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/ConversionHelperHidl.h b/media/libaudiohal/ConversionHelperHidl.h
new file mode 100644
index 0000000..628913a
--- /dev/null
+++ b/media/libaudiohal/ConversionHelperHidl.h
@@ -0,0 +1,75 @@
+/*
+ * 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_CONVERSION_HELPER_HIDL_H
+#define ANDROID_HARDWARE_CONVERSION_HELPER_HIDL_H
+
+#include <android/hardware/audio/2.0/types.h>
+#include <hidl/HidlSupport.h>
+#include <utils/String8.h>
+
+using ::android::hardware::audio::V2_0::ParameterValue;
+using ::android::hardware::Return;
+using ::android::hardware::Status;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+
+namespace android {
+
+class ConversionHelperHidl {
+  protected:
+    static status_t keysFromHal(const String8& keys, hidl_vec<hidl_string> *hidlKeys);
+    static status_t parametersFromHal(const String8& kvPairs, hidl_vec<ParameterValue> *hidlParams);
+    static void parametersToHal(const hidl_vec<ParameterValue>& parameters, String8 *values);
+
+    ConversionHelperHidl(const char* className);
+
+    status_t processReturn(const char* funcName, const Return<void>& ret) {
+        return processReturn(funcName, ret.getStatus());
+    }
+
+    template<typename R, typename T>
+    status_t processReturn(const char* funcName, const Return<R>& ret, T *retval) {
+        if (ret.getStatus().isOk()) {
+            // This way it also works for enum class to unscoped enum conversion.
+            *retval = static_cast<T>(static_cast<R>(ret));
+            return OK;
+        }
+        return processReturn(funcName, ret.getStatus());
+    }
+
+    status_t processReturn(const char* funcName, const Return<hardware::audio::V2_0::Result>& ret) {
+        return processReturn(funcName, ret, ret);
+    }
+
+    template<typename T>
+    status_t processReturn(
+            const char* funcName, const Return<T>& ret, hardware::audio::V2_0::Result retval) {
+        return processReturn(funcName, ret.getStatus(), retval);
+    }
+
+  private:
+    const char* mClassName;
+
+    static status_t analyzeResult(const hardware::audio::V2_0::Result& result);
+    status_t processReturn(const char* funcName, const Status& status);
+    status_t processReturn(
+            const char* funcName, const Status& status, hardware::audio::V2_0::Result retval);
+};
+
+}  // namespace android
+
+#endif // ANDROID_HARDWARE_CONVERSION_HELPER_HIDL_H