();
uint32_t framesReady();
bool tryLock();
+
+ // No barriers on the following operations, so the ordering of loads/stores
+ // with respect to other parameters is UNPREDICTABLE. That's considered safe.
+
+ // for AudioTrack client only, caller must limit to 0.0 <= sendLevel <= 1.0
+ void setSendLevel(float sendLevel) {
+ mSendLevel = uint16_t(sendLevel * 0x1000);
+ }
+
+ // for AudioFlinger only; the return value must be validated by the caller
+ uint16_t getSendLevel_U4_12() const {
+ return mSendLevel;
+ }
};