usbcamera: initial implementation of default usb camera HAL

* Basic skeleton of usb camera hal implementation
* Vendor tag is not supported yet
* Further usb camera hal implementation can be filled into UsbCamera.cpp
* Hot plug thread need to be implemented

Change-Id: Ida63b6d640e32192f5b60a280d9d5106d80e523f
diff --git a/modules/usbcamera/Metadata.h b/modules/usbcamera/Metadata.h
new file mode 100644
index 0000000..288db16
--- /dev/null
+++ b/modules/usbcamera/Metadata.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2015 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 METADATA_H_
+#define METADATA_H_
+
+#include <stdint.h>
+#include <hardware/camera3.h>
+#include <system/camera_metadata.h>
+
+namespace usb_camera_hal {
+// Metadata is a convenience class for dealing with libcamera_metadata
+class Metadata {
+    public:
+        Metadata();
+        ~Metadata();
+        // Initialize with framework metadata
+        int init(const camera_metadata_t *metadata);
+
+        // Parse and add an entry. Allocates and copies new storage for *data.
+        int addUInt8(uint32_t tag, int count, const uint8_t *data);
+        int add1UInt8(uint32_t tag, const uint8_t data);
+        int addInt32(uint32_t tag, int count, const int32_t *data);
+        int addFloat(uint32_t tag, int count, const float *data);
+        int addInt64(uint32_t tag, int count, const int64_t *data);
+        int addDouble(uint32_t tag, int count, const double *data);
+        int addRational(uint32_t tag, int count,
+                const camera_metadata_rational_t *data);
+
+        // Get a handle to the current metadata
+        // This is not a durable handle, and may be destroyed by add*/init
+        camera_metadata_t* get();
+
+    private:
+        // Actual internal storage
+        camera_metadata_t* mData;
+        // Destroy old metadata and replace with new
+        void replace(camera_metadata_t *m);
+        // Validate the tag, type and count for a metadata entry
+        bool validate(uint32_t tag, int tag_type, int count);
+        // Add a verified tag with data
+        int add(uint32_t tag, int count, const void *tag_data);
+};
+} // namespace usb_camera_hal
+
+#endif // METADATA_H_