libcamera: Add controls serializer

Add a new ControlSerializer helper to serialize and deserialize
ControlInfoMap and ControlList instances. This will be used to implement
the C IPA protocol and the communication with IPA through IPC.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/include/control_serializer.h

@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * control_serializer.h - Control (de)serializer
+ */
+#ifndef __LIBCAMERA_CONTROL_SERIALIZER_H__
+#define __LIBCAMERA_CONTROL_SERIALIZER_H__
+
+#include <map>
+#include <memory>
+#include <vector>
+
+#include <libcamera/controls.h>
+
+namespace libcamera {
+
+class ByteStreamBuffer;
+
+class ControlSerializer
+{
+public:
+	void reset();
+
+	static size_t binarySize(const ControlInfoMap &info);
+	static size_t binarySize(const ControlList &list);
+
+	int serialize(const ControlInfoMap &info, ByteStreamBuffer &buffer);
+	int serialize(const ControlList &list, ByteStreamBuffer &buffer);
+
+	template<typename T>
+	T deserialize(ByteStreamBuffer &buffer);
+
+private:
+	static size_t binarySize(const ControlValue &value);
+	static size_t binarySize(const ControlRange &range);
+
+	static void store(const ControlValue &value, ByteStreamBuffer &buffer);
+	static void store(const ControlRange &range, ByteStreamBuffer &buffer);
+
+	template<typename T>
+	T load(ControlType type, ByteStreamBuffer &b);
+
+	unsigned int serial_;
+	std::vector<std::unique_ptr<ControlId>> controlIds_;
+	std::map<unsigned int, ControlInfoMap> infoMaps_;
+	std::map<const ControlInfoMap *, unsigned int> infoMapHandles_;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_CONTROL_SERIALIZER_H__ */

src/libcamera/include/meson.build

@@ -2,6 +2,7 @@ libcamera_headers = files([
     'byte_stream_buffer.h',
     'camera_controls.h',
     'camera_sensor.h',
+    'control_serializer.h',
     'control_validator.h',
     'device_enumerator.h',
     'device_enumerator_sysfs.h',