sdlog2 logger app added. New flexible log format, compatible with APM.

7 files changed, 1323 insertions, 0 deletions

diff --git a/makefiles/config_px4fmu_default.mk b/makefiles/config_px4fmu_default.mk
index 1e4d59266..b6fa4014a 100644
--- a/makefiles/config_px4fmu_default.mk
+++ b/makefiles/config_px4fmu_default.mk
@@ -78,6 +78,7 @@ MODULES		+= modules/multirotor_pos_control
 # Logging
 #
 MODULES		+= modules/sdlog
+MODULES		+= modules/sdlog2
 
 #
 # Library modules
diff --git a/src/modules/sdlog2/module.mk b/src/modules/sdlog2/module.mk
new file mode 100644
index 000000000..5a9936635
--- /dev/null
+++ b/src/modules/sdlog2/module.mk
@@ -0,0 +1,43 @@
+############################################################################
+#
+#   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name PX4 nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+#
+# sdlog2 Application
+#
+
+MODULE_COMMAND  = sdlog2
+# The main thread only buffers to RAM, needs a high priority
+MODULE_PRIORITY = "SCHED_PRIORITY_MAX-30"
+
+SRCS = sdlog2.c \
+       sdlog2_ringbuffer.c
diff --git a/src/modules/sdlog2/sdlog2.c b/src/modules/sdlog2/sdlog2.c
new file mode 100644
index 000000000..38b57082f
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2.c
@@ -0,0 +1,890 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+ *   Author: Lorenz Meier <lm@inf.ethz.ch>
+ *           Anton Babushkin <rk3dov@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sdlog2.c
+ *
+ * Simple SD logger for flight data. Buffers new sensor values and
+ * does the heavy SD I/O in a low-priority worker thread.
+ *
+ * @author Lorenz Meier <lm@inf.ethz.ch>
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/prctl.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <systemlib/err.h>
+#include <unistd.h>
+#include <drivers/drv_hrt.h>
+
+#include <uORB/uORB.h>
+#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/vehicle_attitude.h>
+#include <uORB/topics/vehicle_attitude_setpoint.h>
+#include <uORB/topics/actuator_outputs.h>
+#include <uORB/topics/actuator_controls.h>
+#include <uORB/topics/actuator_controls_effective.h>
+#include <uORB/topics/vehicle_command.h>
+#include <uORB/topics/vehicle_local_position.h>
+#include <uORB/topics/vehicle_global_position.h>
+#include <uORB/topics/vehicle_gps_position.h>
+#include <uORB/topics/vehicle_vicon_position.h>
+#include <uORB/topics/optical_flow.h>
+#include <uORB/topics/battery_status.h>
+#include <uORB/topics/differential_pressure.h>
+#include <uORB/topics/airspeed.h>
+
+#include <systemlib/systemlib.h>
+
+#include <mavlink/mavlink_log.h>
+
+#include "sdlog2_ringbuffer.h"
+#include "sdlog2_messages.h"
+
+static bool thread_should_exit = false;		/**< Deamon exit flag */
+static bool thread_running = false;		/**< Deamon status flag */
+static int deamon_task;				/**< Handle of deamon task / thread */
+static const int MAX_NO_LOGFOLDER = 999;	/**< Maximum number of log folders */
+static const int LOG_BUFFER_SIZE = 2048;
+static const int MAX_WRITE_CHUNK = 1024;
+
+static const char *mountpoint = "/fs/microsd";
+int log_file = -1;
+int mavlink_fd = -1;
+struct sdlog2_logbuffer lb;
+
+/* mutex / condition to synchronize threads */
+pthread_mutex_t logbuffer_mutex;
+pthread_cond_t logbuffer_cond;
+
+/**
+ * System state vector log buffer writing
+ */
+static void *sdlog2_logbuffer_write_thread(void *arg);
+
+/**
+ * Create the thread to write the system vector
+ */
+pthread_t sdlog2_logwriter_start(struct sdlog2_logbuffer *logbuf);
+
+/**
+ * Write a header to log file: list of message formats
+ */
+void sdlog2_write_formats(int fd);
+
+/**
+ * SD log management function.
+ */
+__EXPORT int sdlog2_main(int argc, char *argv[]);
+
+/**
+ * Mainloop of sd log deamon.
+ */
+int sdlog2_thread_main(int argc, char *argv[]);
+
+/**
+ * Print the correct usage.
+ */
+static void usage(const char *reason);
+
+static int file_exist(const char *filename);
+
+static int file_copy(const char *file_old, const char *file_new);
+
+static void handle_command(struct vehicle_command_s *cmd);
+
+/**
+ * Print the current status.
+ */
+static void print_sdlog2_status(void);
+
+/**
+ * Create folder for current logging session.
+ */
+static int create_logfolder(char *folder_path);
+
+static void
+usage(const char *reason)
+{
+	if (reason)
+		fprintf(stderr, "%s\n", reason);
+
+	errx(1, "usage: sdlog2 {start|stop|status} [-s <number of skipped lines>]\n\n");
+}
+
+unsigned long log_bytes_written = 0;
+uint64_t starttime = 0;
+
+/* logging on or off, default to true */
+bool logging_enabled = true;
+
+/**
+ * The sd log deamon app only briefly exists to start
+ * the background job. The stack size assigned in the
+ * Makefile does only apply to this management task.
+ *
+ * The actual stack size should be set in the call
+ * to task_spawn().
+ */
+int sdlog2_main(int argc, char *argv[])
+{
+	if (argc < 1)
+		usage("missing command");
+
+	if (!strcmp(argv[1], "start")) {
+
+		if (thread_running) {
+			printf("sdlog2 already running\n");
+			/* this is not an error */
+			exit(0);
+		}
+
+		thread_should_exit = false;
+		deamon_task = task_spawn("sdlog2",
+					 SCHED_DEFAULT,
+					 SCHED_PRIORITY_DEFAULT - 30,
+					 4096,
+					 sdlog2_thread_main,
+					 (const char **)argv);
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		if (!thread_running) {
+			printf("\tsdlog2 is not started\n");
+		}
+
+		thread_should_exit = true;
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (thread_running) {
+			print_sdlog2_status();
+
+		} else {
+			printf("\tsdlog2 not started\n");
+		}
+
+		exit(0);
+	}
+
+	usage("unrecognized command");
+	exit(1);
+}
+
+int create_logfolder(char *folder_path)
+{
+	/* make folder on sdcard */
+	uint16_t foldernumber = 1; // start with folder 0001
+	int mkdir_ret;
+
+	/* look for the next folder that does not exist */
+	while (foldernumber < MAX_NO_LOGFOLDER) {
+		/* set up file path: e.g. /mnt/sdcard/sensorfile0001.txt */
+		sprintf(folder_path, "%s/session%04u", mountpoint, foldernumber);
+		mkdir_ret = mkdir(folder_path, S_IRWXU | S_IRWXG | S_IRWXO);
+		/* the result is -1 if the folder exists */
+
+		if (mkdir_ret == 0) {
+			/* folder does not exist, success */
+
+			/* copy parser script file */
+			// TODO
+			/*
+			char mfile_out[100];
+			sprintf(mfile_out, "%s/session%04u/run_to_plot_data.m", mountpoint, foldernumber);
+			int ret = file_copy(mfile_in, mfile_out);
+
+			if (!ret) {
+				warnx("copied m file to %s", mfile_out);
+
+			} else {
+				warnx("failed copying m file from %s to\n %s", mfile_in, mfile_out);
+			}
+			*/
+
+			break;
+
+		} else if (mkdir_ret == -1) {
+			/* folder exists already */
+			foldernumber++;
+			continue;
+
+		} else {
+			warn("failed creating new folder");
+			return -1;
+		}
+	}
+
+	if (foldernumber >= MAX_NO_LOGFOLDER) {
+		/* we should not end up here, either we have more than MAX_NO_LOGFOLDER on the SD card, or another problem */
+		warn("all %d possible folders exist already", MAX_NO_LOGFOLDER);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void *
+sdlog2_logbuffer_write_thread(void *arg)
+{
+	/* set name */
+	prctl(PR_SET_NAME, "sdlog2 microSD I/O", 0);
+
+	struct sdlog2_logbuffer *logbuf = (struct sdlog2_logbuffer *)arg;
+
+	int poll_count = 0;
+
+	void *read_ptr;
+	int n = 0;
+
+	while (!thread_should_exit) {
+
+		/* make sure threads are synchronized */
+		pthread_mutex_lock(&logbuffer_mutex);
+
+		/* update read pointer if needed */
+		if (n > 0) {
+			sdlog2_logbuffer_mark_read(&lb, n);
+		}
+
+		/* only wait if no data is available to process */
+		if (sdlog2_logbuffer_is_empty(logbuf)) {
+			/* blocking wait for new data at this line */
+			pthread_cond_wait(&logbuffer_cond, &logbuffer_mutex);
+		}
+
+		/* only get pointer to thread-safe data, do heavy I/O a few lines down */
+		n = sdlog2_logbuffer_get_ptr(logbuf, &read_ptr);
+
+		/* continue */
+		pthread_mutex_unlock(&logbuffer_mutex);
+
+		if (n > 0) {
+			/* do heavy IO here */
+			if (n > MAX_WRITE_CHUNK)
+				n = MAX_WRITE_CHUNK;
+
+			n = write(log_file, read_ptr, n);
+
+			if (n > 0) {
+				log_bytes_written += n;
+			}
+		}
+
+		if (poll_count % 100 == 0) {
+			fsync(log_file);
+		}
+
+		poll_count++;
+	}
+
+	fsync(log_file);
+
+	return OK;
+}
+
+pthread_t sdlog2_logwriter_start(struct sdlog2_logbuffer *logbuf)
+{
+	pthread_attr_t receiveloop_attr;
+	pthread_attr_init(&receiveloop_attr);
+
+	struct sched_param param;
+	/* low priority, as this is expensive disk I/O */
+	param.sched_priority = SCHED_PRIORITY_DEFAULT - 40;
+	(void)pthread_attr_setschedparam(&receiveloop_attr, &param);
+
+	pthread_attr_setstacksize(&receiveloop_attr, 2048);
+
+	pthread_t thread;
+	pthread_create(&thread, &receiveloop_attr, sdlog2_logbuffer_write_thread, logbuf);
+	return thread;
+
+	// XXX we have to destroy the attr at some point
+}
+
+void sdlog2_write_formats(int fd)
+{
+	/* construct message format packet */
+	struct {
+		LOG_PACKET_HEADER;
+		struct log_format_s body;
+	} log_format_packet = {
+		LOG_PACKET_HEADER_INIT(LOG_FORMAT_MSG),
+	};
+
+	/* fill message format packet for each format and write to log */
+	int i;
+
+	for (i = 0; i < log_formats_num; i++) {
+		log_format_packet.body = log_formats[i];
+		write(fd, &log_format_packet, sizeof(log_format_packet));
+	}
+
+	fsync(fd);
+}
+
+int sdlog2_thread_main(int argc, char *argv[])
+{
+	mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);
+
+	if (mavlink_fd < 0) {
+		warnx("ERROR: Failed to open MAVLink log stream, start mavlink app first.\n");
+	}
+
+	/* log every n'th value (skip three per default) */
+	int skip_value = 3;
+
+	/* work around some stupidity in task_create's argv handling */
+	argc -= 2;
+	argv += 2;
+	int ch;
+
+	while ((ch = getopt(argc, argv, "s:r")) != EOF) {
+		switch (ch) {
+		case 's': {
+				/* log only every n'th (gyro clocked) value */
+				unsigned s = strtoul(optarg, NULL, 10);
+
+				if (s < 1 || s > 250) {
+					errx(1, "Wrong skip value of %d, out of range (1..250)\n", s);
+
+				} else {
+					skip_value = s;
+				}
+			}
+			break;
+
+		case 'r':
+			/* log only on request, disable logging per default */
+			logging_enabled = false;
+			break;
+
+		case '?':
+			if (optopt == 'c') {
+				warnx("Option -%c requires an argument.\n", optopt);
+
+			} else if (isprint(optopt)) {
+				warnx("Unknown option `-%c'.\n", optopt);
+
+			} else {
+				warnx("Unknown option character `\\x%x'.\n", optopt);
+			}
+
+		default:
+			usage("unrecognized flag");
+			errx(1, "exiting.");
+		}
+	}
+
+	if (file_exist(mountpoint) != OK) {
+		errx(1, "logging mount point %s not present, exiting.", mountpoint);
+	}
+
+	char folder_path[64];
+
+	if (create_logfolder(folder_path))
+		errx(1, "unable to create logging folder, exiting.");
+
+	/* string to hold the path to the sensorfile */
+	char path_buf[64] = "";
+
+	/* only print logging path, important to find log file later */
+	warnx("logging to directory %s\n", folder_path);
+
+	/* set up file path: e.g. /mnt/sdcard/session0001/actuator_controls0.bin */
+	sprintf(path_buf, "%s/%s.bin", folder_path, "log");
+
+	if (0 == (log_file = open(path_buf, O_CREAT | O_WRONLY | O_DSYNC))) {
+		errx(1, "opening %s failed.\n", path_buf);
+	}
+
+	/* write log messages formats */
+	sdlog2_write_formats(log_file);
+
+	/* --- IMPORTANT: DEFINE NUMBER OF ORB STRUCTS TO WAIT FOR HERE --- */
+	/* number of messages */
+	const ssize_t fdsc = 25;
+	/* Sanity check variable and index */
+	ssize_t fdsc_count = 0;
+	/* file descriptors to wait for */
+	struct pollfd fds[fdsc];
+
+	/* warning! using union here to save memory, elements should be used separately! */
+	union {
+		struct sensor_combined_s raw;
+		struct vehicle_attitude_s att;
+		struct vehicle_attitude_setpoint_s att_sp;
+		struct actuator_outputs_s act_outputs;
+		struct actuator_controls_s act_controls;
+		struct actuator_controls_effective_s act_controls_effective;
+		struct vehicle_command_s cmd;
+		struct vehicle_local_position_s local_pos;
+		struct vehicle_global_position_s global_pos;
+		struct vehicle_gps_position_s gps_pos;
+		struct vehicle_vicon_position_s vicon_pos;
+		struct optical_flow_s flow;
+		struct battery_status_s batt;
+		struct differential_pressure_s diff_pres;
+		struct airspeed_s airspeed;
+	} buf;
+	memset(&buf, 0, sizeof(buf));
+
+	struct {
+		int cmd_sub;
+		int sensor_sub;
+		int att_sub;
+		int att_sp_sub;
+		int act_0_sub;
+		int controls_0_sub;
+		int controls_effective_0_sub;
+		int local_pos_sub;
+		int global_pos_sub;
+		int gps_pos_sub;
+		int vicon_pos_sub;
+		int flow_sub;
+		int batt_sub;
+		int diff_pres_sub;
+		int airspeed_sub;
+	} subs;
+
+	/* log message buffer: header + body */
+	struct {
+		LOG_PACKET_HEADER;
+		union {
+			struct log_TS_s log_TS;
+			struct log_ATT_s log_ATT;
+			struct log_RAW_s log_RAW;
+		} body;
+	} log_msg = {
+		LOG_PACKET_HEADER_INIT(0)
+	};
+	memset(&log_msg.body, 0, sizeof(log_msg.body));
+
+	/* --- MANAGEMENT - LOGGING COMMAND --- */
+	/* subscribe to ORB for vehicle command */
+	subs.cmd_sub = orb_subscribe(ORB_ID(vehicle_command));
+	fds[fdsc_count].fd = subs.cmd_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- GPS POSITION --- */
+	/* subscribe to ORB for global position */
+	subs.gps_pos_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
+	fds[fdsc_count].fd = subs.gps_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- SENSORS RAW VALUE --- */
+	/* subscribe to ORB for sensors raw */
+	subs.sensor_sub = orb_subscribe(ORB_ID(sensor_combined));
+	fds[fdsc_count].fd = subs.sensor_sub;
+	/* do not rate limit, instead use skip counter (aliasing on rate limit) */
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ATTITUDE VALUE --- */
+	/* subscribe to ORB for attitude */
+	subs.att_sub = orb_subscribe(ORB_ID(vehicle_attitude));
+	fds[fdsc_count].fd = subs.att_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ATTITUDE SETPOINT VALUE --- */
+	/* subscribe to ORB for attitude setpoint */
+	/* struct already allocated */
+	subs.att_sp_sub = orb_subscribe(ORB_ID(vehicle_attitude_setpoint));
+	fds[fdsc_count].fd = subs.att_sp_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/** --- ACTUATOR OUTPUTS --- */
+	subs.act_0_sub = orb_subscribe(ORB_ID(actuator_outputs_0));
+	fds[fdsc_count].fd = subs.act_0_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ACTUATOR CONTROL VALUE --- */
+	/* subscribe to ORB for actuator control */
+	subs.controls_0_sub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS);
+	fds[fdsc_count].fd = subs.controls_0_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ACTUATOR CONTROL EFFECTIVE VALUE --- */
+	/* subscribe to ORB for actuator control */
+	subs.controls_effective_0_sub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS_EFFECTIVE);
+	fds[fdsc_count].fd = subs.controls_effective_0_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- LOCAL POSITION --- */
+	/* subscribe to ORB for local position */
+	subs.local_pos_sub = orb_subscribe(ORB_ID(vehicle_local_position));
+	fds[fdsc_count].fd = subs.local_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- GLOBAL POSITION --- */
+	/* subscribe to ORB for global position */
+	subs.global_pos_sub = orb_subscribe(ORB_ID(vehicle_global_position));
+	fds[fdsc_count].fd = subs.global_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- VICON POSITION --- */
+	/* subscribe to ORB for vicon position */
+	subs.vicon_pos_sub = orb_subscribe(ORB_ID(vehicle_vicon_position));
+	fds[fdsc_count].fd = subs.vicon_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- FLOW measurements --- */
+	/* subscribe to ORB for flow measurements */
+	subs.flow_sub = orb_subscribe(ORB_ID(optical_flow));
+	fds[fdsc_count].fd = subs.flow_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- BATTERY STATUS --- */
+	/* subscribe to ORB for flow measurements */
+	subs.batt_sub = orb_subscribe(ORB_ID(battery_status));
+	fds[fdsc_count].fd = subs.batt_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- DIFFERENTIAL PRESSURE --- */
+	/* subscribe to ORB for flow measurements */
+	subs.diff_pres_sub = orb_subscribe(ORB_ID(differential_pressure));
+	fds[fdsc_count].fd = subs.diff_pres_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- AIRSPEED --- */
+	/* subscribe to ORB for airspeed */
+	subs.airspeed_sub = orb_subscribe(ORB_ID(airspeed));
+	fds[fdsc_count].fd = subs.airspeed_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* WARNING: If you get the error message below,
+	 * then the number of registered messages (fdsc)
+	 * differs from the number of messages in the above list.
+	 */
+	if (fdsc_count > fdsc) {
+		warn("WARNING: Not enough space for poll fds allocated. Check %s:%d.\n", __FILE__, __LINE__);
+		fdsc_count = fdsc;
+	}
+
+	/*
+	 * set up poll to block for new data,
+	 * wait for a maximum of 1000 ms (1 second)
+	 */
+	// const int timeout = 1000;
+
+	thread_running = true;
+
+	/* initialize log buffer with specified size */
+	sdlog2_logbuffer_init(&lb, LOG_BUFFER_SIZE);
+
+	/* initialize thread synchronization */
+	pthread_mutex_init(&logbuffer_mutex, NULL);
+	pthread_cond_init(&logbuffer_cond, NULL);
+
+	/* start logbuffer emptying thread */
+	pthread_t logwriter_pthread = sdlog2_logwriter_start(&lb);
+
+	starttime = hrt_absolute_time();
+
+	/* track skipping */
+	int skip_count = 0;
+
+	while (!thread_should_exit) {
+
+		/* poll all topics */
+		int poll_ret = poll(fds, 4, 1000);
+
+		/* handle the poll result */
+		if (poll_ret == 0) {
+			/* XXX this means none of our providers is giving us data - might be an error? */
+		} else if (poll_ret < 0) {
+			/* XXX this is seriously bad - should be an emergency */
+		} else {
+
+			int ifds = 0;
+
+			if (!logging_enabled) {
+				usleep(100000);
+				continue;
+			}
+
+			pthread_mutex_lock(&logbuffer_mutex);
+
+			/* write time stamp message */
+			log_msg.msg_type = LOG_TS_MSG;
+			log_msg.body.log_TS.t = hrt_absolute_time();
+			sdlog2_logbuffer_write(&lb, &log_msg, LOG_PACKET_SIZE(TS));
+
+			/* --- VEHICLE COMMAND VALUE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				/* copy command into local buffer */
+				orb_copy(ORB_ID(vehicle_command), subs.cmd_sub, &buf.cmd);
+				handle_command(&buf.cmd);
+			}
+
+			/* --- GPS POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+			}
+
+			/* --- SENSORS RAW VALUE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(sensor_combined), subs.sensor_sub, &buf.raw);
+				log_msg.msg_type = LOG_RAW_MSG;
+				log_msg.body.log_RAW.accX = buf.raw.accelerometer_m_s2[0];
+				log_msg.body.log_RAW.accY = buf.raw.accelerometer_m_s2[1];
+				log_msg.body.log_RAW.accZ = buf.raw.accelerometer_m_s2[2];
+				sdlog2_logbuffer_write(&lb, &log_msg, LOG_PACKET_SIZE(RAW));
+			}
+
+			/* --- ATTITUDE VALUE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_attitude), subs.att_sub, &buf.att);
+				log_msg.msg_type = LOG_ATT_MSG;
+				log_msg.body.log_ATT.roll = buf.att.roll;
+				log_msg.body.log_ATT.pitch = buf.att.pitch;
+				log_msg.body.log_ATT.yaw = buf.att.yaw;
+				sdlog2_logbuffer_write(&lb, &log_msg, LOG_PACKET_SIZE(ATT));
+			}
+
+			/* --- ATTITUDE SETPOINT VALUE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_attitude_setpoint), subs.att_sp_sub, &buf.att_sp);
+				// TODO not implemented yet
+			}
+
+			/* --- ACTUATOR OUTPUTS --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- ACTUATOR CONTROL VALUE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- ACTUATOR CONTROL EFFECTIVE VALUE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- LOCAL POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- GLOBAL POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- VICON POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- FLOW measurements --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- BATTERY STATUS --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- DIFFERENTIAL PRESSURE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- AIRSPEED --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				// TODO not implemented yet
+			}
+
+			/* signal the other thread new data, but not yet unlock */
+			if (sdlog2_logbuffer_count(&lb) > (lb.size / 2)) {
+				/* only request write if several packets can be written at once */
+				pthread_cond_signal(&logbuffer_cond);
+			}
+
+			/* unlock, now the writer thread may run */
+			pthread_mutex_unlock(&logbuffer_mutex);
+		}
+	}
+
+	print_sdlog2_status();
+
+	/* wake up write thread one last time */
+	pthread_mutex_lock(&logbuffer_mutex);
+	pthread_cond_signal(&logbuffer_cond);
+	/* unlock, now the writer thread may return */
+	pthread_mutex_unlock(&logbuffer_mutex);
+
+	/* wait for write thread to return */
+	(void)pthread_join(logwriter_pthread, NULL);
+
+	pthread_mutex_destroy(&logbuffer_mutex);
+	pthread_cond_destroy(&logbuffer_cond);
+
+	warnx("exiting.\n\n");
+
+	thread_running = false;
+
+	return 0;
+}
+
+void print_sdlog2_status()
+{
+	float mebibytes = log_bytes_written / 1024.0f / 1024.0f;
+	float seconds = ((float)(hrt_absolute_time() - starttime)) / 1000000.0f;
+
+	warnx("wrote %4.2f MiB (average %5.3f MiB/s).\n", (double)mebibytes, (double)(mebibytes / seconds));
+}
+
+/**
+ * @return 0 if file exists
+ */
+int file_exist(const char *filename)
+{
+	struct stat buffer;
+	return stat(filename, &buffer);
+}
+
+int file_copy(const char *file_old, const char *file_new)
+{
+	FILE *source, *target;
+	source = fopen(file_old, "r");
+	int ret = 0;
+
+	if (source == NULL) {
+		warnx("failed opening input file to copy");
+		return 1;
+	}
+
+	target = fopen(file_new, "w");
+
+	if (target == NULL) {
+		fclose(source);
+		warnx("failed to open output file to copy");
+		return 1;
+	}
+
+	char buf[128];
+	int nread;
+
+	while ((nread = fread(buf, 1, sizeof(buf), source)) > 0) {
+		ret = fwrite(buf, 1, nread, target);
+
+		if (ret <= 0) {
+			warnx("error writing file");
+			ret = 1;
+			break;
+		}
+	}
+
+	fsync(fileno(target));
+
+	fclose(source);
+	fclose(target);
+
+	return ret;
+}
+
+void handle_command(struct vehicle_command_s *cmd)
+{
+	/* result of the command */
+	uint8_t result = VEHICLE_CMD_RESULT_UNSUPPORTED;
+
+	/* request to set different system mode */
+	switch (cmd->command) {
+
+	case VEHICLE_CMD_PREFLIGHT_STORAGE:
+
+		if (((int)(cmd->param3)) == 1)	{
+
+			/* enable logging */
+			mavlink_log_info(mavlink_fd, "[log] file:");
+			mavlink_log_info(mavlink_fd, "logdir");
+			logging_enabled = true;
+		}
+
+		if (((int)(cmd->param3)) == 0)	{
+
+			/* disable logging */
+			mavlink_log_info(mavlink_fd, "[log] stopped.");
+			logging_enabled = false;
+		}
+
+		break;
+
+	default:
+		/* silently ignore */
+		break;
+	}
+
+}
diff --git a/src/modules/sdlog2/sdlog2_format.h b/src/modules/sdlog2/sdlog2_format.h
new file mode 100644
index 000000000..f5347a7bd
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2_format.h
@@ -0,0 +1,98 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sdlog2_format.h
+ *
+ * General log format structures and macro.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+/*
+Format characters in the format string for binary log messages
+  b   : int8_t
+  B   : uint8_t
+  h   : int16_t
+  H   : uint16_t
+  i   : int32_t
+  I   : uint32_t
+  f   : float
+  n   : char[4]
+  N   : char[16]
+  Z   : char[64]
+  c   : int16_t * 100
+  C   : uint16_t * 100
+  e   : int32_t * 100
+  E   : uint32_t * 100
+  L   : int32_t latitude/longitude
+  M   : uint8_t flight mode
+
+  q   : int64_t
+  Q   : uint64_t
+ */
+
+#ifndef SDLOG2_FORMAT_H_
+#define SDLOG2_FORMAT_H_
+
+#define LOG_PACKET_HEADER_LEN	   3
+#define LOG_PACKET_HEADER	       uint8_t head1, head2, msg_type;
+#define LOG_PACKET_HEADER_INIT(id) .head1 = HEAD_BYTE1, .head2 = HEAD_BYTE2, .msg_type = id
+
+// once the logging code is all converted we will remove these from
+// this header
+#define HEAD_BYTE1  0xA3    // Decimal 163
+#define HEAD_BYTE2  0x95    // Decimal 149
+
+struct log_format_s {
+	uint8_t type;
+	uint8_t length;
+	char name[4];
+	char format[16];
+	char labels[64];
+};
+
+#define LOG_FORMAT(_name, _format, _labels) { \
+		.type = LOG_##_name##_MSG, \
+			.length = sizeof(struct log_##_name##_s) + 8, \
+				  .name = #_name, \
+					  .format = _format, \
+						    .labels = _labels \
+	}
+
+#define LOG_FORMAT_MSG	  128
+
+#define LOG_PACKET_SIZE(_name)	LOG_PACKET_HEADER_LEN + sizeof(log_msg.body.log_##_name)
+
+#endif /* SDLOG2_FORMAT_H_ */
diff --git a/src/modules/sdlog2/sdlog2_messages.h b/src/modules/sdlog2/sdlog2_messages.h
new file mode 100644
index 000000000..ae98ea038
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2_messages.h
@@ -0,0 +1,82 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sdlog2_messages.h
+ *
+ * Log messages and structures definition.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#ifndef SDLOG2_MESSAGES_H_
+#define SDLOG2_MESSAGES_H_
+
+#include "sdlog2_format.h"
+
+/* define message formats */
+
+/* === 1: TS - TIME STAMP === */
+#define LOG_TS_MSG 1
+struct log_TS_s {
+	uint64_t t;
+};
+
+/* === 2: ATT - ATTITUDE === */
+#define LOG_ATT_MSG 2
+struct log_ATT_s {
+	float roll;
+	float pitch;
+	float yaw;
+};
+
+/* === 3: RAW - SENSORS === */
+#define LOG_RAW_MSG 3
+struct log_RAW_s {
+	float accX;
+	float accY;
+	float accZ;
+};
+
+/* construct list of all message formats */
+
+static const struct log_format_s log_formats[] = {
+	LOG_FORMAT(TS, "Q", "t"),
+	LOG_FORMAT(ATT, "fff", "roll,pitch,yaw"),
+	LOG_FORMAT(RAW, "fff", "accX,accY,accZ"),
+};
+
+static const int log_formats_num = sizeof(log_formats) / sizeof(struct log_format_s);
+
+#endif /* SDLOG2_MESSAGES_H_ */
diff --git a/src/modules/sdlog2/sdlog2_ringbuffer.c b/src/modules/sdlog2/sdlog2_ringbuffer.c
new file mode 100644
index 000000000..022a183ba
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2_ringbuffer.c
@@ -0,0 +1,141 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sdlog2_ringbuffer.c
+ *
+ * Ring FIFO buffer for binary data.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "sdlog2_ringbuffer.h"
+
+void sdlog2_logbuffer_init(struct sdlog2_logbuffer *lb, int size)
+{
+	lb->size  = size;
+	lb->write_ptr = 0;
+	lb->read_ptr = 0;
+	lb->data = malloc(lb->size);
+}
+
+int sdlog2_logbuffer_free(struct sdlog2_logbuffer *lb)
+{
+	int n = lb->read_ptr - lb->write_ptr - 1;
+
+	if (n < 0) {
+		n += lb->size;
+	}
+
+	return n;
+}
+
+int sdlog2_logbuffer_count(struct sdlog2_logbuffer *lb)
+{
+	int n = lb->write_ptr - lb->read_ptr;
+
+	if (n < 0) {
+		n += lb->size;
+	}
+
+	return n;
+}
+
+int sdlog2_logbuffer_is_empty(struct sdlog2_logbuffer *lb)
+{
+	return lb->read_ptr == lb->write_ptr;
+}
+
+void sdlog2_logbuffer_write(struct sdlog2_logbuffer *lb, void *ptr, int size)
+{
+	// bytes available to write
+	int available = lb->read_ptr - lb->write_ptr - 1;
+
+	if (available < 0)
+		available += lb->size;
+
+	if (size > available) {
+		// buffer overflow
+		return;
+	}
+
+	char *c = (char *) ptr;
+	int n = lb->size - lb->write_ptr;	// bytes to end of the buffer
+
+	if (n < size) {
+		// message goes over end of the buffer
+		memcpy(&(lb->data[lb->write_ptr]), c, n);
+		lb->write_ptr = 0;
+
+	} else {
+		n = 0;
+	}
+
+	// now: n = bytes already written
+	int p = size - n;	// number of bytes to write
+	memcpy(&(lb->data[lb->write_ptr]), &(c[n]), p);
+	lb->write_ptr = (lb->write_ptr + p) % lb->size;
+}
+
+int sdlog2_logbuffer_get_ptr(struct sdlog2_logbuffer *lb, void **ptr)
+{
+	// bytes available to read
+	int available = lb->write_ptr - lb->read_ptr;
+
+	if (available == 0) {
+		return 0;	// buffer is empty
+	}
+
+	int n = 0;
+
+	if (available > 0) {
+		// read pointer is before write pointer, write all available bytes
+		n = available;
+
+	} else {
+		// read pointer is after write pointer, write bytes from read_ptr to end
+		n = lb->size - lb->read_ptr;
+	}
+
+	*ptr = &(lb->data[lb->read_ptr]);
+	return n;
+}
+
+void sdlog2_logbuffer_mark_read(struct sdlog2_logbuffer *lb, int n)
+{
+	lb->read_ptr = (lb->read_ptr + n) % lb->size;
+}
diff --git a/src/modules/sdlog2/sdlog2_ringbuffer.h b/src/modules/sdlog2/sdlog2_ringbuffer.h
new file mode 100644
index 000000000..287f56c34
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2_ringbuffer.h
@@ -0,0 +1,68 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sdlog2_ringbuffer.h
+ *
+ * Ring FIFO buffer for binary data.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#ifndef SDLOG2_RINGBUFFER_H_
+#define SDLOG2_RINGBUFFER_H_
+
+struct sdlog2_logbuffer {
+	// all pointers are in bytes
+	int write_ptr;
+	int read_ptr;
+	int size;
+	char *data;
+};
+
+void sdlog2_logbuffer_init(struct sdlog2_logbuffer *lb, int size);
+
+int sdlog2_logbuffer_free(struct sdlog2_logbuffer *lb);
+
+int sdlog2_logbuffer_count(struct sdlog2_logbuffer *lb);
+
+int sdlog2_logbuffer_is_empty(struct sdlog2_logbuffer *lb);
+
+void sdlog2_logbuffer_write(struct sdlog2_logbuffer *lb, void *ptr, int size);
+
+int sdlog2_logbuffer_get_ptr(struct sdlog2_logbuffer *lb, void **ptr);
+
+void sdlog2_logbuffer_mark_read(struct sdlog2_logbuffer *lb, int n);
+
+#endif