Define new AudioControl HAL for automotive.

This provides a mechanism for Android to interact with a car's
audio subsystem.
It is a partial replacement for the deprecated AUDIO_* properties in VehicleHal.
It also provides control over fade/balance.

Bug: 31623564
Test: build for bat_land.  VTS tests in future CL.
Change-Id: I4344cce3a6aa9a28d1327bf4d16bd080c7fd3f50
diff --git a/automotive/audiocontrol/1.0/default/AudioControl.cpp b/automotive/audiocontrol/1.0/default/AudioControl.cpp
new file mode 100644
index 0000000..419225d
--- /dev/null
+++ b/automotive/audiocontrol/1.0/default/AudioControl.cpp
@@ -0,0 +1,86 @@
+#include "AudioControl.h"
+
+#include <hidl/HidlTransportSupport.h>
+#include <log/log.h>
+
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace audiocontrol {
+namespace V1_0 {
+namespace implementation {
+
+
+// This is the static map we're using to associate a ContextNumber with a
+// bus number from the audio_policy_configuration.xml setup.  Every valid context needs
+// to be mapped to a bus address that actually exists in the platforms configuration.
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof(*a))  // Would be nice if this were common...
+static int sContextToBusMap[] = {
+    -1,     // INVALID
+     0,     // MUSIC_CONTEXT
+     1,     // NAVIGATION_CONTEXT
+     2,     // VOICE_COMMAND_CONTEXT
+     3,     // CALL_RING_CONTEXT
+     4,     // CALL_CONTEXT
+     5,     // ALARM_CONTEXT
+     6,     // NOTIFICATION_CONTEXT
+     7,     // SYSTEM_SOUND_CONTEXT
+};
+static const unsigned sContextMapSize = ARRAY_SIZE(sContextToBusMap);
+static const unsigned sContextCount = sContextMapSize - 1;  // Less one for the INVALID entry
+static const unsigned sContextNumberMax = sContextCount;    // contextNumber is counted from 1
+
+
+AudioControl::AudioControl() {
+};
+
+
+// Methods from ::android::hardware::automotive::audiocontrol::V1_0::IAudioControl follow.
+Return<AudioResult> AudioControl::setCallback(const sp<IAudioControlCallback>& notificationObject) {
+    // Hang onto the provided callback object for future use
+    callback = notificationObject;
+
+    return AudioResult::OK;
+}
+
+
+Return<int32_t> AudioControl::getBusForContext(uint32_t contextNumber) {
+    if (contextNumber > sContextNumberMax) {
+        ALOGE("Unexpected context number %d (max expected is %d)", contextNumber, sContextCount);
+        return -1;
+    } else {
+        return sContextToBusMap[contextNumber];
+    }
+}
+
+
+Return<void> AudioControl::setBalanceTowardRight(float value) {
+    // For completeness, lets bounds check the input...
+    if ((value > 1.0f) || (value < -1.0f)) {
+        ALOGE("Balance value out of range -1 to 1 at %0.2f", value);
+    } else {
+        // Just log in this default mock implementation
+        ALOGI("Balance set to %0.2f", value);
+    }
+    return Void();
+}
+
+
+Return<void> AudioControl::setFadeTowardFront(float value) {
+    // For completeness, lets bounds check the input...
+    if ((value > 1.0f) || (value < -1.0f)) {
+        ALOGE("Fader value out of range -1 to 1 at %0.2f", value);
+    } else {
+        // Just log in this default mock implementation
+        ALOGI("Fader set to %0.2f", value);
+    }
+    return Void();
+}
+
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace audiocontrol
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android