automotive/evs/1.1/default/ConfigManager.cpp - android_hardware_interfaces - Gitiles

 /*
  * Copyright (C) 2019 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.
  */

 #include <sstream>
 #include <fstream>
 #include <thread>

 #include <hardware/gralloc.h>
 #include <utils/SystemClock.h>
 #include <android/hardware/camera/device/3.2/ICameraDevice.h>

 #include "ConfigManager.h"

 using ::android::hardware::camera::device::V3_2::StreamRotation;


 ConfigManager::~ConfigManager() {
     /* Nothing to do */
 }


 void ConfigManager::readCameraInfo(const XMLElement * const aCameraElem) {
     if (aCameraElem == nullptr) {
         ALOGW("XML file does not have required camera element");
         return;
     }

     const XMLElement *curElem = aCameraElem->FirstChildElement();
     while (curElem != nullptr) {
         if (!strcmp(curElem->Name(), "group")) {
             /* camera group identifier */
             const char *group_id = curElem->FindAttribute("group_id")->Value();

             /* create CameraGroup */
             unique_ptr<ConfigManager::CameraGroup> aCameraGroup(new ConfigManager::CameraGroup());

             /* add a camera device to its group */
             addCameraDevices(curElem->FindAttribute("device_id")->Value(), aCameraGroup);

             /* a list of camera stream configurations */
             const XMLElement *childElem =
                 curElem->FirstChildElement("caps")->FirstChildElement("stream");
             while (childElem != nullptr) {
                 /* read 5 attributes */
                 const XMLAttribute *idAttr     = childElem->FindAttribute("id");
                 const XMLAttribute *widthAttr  = childElem->FindAttribute("width");
                 const XMLAttribute *heightAttr = childElem->FindAttribute("height");
                 const XMLAttribute *fmtAttr    = childElem->FindAttribute("format");
                 const XMLAttribute *fpsAttr    = childElem->FindAttribute("framerate");

                 const int32_t id = stoi(idAttr->Value());
                 int32_t framerate = 0;
                 if (fpsAttr != nullptr) {
                     framerate = stoi(fpsAttr->Value());
                 }

                 int32_t pixFormat;
                 if (ConfigManagerUtil::convertToPixelFormat(fmtAttr->Value(),
                                                             pixFormat)) {
                     RawStreamConfiguration cfg = {
                         id,
                         stoi(widthAttr->Value()),
                         stoi(heightAttr->Value()),
                         pixFormat,
                         ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS_OUTPUT,
                         framerate
                     };
                     aCameraGroup->streamConfigurations[id] = cfg;
                 }

                 childElem = childElem->NextSiblingElement("stream");
             }

             /* camera group synchronization */
             const char *sync = curElem->FindAttribute("synchronized")->Value();
             aCameraGroup->synchronized =
                 static_cast<bool>(strcmp(sync, "false"));

             /* add a group to hash map */
             mCameraGroups[group_id] = std::move(aCameraGroup);
         } else if (!strcmp(curElem->Name(), "device")) {
             /* camera unique identifier */
             const char *id = curElem->FindAttribute("id")->Value();

             /* camera mount location */
             const char *pos = curElem->FindAttribute("position")->Value();

             /* store read camera module information */
             mCameraInfo[id] = readCameraDeviceInfo(curElem);

             /* assign a camera device to a position group */
             mCameraPosition[pos].emplace(id);
         } else {
             /* ignore other device types */
             ALOGD("Unknown element %s is ignored", curElem->Name());
         }

         curElem = curElem->NextSiblingElement();
     }
 }


 unique_ptr<ConfigManager::CameraInfo>
 ConfigManager::readCameraDeviceInfo(const XMLElement *aDeviceElem) {
     if (aDeviceElem == nullptr) {
         return nullptr;
     }

     /* create a CameraInfo to be filled */
     unique_ptr<ConfigManager::CameraInfo> aCamera(new ConfigManager::CameraInfo());

     /* size information to allocate camera_metadata_t */
     size_t totalEntries = 0;
     size_t totalDataSize = 0;

     /* read device capabilities */
     totalEntries +=
         readCameraCapabilities(aDeviceElem->FirstChildElement("caps"),
                                aCamera,
                                totalDataSize);


     /* read camera metadata */
     totalEntries +=
         readCameraMetadata(aDeviceElem->FirstChildElement("characteristics"),
                            aCamera,
                            totalDataSize);

     /* construct camera_metadata_t */
     if (!constructCameraMetadata(aCamera, totalEntries, totalDataSize)) {
         ALOGW("Either failed to allocate memory or "
               "allocated memory was not large enough");
     }

     return aCamera;
 }


 size_t ConfigManager::readCameraCapabilities(const XMLElement * const aCapElem,
                                              unique_ptr<ConfigManager::CameraInfo> &aCamera,
                                              size_t &dataSize) {
     if (aCapElem == nullptr) {
         return 0;
     }

     string token;
     const XMLElement *curElem = nullptr;

     /* a list of supported camera parameters/controls */
     curElem = aCapElem->FirstChildElement("supported_controls");
     if (curElem != nullptr) {
         const XMLElement *ctrlElem = curElem->FirstChildElement("control");
         while (ctrlElem != nullptr) {
             const char *nameAttr = ctrlElem->FindAttribute("name")->Value();;
             const int32_t minVal = stoi(ctrlElem->FindAttribute("min")->Value());
             const int32_t maxVal = stoi(ctrlElem->FindAttribute("max")->Value());

             int32_t stepVal = 1;
             const XMLAttribute *stepAttr = ctrlElem->FindAttribute("step");
             if (stepAttr != nullptr) {
                 stepVal = stoi(stepAttr->Value());
             }

             CameraParam aParam;
             if (ConfigManagerUtil::convertToEvsCameraParam(nameAttr,
                                                            aParam)) {
                 aCamera->controls.emplace(
                     aParam,
                     make_tuple(minVal, maxVal, stepVal)
                 );
             }

             ctrlElem = ctrlElem->NextSiblingElement("control");
         }
     }

     /* a list of camera stream configurations */
     curElem = aCapElem->FirstChildElement("stream");
     while (curElem != nullptr) {
         /* read 5 attributes */
         const XMLAttribute *idAttr     = curElem->FindAttribute("id");
         const XMLAttribute *widthAttr  = curElem->FindAttribute("width");
         const XMLAttribute *heightAttr = curElem->FindAttribute("height");
         const XMLAttribute *fmtAttr    = curElem->FindAttribute("format");
         const XMLAttribute *fpsAttr    = curElem->FindAttribute("framerate");

         const int32_t id = stoi(idAttr->Value());
         int32_t framerate = 0;
         if (fpsAttr != nullptr) {
             framerate = stoi(fpsAttr->Value());
         }

         int32_t pixFormat;
         if (ConfigManagerUtil::convertToPixelFormat(fmtAttr->Value(),
                                                     pixFormat)) {
             RawStreamConfiguration cfg = {
                 id,
                 stoi(widthAttr->Value()),
                 stoi(heightAttr->Value()),
                 pixFormat,
                 ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS_OUTPUT,
                 framerate
             };
             aCamera->streamConfigurations[id] = cfg;
         }

         curElem = curElem->NextSiblingElement("stream");
     }

     dataSize = calculate_camera_metadata_entry_data_size(
                    get_camera_metadata_tag_type(
                        ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS
                    ),
                    aCamera->streamConfigurations.size() * kStreamCfgSz
                );

     /* a single camera metadata entry contains multiple stream configurations */
     return dataSize > 0 ? 1 : 0;
 }


 size_t ConfigManager::readCameraMetadata(const XMLElement * const aParamElem,
                                        unique_ptr<ConfigManager::CameraInfo> &aCamera,
                                        size_t &dataSize) {
     if (aParamElem == nullptr) {
         return 0;
     }

     const XMLElement *curElem = aParamElem->FirstChildElement("parameter");
     size_t numEntries = 0;
     camera_metadata_tag_t tag;
     while (curElem != nullptr) {
         if (!ConfigManagerUtil::convertToMetadataTag(curElem->FindAttribute("name")->Value(),
                                                      tag)) {
             switch(tag) {
                 case ANDROID_LENS_DISTORTION:
                 case ANDROID_LENS_POSE_ROTATION:
                 case ANDROID_LENS_POSE_TRANSLATION:
                 case ANDROID_LENS_INTRINSIC_CALIBRATION: {
                     /* float[] */
                     size_t count = 0;
                     void   *data = ConfigManagerUtil::convertFloatArray(
                                         curElem->FindAttribute("size")->Value(),
                                         curElem->FindAttribute("value")->Value(),
                                         count
                                    );

                     aCamera->cameraMetadata[tag] =
                         make_pair(make_unique<void *>(data), count);

                     ++numEntries;
                     dataSize += calculate_camera_metadata_entry_data_size(
                                     get_camera_metadata_tag_type(tag), count
                                 );

                     break;
                 }

                 default:
                     ALOGW("Parameter %s is not supported",
                           curElem->FindAttribute("name")->Value());
                     break;
             }
         }

         curElem = curElem->NextSiblingElement("parameter");
     }

     return numEntries;
 }


 bool ConfigManager::constructCameraMetadata(unique_ptr<CameraInfo> &aCamera,
                                             const size_t totalEntries,
                                             const size_t totalDataSize) {
     if (!aCamera->allocate(totalEntries, totalDataSize)) {
         ALOGE("Failed to allocate memory for camera metadata");
         return false;
     }

     const size_t numStreamConfigs = aCamera->streamConfigurations.size();
     unique_ptr<int32_t[]> data(new int32_t[kStreamCfgSz * numStreamConfigs]);
     int32_t *ptr = data.get();
     for (auto &cfg : aCamera->streamConfigurations) {
         for (auto i = 0; i < kStreamCfgSz; ++i) {
           *ptr++ = cfg.second[i];
         }
     }
     int32_t err = add_camera_metadata_entry(aCamera->characteristics,
                                             ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS,
                                             data.get(),
                                             numStreamConfigs * kStreamCfgSz);

     if (err) {
         ALOGE("Failed to add stream configurations to metadata, ignored");
         return false;
     }

     bool success = true;
     for (auto &[tag, entry] : aCamera->cameraMetadata) {
         /* try to add new camera metadata entry */
         int32_t err = add_camera_metadata_entry(aCamera->characteristics,
                                                 tag,
                                                 entry.first.get(),
                                                 entry.second);
         if (err) {
             ALOGE("Failed to add an entry with a tag 0x%X", tag);

             /* may exceed preallocated capacity */
             ALOGE("Camera metadata has %ld / %ld entries and %ld / %ld bytes are filled",
                   (long)get_camera_metadata_entry_count(aCamera->characteristics),
                   (long)get_camera_metadata_entry_capacity(aCamera->characteristics),
                   (long)get_camera_metadata_data_count(aCamera->characteristics),
                   (long)get_camera_metadata_data_capacity(aCamera->characteristics));
             ALOGE("\tCurrent metadata entry requires %ld bytes",
                   (long)calculate_camera_metadata_entry_data_size(tag, entry.second));

             success = false;
         }
     }

     ALOGV("Camera metadata has %ld / %ld entries and %ld / %ld bytes are filled",
           (long)get_camera_metadata_entry_count(aCamera->characteristics),
           (long)get_camera_metadata_entry_capacity(aCamera->characteristics),
           (long)get_camera_metadata_data_count(aCamera->characteristics),
           (long)get_camera_metadata_data_capacity(aCamera->characteristics));

     return success;
 }


 void ConfigManager::readSystemInfo(const XMLElement * const aSysElem) {
     if (aSysElem == nullptr) {
         return;
     }

     /*
      * Please note that this function assumes that a given system XML element
      * and its child elements follow DTD.  If it does not, it will cause a
      * segmentation fault due to the failure of finding expected attributes.
      */

     /* read number of cameras available in the system */
     const XMLElement *xmlElem = aSysElem->FirstChildElement("num_cameras");
     if (xmlElem != nullptr) {
         mSystemInfo.numCameras =
             stoi(xmlElem->FindAttribute("value")->Value());
     }
 }


 void ConfigManager::readDisplayInfo(const XMLElement * const aDisplayElem) {
     if (aDisplayElem == nullptr) {
         ALOGW("XML file does not have required camera element");
         return;
     }

     const XMLElement *curDev = aDisplayElem->FirstChildElement("device");
     while (curDev != nullptr) {
         const char *id = curDev->FindAttribute("id")->Value();
         //const char *pos = curDev->FirstAttribute("position")->Value();

         unique_ptr<DisplayInfo> dpy(new DisplayInfo());
         if (dpy == nullptr) {
             ALOGE("Failed to allocate memory for DisplayInfo");
             return;
         }

         const XMLElement *cap = curDev->FirstChildElement("caps");
         if (cap != nullptr) {
             const XMLElement *curStream = cap->FirstChildElement("stream");
             while (curStream != nullptr) {
                 /* read 4 attributes */
                 const XMLAttribute *idAttr     = curStream->FindAttribute("id");
                 const XMLAttribute *widthAttr  = curStream->FindAttribute("width");
                 const XMLAttribute *heightAttr = curStream->FindAttribute("height");
                 const XMLAttribute *fmtAttr    = curStream->FindAttribute("format");

                 const int32_t id = stoi(idAttr->Value());
                 int32_t pixFormat;
                 if (ConfigManagerUtil::convertToPixelFormat(fmtAttr->Value(),
                                                             pixFormat)) {
                     RawStreamConfiguration cfg = {
                         id,
                         stoi(widthAttr->Value()),
                         stoi(heightAttr->Value()),
                         pixFormat,
                         ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS_INPUT,
                         0   // unused
                     };
                     dpy->streamConfigurations[id] = cfg;
                 }

                 curStream = curStream->NextSiblingElement("stream");
             }
         }

         mDisplayInfo[id] = std::move(dpy);
         curDev = curDev->NextSiblingElement("device");
     }

     return;
 }


 bool ConfigManager::readConfigDataFromXML() noexcept {
     XMLDocument xmlDoc;

     const int64_t parsingStart = android::elapsedRealtimeNano();

     /* load and parse a configuration file */
     xmlDoc.LoadFile(mConfigFilePath);
     if (xmlDoc.ErrorID() != XML_SUCCESS) {
         ALOGE("Failed to load and/or parse a configuration file, %s", xmlDoc.ErrorStr());
         return false;
     }

     /* retrieve the root element */
     const XMLElement *rootElem = xmlDoc.RootElement();
     if (strcmp(rootElem->Name(), "configuration")) {
         ALOGE("A configuration file is not in the required format.  "
               "See /etc/automotive/evs/evs_configuration.dtd");
         return false;
     }

     /*
      * parse camera information; this needs to be done before reading system
      * information
      */
     readCameraInfo(rootElem->FirstChildElement("camera"));

     /* parse system information */
     readSystemInfo(rootElem->FirstChildElement("system"));

     /* parse display information */
     readDisplayInfo(rootElem->FirstChildElement("display"));

     const int64_t parsingEnd = android::elapsedRealtimeNano();
     ALOGI("Parsing configuration file takes %lf (ms)",
           (double)(parsingEnd - parsingStart) / 1000000.0);


     return true;
 }


 void ConfigManager::addCameraDevices(const char *devices,
                                      unique_ptr<CameraGroup> &aGroup) {
     stringstream device_list(devices);
     string token;
     while (getline(device_list, token, ',')) {
         aGroup->devices.emplace(token);
     }
 }


 std::unique_ptr<ConfigManager> ConfigManager::Create(const char *path) {
     unique_ptr<ConfigManager> cfgMgr(new ConfigManager(path));

     /*
      * Read a configuration from XML file
      *
      * If this is too slow, ConfigManager::readConfigDataFromBinary() and
      * ConfigManager::writeConfigDataToBinary()can serialize CameraInfo object
      * to the filesystem and construct CameraInfo instead; this was
      * evaluated as 10x faster.
      */
     if (!cfgMgr->readConfigDataFromXML()) {
         return nullptr;
     } else {
         return cfgMgr;
     }
 }
	/*
	* Copyright (C) 2019 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.
	*/

	#include <sstream>
	#include <fstream>
	#include <thread>

	#include <hardware/gralloc.h>
	#include <utils/SystemClock.h>
	#include <android/hardware/camera/device/3.2/ICameraDevice.h>

	#include "ConfigManager.h"

	using ::android::hardware::camera::device::V3_2::StreamRotation;


	ConfigManager::~ConfigManager() {
	/* Nothing to do */
	}


	void ConfigManager::readCameraInfo(const XMLElement * const aCameraElem) {
	if (aCameraElem == nullptr) {
	ALOGW("XML file does not have required camera element");
	return;
	}

	const XMLElement *curElem = aCameraElem->FirstChildElement();
	while (curElem != nullptr) {
	if (!strcmp(curElem->Name(), "group")) {
	/* camera group identifier */
	const char *group_id = curElem->FindAttribute("group_id")->Value();

	/* create CameraGroup */
	unique_ptr<ConfigManager::CameraGroup> aCameraGroup(new ConfigManager::CameraGroup());

	/* add a camera device to its group */
	addCameraDevices(curElem->FindAttribute("device_id")->Value(), aCameraGroup);

	/* a list of camera stream configurations */
	const XMLElement *childElem =
	curElem->FirstChildElement("caps")->FirstChildElement("stream");
	while (childElem != nullptr) {
	/* read 5 attributes */
	const XMLAttribute *idAttr = childElem->FindAttribute("id");
	const XMLAttribute *widthAttr = childElem->FindAttribute("width");
	const XMLAttribute *heightAttr = childElem->FindAttribute("height");
	const XMLAttribute *fmtAttr = childElem->FindAttribute("format");
	const XMLAttribute *fpsAttr = childElem->FindAttribute("framerate");

	const int32_t id = stoi(idAttr->Value());
	int32_t framerate = 0;
	if (fpsAttr != nullptr) {
	framerate = stoi(fpsAttr->Value());
	}

	int32_t pixFormat;
	if (ConfigManagerUtil::convertToPixelFormat(fmtAttr->Value(),
	pixFormat)) {
	RawStreamConfiguration cfg = {
	id,
	stoi(widthAttr->Value()),
	stoi(heightAttr->Value()),
	pixFormat,
	ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS_OUTPUT,
	framerate
	};
	aCameraGroup->streamConfigurations[id] = cfg;
	}

	childElem = childElem->NextSiblingElement("stream");
	}

	/* camera group synchronization */
	const char *sync = curElem->FindAttribute("synchronized")->Value();
	aCameraGroup->synchronized =
	static_cast<bool>(strcmp(sync, "false"));

	/* add a group to hash map */
	mCameraGroups[group_id] = std::move(aCameraGroup);
	} else if (!strcmp(curElem->Name(), "device")) {
	/* camera unique identifier */
	const char *id = curElem->FindAttribute("id")->Value();

	/* camera mount location */
	const char *pos = curElem->FindAttribute("position")->Value();

	/* store read camera module information */
	mCameraInfo[id] = readCameraDeviceInfo(curElem);

	/* assign a camera device to a position group */
	mCameraPosition[pos].emplace(id);
	} else {
	/* ignore other device types */
	ALOGD("Unknown element %s is ignored", curElem->Name());
	}

	curElem = curElem->NextSiblingElement();
	}
	}


	unique_ptr<ConfigManager::CameraInfo>
	ConfigManager::readCameraDeviceInfo(const XMLElement *aDeviceElem) {
	if (aDeviceElem == nullptr) {
	return nullptr;
	}

	/* create a CameraInfo to be filled */
	unique_ptr<ConfigManager::CameraInfo> aCamera(new ConfigManager::CameraInfo());

	/* size information to allocate camera_metadata_t */
	size_t totalEntries = 0;
	size_t totalDataSize = 0;

	/* read device capabilities */
	totalEntries +=
	readCameraCapabilities(aDeviceElem->FirstChildElement("caps"),
	aCamera,
	totalDataSize);


	/* read camera metadata */
	totalEntries +=
	readCameraMetadata(aDeviceElem->FirstChildElement("characteristics"),
	aCamera,
	totalDataSize);

	/* construct camera_metadata_t */
	if (!constructCameraMetadata(aCamera, totalEntries, totalDataSize)) {
	ALOGW("Either failed to allocate memory or "
	"allocated memory was not large enough");
	}

	return aCamera;
	}


	size_t ConfigManager::readCameraCapabilities(const XMLElement * const aCapElem,
	unique_ptr<ConfigManager::CameraInfo> &aCamera,
	size_t &dataSize) {
	if (aCapElem == nullptr) {
	return 0;
	}

	string token;
	const XMLElement *curElem = nullptr;

	/* a list of supported camera parameters/controls */
	curElem = aCapElem->FirstChildElement("supported_controls");
	if (curElem != nullptr) {
	const XMLElement *ctrlElem = curElem->FirstChildElement("control");
	while (ctrlElem != nullptr) {
	const char *nameAttr = ctrlElem->FindAttribute("name")->Value();;
	const int32_t minVal = stoi(ctrlElem->FindAttribute("min")->Value());
	const int32_t maxVal = stoi(ctrlElem->FindAttribute("max")->Value());

	int32_t stepVal = 1;
	const XMLAttribute *stepAttr = ctrlElem->FindAttribute("step");
	if (stepAttr != nullptr) {
	stepVal = stoi(stepAttr->Value());
	}

	CameraParam aParam;
	if (ConfigManagerUtil::convertToEvsCameraParam(nameAttr,
	aParam)) {
	aCamera->controls.emplace(
	aParam,
	make_tuple(minVal, maxVal, stepVal)
	);
	}

	ctrlElem = ctrlElem->NextSiblingElement("control");
	}
	}

	/* a list of camera stream configurations */
	curElem = aCapElem->FirstChildElement("stream");
	while (curElem != nullptr) {
	/* read 5 attributes */
	const XMLAttribute *idAttr = curElem->FindAttribute("id");
	const XMLAttribute *widthAttr = curElem->FindAttribute("width");
	const XMLAttribute *heightAttr = curElem->FindAttribute("height");
	const XMLAttribute *fmtAttr = curElem->FindAttribute("format");
	const XMLAttribute *fpsAttr = curElem->FindAttribute("framerate");

	const int32_t id = stoi(idAttr->Value());
	int32_t framerate = 0;
	if (fpsAttr != nullptr) {
	framerate = stoi(fpsAttr->Value());
	}

	int32_t pixFormat;
	if (ConfigManagerUtil::convertToPixelFormat(fmtAttr->Value(),
	pixFormat)) {
	RawStreamConfiguration cfg = {
	id,
	stoi(widthAttr->Value()),
	stoi(heightAttr->Value()),
	pixFormat,
	ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS_OUTPUT,
	framerate
	};
	aCamera->streamConfigurations[id] = cfg;
	}

	curElem = curElem->NextSiblingElement("stream");
	}

	dataSize = calculate_camera_metadata_entry_data_size(
	get_camera_metadata_tag_type(
	ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS
	),
	aCamera->streamConfigurations.size() * kStreamCfgSz
	);

	/* a single camera metadata entry contains multiple stream configurations */
	return dataSize > 0 ? 1 : 0;
	}


	size_t ConfigManager::readCameraMetadata(const XMLElement * const aParamElem,
	unique_ptr<ConfigManager::CameraInfo> &aCamera,
	size_t &dataSize) {
	if (aParamElem == nullptr) {
	return 0;
	}

	const XMLElement *curElem = aParamElem->FirstChildElement("parameter");
	size_t numEntries = 0;
	camera_metadata_tag_t tag;
	while (curElem != nullptr) {
	if (!ConfigManagerUtil::convertToMetadataTag(curElem->FindAttribute("name")->Value(),
	tag)) {
	switch(tag) {
	case ANDROID_LENS_DISTORTION:
	case ANDROID_LENS_POSE_ROTATION:
	case ANDROID_LENS_POSE_TRANSLATION:
	case ANDROID_LENS_INTRINSIC_CALIBRATION: {
	/* float[] */
	size_t count = 0;
	void *data = ConfigManagerUtil::convertFloatArray(
	curElem->FindAttribute("size")->Value(),
	curElem->FindAttribute("value")->Value(),
	count
	);

	aCamera->cameraMetadata[tag] =
	make_pair(make_unique<void *>(data), count);

	++numEntries;
	dataSize += calculate_camera_metadata_entry_data_size(
	get_camera_metadata_tag_type(tag), count
	);

	break;
	}

	default:
	ALOGW("Parameter %s is not supported",
	curElem->FindAttribute("name")->Value());
	break;
	}
	}

	curElem = curElem->NextSiblingElement("parameter");
	}

	return numEntries;
	}


	bool ConfigManager::constructCameraMetadata(unique_ptr<CameraInfo> &aCamera,
	const size_t totalEntries,
	const size_t totalDataSize) {
	if (!aCamera->allocate(totalEntries, totalDataSize)) {
	ALOGE("Failed to allocate memory for camera metadata");
	return false;
	}

	const size_t numStreamConfigs = aCamera->streamConfigurations.size();
	unique_ptr<int32_t[]> data(new int32_t[kStreamCfgSz * numStreamConfigs]);
	int32_t *ptr = data.get();
	for (auto &cfg : aCamera->streamConfigurations) {
	for (auto i = 0; i < kStreamCfgSz; ++i) {
	*ptr++ = cfg.second[i];
	}
	}
	int32_t err = add_camera_metadata_entry(aCamera->characteristics,
	ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS,
	data.get(),
	numStreamConfigs * kStreamCfgSz);

	if (err) {
	ALOGE("Failed to add stream configurations to metadata, ignored");
	return false;
	}

	bool success = true;
	for (auto &[tag, entry] : aCamera->cameraMetadata) {
	/* try to add new camera metadata entry */
	int32_t err = add_camera_metadata_entry(aCamera->characteristics,
	tag,
	entry.first.get(),
	entry.second);
	if (err) {
	ALOGE("Failed to add an entry with a tag 0x%X", tag);

	/* may exceed preallocated capacity */
	ALOGE("Camera metadata has %ld / %ld entries and %ld / %ld bytes are filled",
	(long)get_camera_metadata_entry_count(aCamera->characteristics),
	(long)get_camera_metadata_entry_capacity(aCamera->characteristics),
	(long)get_camera_metadata_data_count(aCamera->characteristics),
	(long)get_camera_metadata_data_capacity(aCamera->characteristics));
	ALOGE("\tCurrent metadata entry requires %ld bytes",
	(long)calculate_camera_metadata_entry_data_size(tag, entry.second));

	success = false;
	}
	}

	ALOGV("Camera metadata has %ld / %ld entries and %ld / %ld bytes are filled",
	(long)get_camera_metadata_entry_count(aCamera->characteristics),
	(long)get_camera_metadata_entry_capacity(aCamera->characteristics),
	(long)get_camera_metadata_data_count(aCamera->characteristics),
	(long)get_camera_metadata_data_capacity(aCamera->characteristics));

	return success;
	}


	void ConfigManager::readSystemInfo(const XMLElement * const aSysElem) {
	if (aSysElem == nullptr) {
	return;
	}

	/*
	* Please note that this function assumes that a given system XML element
	* and its child elements follow DTD. If it does not, it will cause a
	* segmentation fault due to the failure of finding expected attributes.
	*/

	/* read number of cameras available in the system */
	const XMLElement *xmlElem = aSysElem->FirstChildElement("num_cameras");
	if (xmlElem != nullptr) {
	mSystemInfo.numCameras =
	stoi(xmlElem->FindAttribute("value")->Value());
	}
	}


	void ConfigManager::readDisplayInfo(const XMLElement * const aDisplayElem) {
	if (aDisplayElem == nullptr) {
	ALOGW("XML file does not have required camera element");
	return;
	}

	const XMLElement *curDev = aDisplayElem->FirstChildElement("device");
	while (curDev != nullptr) {
	const char *id = curDev->FindAttribute("id")->Value();
	//const char *pos = curDev->FirstAttribute("position")->Value();

	unique_ptr<DisplayInfo> dpy(new DisplayInfo());
	if (dpy == nullptr) {
	ALOGE("Failed to allocate memory for DisplayInfo");
	return;
	}

	const XMLElement *cap = curDev->FirstChildElement("caps");
	if (cap != nullptr) {
	const XMLElement *curStream = cap->FirstChildElement("stream");
	while (curStream != nullptr) {
	/* read 4 attributes */
	const XMLAttribute *idAttr = curStream->FindAttribute("id");
	const XMLAttribute *widthAttr = curStream->FindAttribute("width");
	const XMLAttribute *heightAttr = curStream->FindAttribute("height");
	const XMLAttribute *fmtAttr = curStream->FindAttribute("format");

	const int32_t id = stoi(idAttr->Value());
	int32_t pixFormat;
	if (ConfigManagerUtil::convertToPixelFormat(fmtAttr->Value(),
	pixFormat)) {
	RawStreamConfiguration cfg = {
	id,
	stoi(widthAttr->Value()),
	stoi(heightAttr->Value()),
	pixFormat,
	ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS_INPUT,
	0 // unused
	};
	dpy->streamConfigurations[id] = cfg;
	}

	curStream = curStream->NextSiblingElement("stream");
	}
	}

	mDisplayInfo[id] = std::move(dpy);
	curDev = curDev->NextSiblingElement("device");
	}

	return;
	}


	bool ConfigManager::readConfigDataFromXML() noexcept {
	XMLDocument xmlDoc;

	const int64_t parsingStart = android::elapsedRealtimeNano();

	/* load and parse a configuration file */
	xmlDoc.LoadFile(mConfigFilePath);
	if (xmlDoc.ErrorID() != XML_SUCCESS) {
	ALOGE("Failed to load and/or parse a configuration file, %s", xmlDoc.ErrorStr());
	return false;
	}

	/* retrieve the root element */
	const XMLElement *rootElem = xmlDoc.RootElement();
	if (strcmp(rootElem->Name(), "configuration")) {
	ALOGE("A configuration file is not in the required format. "
	"See /etc/automotive/evs/evs_configuration.dtd");
	return false;
	}

	/*
	* parse camera information; this needs to be done before reading system
	* information
	*/
	readCameraInfo(rootElem->FirstChildElement("camera"));

	/* parse system information */
	readSystemInfo(rootElem->FirstChildElement("system"));

	/* parse display information */
	readDisplayInfo(rootElem->FirstChildElement("display"));

	const int64_t parsingEnd = android::elapsedRealtimeNano();
	ALOGI("Parsing configuration file takes %lf (ms)",
	(double)(parsingEnd - parsingStart) / 1000000.0);


	return true;
	}


	void ConfigManager::addCameraDevices(const char *devices,
	unique_ptr<CameraGroup> &aGroup) {
	stringstream device_list(devices);
	string token;
	while (getline(device_list, token, ',')) {
	aGroup->devices.emplace(token);
	}
	}


	std::unique_ptr<ConfigManager> ConfigManager::Create(const char *path) {
	unique_ptr<ConfigManager> cfgMgr(new ConfigManager(path));

	/*
	* Read a configuration from XML file
	*
	* If this is too slow, ConfigManager::readConfigDataFromBinary() and
	* ConfigManager::writeConfigDataToBinary()can serialize CameraInfo object
	* to the filesystem and construct CameraInfo instead; this was
	* evaluated as 10x faster.
	*/
	if (!cfgMgr->readConfigDataFromXML()) {
	return nullptr;
	} else {
	return cfgMgr;
	}
	}