libaudiohal: Implement simple HIDL client

This client requires both HIDL client and server to be of the same
ABI version (e.g. 32-bit).

EffectHalHidl::process and EffectHalHidl::processReverse are stubs.

Some extra warnings are logged due to unimplemented functions
in the legacy HAL.

Bug: 30222631
Change-Id: Id074131dec6d6c4f1031695abcf3ea066e92a5af
Test: Play Music (play / EQ), YouTube, Loopback RTLT, Ok Google on N5X
diff --git a/media/libaudiohal/EffectHalHidl.h b/media/libaudiohal/EffectHalHidl.h
new file mode 100644
index 0000000..b79bee0
--- /dev/null
+++ b/media/libaudiohal/EffectHalHidl.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_EFFECT_HAL_HIDL_H
+#define ANDROID_HARDWARE_EFFECT_HAL_HIDL_H
+
+#include <android/hardware/audio/effect/2.0/IEffect.h>
+#include <media/audiohal/EffectHalInterface.h>
+#include <system/audio_effect.h>
+
+using ::android::hardware::audio::effect::V2_0::EffectDescriptor;
+using ::android::hardware::audio::effect::V2_0::IEffect;
+
+namespace android {
+
+class EffectHalHidl : public EffectHalInterface
+{
+  public:
+    // Effect process function. Takes input samples as specified
+    // in input buffer descriptor and output processed samples as specified
+    // in output buffer descriptor.
+    virtual status_t process(audio_buffer_t *inBuffer, audio_buffer_t *outBuffer);
+
+    // Process reverse stream function. This function is used to pass
+    // a reference stream to the effect engine.
+    virtual status_t processReverse(audio_buffer_t *inBuffer, audio_buffer_t *outBuffer);
+
+    // Send a command and receive a response to/from effect engine.
+    virtual status_t command(uint32_t cmdCode, uint32_t cmdSize, void *pCmdData,
+            uint32_t *replySize, void *pReplyData);
+
+    // Returns the effect descriptor.
+    virtual status_t getDescriptor(effect_descriptor_t *pDescriptor);
+
+    uint64_t effectId() const { return mEffectId; }
+
+    static void effectDescriptorToHal(
+            const EffectDescriptor& descriptor, effect_descriptor_t* halDescriptor);
+
+  private:
+    friend class EffectsFactoryHalHidl;
+    sp<IEffect> mEffect;
+    const uint64_t mEffectId;
+
+    static status_t analyzeResult(const hardware::audio::effect::V2_0::Result& result);
+
+    // Can not be constructed directly by clients.
+    EffectHalHidl(const sp<IEffect>& effect, uint64_t effectId);
+
+    // The destructor automatically releases the effect.
+    virtual ~EffectHalHidl();
+};
+
+} // namespace android
+
+#endif // ANDROID_HARDWARE_EFFECT_HAL_HIDL_H