/*

    Serial download of track data from GPS loggers with Skytraq chipset.

    Copyright (C) 2008-2019  Mathias Adam, m.adam (at) adamis.de

    2008         J.C Haessig, jean-christophe.haessig (at) dianosis.org
    2009-09-06 | Josef Reisinger | Added "set target location", i.e. -i skytrag,targetlocation=<lat>:<lng>
    2010-10-23 | Josef Reisinger | Added read/write for miniHomer POI

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include "defs.h"
#include "gbser.h"
#include <QtCore/QThread>
#include <cmath>
#include <cstdio>
#include <cstdlib>

#define MYNAME "skytraq"

#define TIMEOUT			5000
#define SECTOR_SIZE		4096
#define FULL_ITEM_LEN		18
#define COMPACT_ITEM_LEN	8
#define MULTI_HZ_ITEM_LEN		20

/* Maximum number of chars to skip while waiting for a reply: */
#define RETRIES			250
/* Maximum number of messages to read while expecting a specific message or ACK/NACK: */
#define MSG_RETRIES		3
/* Abort when reading a specific sector fails this many times: */
#define SECTOR_RETRIES		3

#define res_OK			0
#define res_ERROR		-1
#define res_NACK		-2
#define res_PROTOCOL_ERR	-3
#define res_NOTFOUND		-4

#define MIN(X,Y) ((X) < (Y) ? (X) : (Y))
#define MAX(X,Y) ((X) > (Y) ? (X) : (Y))


static void* serial_handle = nullptr;		/* IO file descriptor */
static int skytraq_baud = 0;		/* detected baud rate */
static gbfile* file_handle = nullptr;		/* file descriptor (used by skytraq-bin format) */

static char* opt_erase = nullptr;		/* erase after read? (0/1) */
static char* opt_initbaud = nullptr;		/* baud rate used to init device */
static char* opt_dlbaud = nullptr;		/* baud rate used for downloading tracks */
static char* opt_read_at_once = nullptr;	/* number of sectors to read at once (Venus6 only) */
static char* opt_first_sector = nullptr;	/* first sector to be read from the device (default: 0) */
static char* opt_last_sector = nullptr;	/* last sector to be read from the device (default: smart read everything) */
static char* opt_dump_file = nullptr;		/* dump raw data to this file (optional) */
static char* opt_no_output = nullptr;		/* disable output? (0/1) */
static char* opt_set_location = nullptr;	/* set if the "targetlocation" options was used */
static char* opt_configure_logging = nullptr;
static char* opt_gps_utc_offset = nullptr;
static char* opt_gps_week_rollover = nullptr;

static
QVector<arglist_t> skytraq_args = {
  {
    "erase", &opt_erase, "Erase device data after download",
    "0", ARGTYPE_BOOL, ARG_NOMINMAX, nullptr
  },
  {
    "targetlocation", &opt_set_location, "Set location finder target location as lat,lng",
    nullptr, ARGTYPE_STRING, "", "", nullptr
  },
  {
    "configlog", &opt_configure_logging, "Configure logging parameter as tmin:tmax:dmin:dmax",
    nullptr, ARGTYPE_STRING, "", "", nullptr
  },
  {
    "baud", &opt_dlbaud, "Baud rate used for download",
    "230400", ARGTYPE_INT, "0", "230400", nullptr
  },
  {
    "initbaud", &opt_initbaud, "Baud rate used to init device (0=autodetect)",
    "0", ARGTYPE_INT, "4800", "230400", nullptr
  },
  {
    "read-at-once", &opt_read_at_once, "Number of sectors to read at once (0=use single sector mode)",
    "255", ARGTYPE_INT, "0", "255", nullptr
  },
  {
    "first-sector", &opt_first_sector, "First sector to be read from the device",
    "0", ARGTYPE_INT, "0", "65535", nullptr
  },
  {
    "last-sector", &opt_last_sector, "Last sector to be read from the device (-1: smart read everything)",
    "-1", ARGTYPE_INT, "-1", "65535", nullptr
  },
  {
    "dump-file", &opt_dump_file, "Dump raw data to this file",
    nullptr, ARGTYPE_OUTFILE, ARG_NOMINMAX, nullptr
  },
  {
    "no-output", &opt_no_output, "Disable output (useful with erase)",
    "0", ARGTYPE_BOOL, ARG_NOMINMAX, nullptr
  },
  {
    "gps-utc-offset", &opt_gps_utc_offset, "Seconds that GPS time tracks UTC (0: best guess)",
    "0", ARGTYPE_INT, ARG_NOMINMAX, nullptr
  },
  {
    "gps-week-rollover", &opt_gps_week_rollover, "GPS week rollover period we're in (-1: best guess)",
    "-1", ARGTYPE_INT, ARG_NOMINMAX, nullptr
  },
};

static
QVector<arglist_t> skytraq_fargs = {
  {
    "first-sector", &opt_first_sector, "First sector to be read from the file",
    "0", ARGTYPE_INT, "0", "65535", nullptr
  },
  {
    "last-sector", &opt_last_sector, "Last sector to be read from the file (-1: read till empty sector)",
    "-1", ARGTYPE_INT, "-1", "65535", nullptr
  },
  {
    "gps-utc-offset", &opt_gps_utc_offset, "Seconds that GPS time tracks UTC (0: best guess)",
    "0", ARGTYPE_INT, ARG_NOMINMAX, nullptr
  },
  {
    "gps-week-rollover", &opt_gps_week_rollover, "GPS week rollover period we're in (-1: best guess)",
    "-1", ARGTYPE_INT, ARG_NOMINMAX, nullptr
  },
};

static void
db(int l, const char* msg, ...)
{
  va_list ap;
  va_start(ap, msg);
  if (global_opts.debug_level >= l) {
    vprintf(msg, ap);
  }
  va_end(ap);
}

static void
rd_drain()
{
  if (gbser_flush(serial_handle)) {
    db(1, MYNAME ": rd_drain(): Comm error\n");
  }
}

static int
rd_char(int* errors)
{
  while (*errors > 0) {
    int c = gbser_readc_wait(serial_handle, TIMEOUT);
    if (c < 0) {
      db(1, MYNAME ": rd_char(): Got error: %d\n", c);
      (*errors)--;
    } else {
      db(4, "rd_char(): Got char: %02x '%c'\n", c, isprint(c) ? c : '.');
      return c;
    }
  }
  fatal(MYNAME ": Too many read errors on serial port\n");
  return -1;
}

static int
rd_buf(uint8_t* buf, int len)
{
  char dump[16*3+16+2];

  /* Allow TIMEOUT plus the time needed to actually receive the data bytes:
   * baudrate/10 bytes per second (8 data bits, start and stop bit)
   * TODO: use dlbaud if selected.
   */
  int timeout = TIMEOUT + len;//*1000/(skytraq_baud/10);
  /*TODO: timeout gets <0 e.g. when len~=250000 --> 32bit signed int is too small.
  	if (skytraq_baud > 0)  timeout = TIMEOUT + (long long int)len*1000*10/(long long int)skytraq_baud;
  printf("len=%i  skytraq_baud=%i  timeout=%i\n", len, skytraq_baud, timeout);*/
  int rc = gbser_read_wait(serial_handle, (void*)buf, len, timeout);
  if (rc < 0) {
    db(1, MYNAME ": rd_buf(): Read error (%d)\n", rc);
    return res_ERROR;
  } else if (rc < len) {
    db(1, MYNAME ": rd_buf(): Read timout\n");
    return res_ERROR;
  }

  if (global_opts.debug_level >= 4) {
    db(4, "rd_buf():  dump follows:\n");
    dump[sizeof(dump)-1] = 0;
    for (int i = 0; i < (len+15)/16*16; i++) {		// count to next 16-byte boundary
      if (i < len) {
        snprintf(&dump[(i%16)*3], 4, "%02x ", buf[i]);
        snprintf(&dump[3*16+1+(i%16)], 2, "%c", isprint(buf[i]) ? buf[i] : '.');
      } else {
        memset(&dump[(i%16)*3], ' ', 3);
        dump[3*16+1+(i%16)] = ' ';
      }
      if ((i+1)%16 == 0) {
        dump[16*3] = ' ';	// gets overwritten with 0 by snprintf
        db(4, "%s\n", dump);
      }
    }
  }

  return res_OK;
}

static int
rd_word()
{
  int errors = 5;		/* allow this many errors */
  int c;
  uint8_t buffer[2];

  c = rd_char(&errors);
  if (c < 0) {
    db(1, MYNAME ": rd_word(): Got error: %d\n", c);
    return -1;
  }
  buffer[0] = c;
  c = rd_char(&errors);
  if (c < 0) {
    db(1, MYNAME ": rd_word(): Got error: %d\n", c);
    return -1;
  }
  buffer[1] = c;
  /*	if (rd_buf(buffer, 2) != res_OK) {
  		db(1, MYNAME ": rd_word(): Read error\n");
  		return res_ERROR;
  	}*/

  return (buffer[0] << 8) | buffer[1];
}

static void
wr_char(int c)
{
  int rc;
  db(4, "Sending: %02x '%c'\n", (unsigned)c, isprint(c) ? c : '.');
  if (rc = gbser_writec(serial_handle, c), gbser_OK != rc) {
    fatal(MYNAME ": Write error (%d)\n", rc);
  }
}

static void
wr_buf(const unsigned char* str, int len)
{
  for (int i = 0; i < len; i++) {
    wr_char(str[i]);
  }
}

/*******************************************************************************
* %%%        SkyTraq protocol implementation                               %%% *
*******************************************************************************/

static uint8_t NL[2] = { 0x0D, 0x0A };
static uint8_t MSG_START[2] = { 0xA0, 0xA1 };
static uint8_t SECTOR_READ_END[13] = { 'E','N','D', 0, 'C','H','E','C','K','S','U','M','=' };

static int
skytraq_calc_checksum(const unsigned char* buf, int len)
{
  int cs = 0;
  for (int i = 0; i < len; i++) {
    cs ^= buf[i];
  }
  return cs;
}

static int
skytraq_rd_msg(void* payload, unsigned int len)
{
  int errors = 5;		// Allow this many receiver errors silently.
  unsigned int c, i, state;
  signed int rcv_len;		// Negative length is read error.

  for (i = 0, state = 0; i < RETRIES && state < sizeof(MSG_START); i++) {
    c = rd_char(&errors);
    if (c == MSG_START[state]) {
      state++;
    } else if (c == MSG_START[0]) {
      state = 1;
    } else {
      state = 0;
    }
  }
  if (state < sizeof(MSG_START)) {
    db(1, MYNAME ": Didn't get message start tag\n");
    return res_ERROR;
  }

  if ((rcv_len = rd_word()) < (signed int)len) {
    if (rcv_len >= 0) {	/* negative values indicate receive errors */
      db(1, MYNAME ": Received message too short (got %i bytes, expected %u)\n",
         rcv_len, len);
      return res_PROTOCOL_ERR;
    }
    return res_ERROR;
  }
  /* at this point, we have rcv_len >= len >= 0 */

  db(2, "Receiving message with %i bytes of payload (expected >=%u)\n", rcv_len, len);
  rd_buf((uint8_t*) payload, len);

  unsigned int calc_cs = skytraq_calc_checksum((const unsigned char*) payload, len);
  for (i = 0; i < rcv_len-len; i++) {
    c = rd_char(&errors);
    calc_cs ^= c;
  }

  unsigned int rcv_cs = rd_char(&errors);
  if (rcv_cs != calc_cs) {
    fatal(MYNAME ": Checksum error: got 0x%02x, expected 0x%02x\n", rcv_cs, calc_cs);
  }

  if (rd_word() != 0x0D0A) {
    fatal(MYNAME ": Didn't get message end tag (CR/LF)\n");
  }

  return res_OK;
}

static void
skytraq_wr_msg(const uint8_t* payload, int len)
{
  rd_drain();

  wr_buf(MSG_START, sizeof(MSG_START));
  wr_char((len>>8) & 0x0FF);
  wr_char(len & 0x0FF);
  wr_buf(payload, len);

  int cs = skytraq_calc_checksum(payload, len);
  wr_char(cs);
  wr_buf(NL, sizeof(NL));
}

static int
skytraq_expect_ack(uint8_t id)
{
  uint8_t ack_msg[2];
  //int rcv_len;

  for (int i = 0; i < MSG_RETRIES; i++) {
//		rcv_len = skytraq_rd_msg(ack_msg, sizeof(ack_msg));
//		if (rcv_len == sizeof(ack_msg)) {
    if (skytraq_rd_msg(ack_msg, sizeof(ack_msg)) == res_OK) {
      if (ack_msg[0] == 0x83) {
        if (ack_msg[1] == id) {
          db(3, "Got ACK (id=0x%02x)\n", id);
          return res_OK;
        } else if (ack_msg[1] == 0) {
          /* some (all?) devices first send an ACK with id==0, skip that */
          continue;
        } else {
          db(1, MYNAME ": Warning: Got unexpected ACK (id=0x%02x)\n", ack_msg[1]);
          continue;
        }
      } else if (ack_msg[0] == 0x84) {
        db(3, "Warning: Got NACK (id=0x%02x)\n", ack_msg[1]);
        return res_NACK;
      } else {
        db(3, "Warning: Got unexpected message (id=0x%02x), expected ACK (id=0x%02x)\n",
           ack_msg[0], id);
      }
    } else {
      /* payload too short or didn't receive a message at all
          -> caller should either resend request or give up.
      */
      break;
    }
  }

  return res_PROTOCOL_ERR;
}

static int
skytraq_expect_msg(uint8_t id, uint8_t* payload, int len)
{
  for (int i = 0; i < MSG_RETRIES; i++) {
    int rc = skytraq_rd_msg(payload, len);
    if (rc < 0) {
      return rc;
    }
    if (payload[0] == id) {
      return len;
    }
  }

  return res_PROTOCOL_ERR;
}

static int
skytraq_wr_msg_verify(const uint8_t* payload, int len)
{
  for (int i = 0; i < MSG_RETRIES; i++) {
    if (i > 0) {
      db(1, "resending msg (id=0x%02x)...\n", payload[0]);
    }
    skytraq_wr_msg(payload, len);
    int rc = skytraq_expect_ack(payload[0]);
    if (rc == res_OK  ||  rc == res_NACK) {
      return rc;
    }
    db(1, MYNAME ": Got neither ACK nor NACK, ");
  }
  db(1, "aborting (msg id was 0x%02x).\n", payload[0]);

  return res_ERROR;
}

static int
skytraq_system_restart()
{
  uint8_t MSG_SYSTEM_RESTART[15] =
  { 0x01, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

  db(2, "restart system\n");
  return skytraq_wr_msg_verify(MSG_SYSTEM_RESTART, sizeof(MSG_SYSTEM_RESTART));
}

static int
skytraq_set_baud(int baud)
{
  /* Note: according to AN0003_v3.pdf, attrib == 0x00 means write to SRAM only, however
   * it seems to write to flash too. The Windows software sends 0x02 so we do here too.
   */
  uint8_t MSG_CONFIGURE_SERIAL_PORT[4]
    = { 0x05, 0x00, 0x00, 0x02 };

  db(2, "Setting baud rate to %i\n", baud);

  switch (baud) {
  case 4800:
    MSG_CONFIGURE_SERIAL_PORT[2] = 0;
    break;
  case 9600:
    MSG_CONFIGURE_SERIAL_PORT[2] = 1;
    break;
  case 19200:
    MSG_CONFIGURE_SERIAL_PORT[2] = 2;
    break;
  case 38400:
    MSG_CONFIGURE_SERIAL_PORT[2] = 3;
    break;
  case 57600:
    MSG_CONFIGURE_SERIAL_PORT[2] = 4;
    break;
  case 115200:
    MSG_CONFIGURE_SERIAL_PORT[2] = 5;
    break;
  case 230400:
    MSG_CONFIGURE_SERIAL_PORT[2] = 6;
    break;
  default:
    fatal(MYNAME ": Unsupported baud rate: %ibd\n", baud);
  }

  int rc = skytraq_wr_msg_verify(MSG_CONFIGURE_SERIAL_PORT, sizeof(MSG_CONFIGURE_SERIAL_PORT));
  if (rc != res_OK) {
    db(2, "Warning: error setting skytraq device baud rate\n");
    return rc;
  }

  db(3, "Now setting UART baud rate to %i\n", baud);
  rd_drain();
  if (gbser_set_speed(serial_handle, baud) != gbser_OK) {
    db(2, "Warning: error setting uart baud rate\n");
    return res_ERROR;
  }

  QThread::usleep(50);		/* allow UART to settle. */

  return res_OK;
}

static int
skytraq_configure_logging()
{
  // an0008-1.4.14: logs if
  // (dt > tmin & dd >= dmin & v >= vmin) | dt > tmax | dd > dmax | v > vmax
  unsigned int tmin=6, tmax=3600, dmin=0, dmax=10000;
  static uint8_t MSG_LOG_CONFIGURE_CONTROL[] = {
    0x18,			// message_id
    0x00, 0x00, 0x0e, 0x10,	// max_time: was 0x0000ffff (big endian!)
    0x00, 0x00, 0x00, 0x06,	// min_time: was 0x00000005
    0x00, 0x00, 0x27, 0x10,	// max_distance: was 0x0000ffff
    0x00, 0x00, 0x00, 0x00,	// min_distance
    0x00, 0x00, 0xff, 0xff,	// max_speed
    0x00, 0x00, 0x00, 0x00,	// min_speed
    0x01,			// datalog_enable: NOTE: always ON
    0x00			// reserved
  };

  if (opt_configure_logging) {
    if (*opt_configure_logging) {
      unsigned int nn = sscanf(opt_configure_logging, "%u:%u:%u:%u", &tmin, &tmax, &dmin, &dmax);
      if (nn>3) {
        db(0, "Reconfiguring logging to: tmin=%u, tmax=%u, dmin=%u, dmax=%u\n", tmin, tmax, dmin, dmax);
        be_write32(MSG_LOG_CONFIGURE_CONTROL+5, tmin);
        be_write32(MSG_LOG_CONFIGURE_CONTROL+1, tmax);
        be_write32(MSG_LOG_CONFIGURE_CONTROL+13, dmin);
        be_write32(MSG_LOG_CONFIGURE_CONTROL+9, dmax);
      } else {
        db(1, MYNAME "Option usage: configlog=tmin:tmax:dmin:dmax");
        return -1;
      }
    }
  }

  return skytraq_wr_msg_verify(MSG_LOG_CONFIGURE_CONTROL, sizeof(MSG_LOG_CONFIGURE_CONTROL));
}

static int
skytraq_get_log_buffer_status(uint32_t* log_wr_ptr, uint16_t* sectors_free, uint16_t* sectors_total)
{
  uint8_t MSG_LOG_STATUS_CONTROL = 0x17;
  struct {
    uint8_t id[1];
    uint8_t log_wr_ptr[4];
    uint8_t sectors_free[2];
    uint8_t sectors_total[2];
    uint8_t max_time[4], min_time[4], max_dist[4], min_dist[4], max_speed[4], min_speed[4];
    uint8_t datalog_enable[1], log_fifo_mode[1];
  } MSG_LOG_STATUS_OUTPUT;
  unsigned int rc;

  if ((rc = skytraq_wr_msg_verify(&MSG_LOG_STATUS_CONTROL, 1)) != res_OK) {	/* get memory status */
    db(1, MYNAME ": Error sending LOG STATUS CONTROL message (%d)\n", rc);
    return res_ERROR;
  }

  rc = skytraq_expect_msg(0x94, (uint8_t*)&MSG_LOG_STATUS_OUTPUT, sizeof(MSG_LOG_STATUS_OUTPUT));
  if (rc < sizeof(MSG_LOG_STATUS_OUTPUT)) {
    db(1, MYNAME ": Didn't receive expected reply (%d)\n", rc);
    return res_ERROR;
  }

  *log_wr_ptr = le_readu32(&MSG_LOG_STATUS_OUTPUT.log_wr_ptr);
  *sectors_free = le_readu16(&MSG_LOG_STATUS_OUTPUT.sectors_free);
  *sectors_total = le_readu16(&MSG_LOG_STATUS_OUTPUT.sectors_total);

  // unsigned char log_bool, fifo_mode;
  char* mystatus;
  unsigned int tmax = le_readu32(&MSG_LOG_STATUS_OUTPUT.max_time);
  unsigned int tmin = le_readu32(&MSG_LOG_STATUS_OUTPUT.min_time);
  unsigned int dmax = le_readu32(&MSG_LOG_STATUS_OUTPUT.max_dist);
  unsigned int dmin = le_readu32(&MSG_LOG_STATUS_OUTPUT.min_dist);
  unsigned int vmax = le_readu32(&MSG_LOG_STATUS_OUTPUT.max_speed);
  unsigned int vmin = le_readu32(&MSG_LOG_STATUS_OUTPUT.min_speed);
  // log_bool = *(MSG_LOG_STATUS_OUTPUT.datalog_enable);
  // fifo_mode = *(MSG_LOG_STATUS_OUTPUT.log_fifo_mode);
  xasprintf(&mystatus, "#logging: tmin=%u, tmax=%u, dmin=%u, dmax=%u, vmin=%u, vmax=%u\n", tmin, tmax, dmin, dmax, vmin, vmax);
  db(1, mystatus);
  xfree(mystatus);

  return res_OK;
}

/* reads 32-bit "middle-endian" fields */
static unsigned int me_read32(const unsigned char* p)
{
  return ((unsigned)be_read16(p+2) << 16) | ((unsigned)be_read16(p));
}

static time_t
gpstime_to_timet(int week, int sec)
{
  /* Notes:
   *   * week rollover period can be specified using option
   *     gps-week-rollover, otherwise input timestamps are
   *     assumed to be within previous 1024 weeks from today
   *   * list of leap seconds taken from
   *     <http://maia.usno.navy.mil/ser7/tai-utc.dat>
   *     as of 2019-01-19. Please update when necessary.
   *     Announcement of leap seconds:
   *     <http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat>
   *   * leap seconds of 1999 JAN  1 and before are not reflected
   *     here, beware when using this for really old data
   *   * overflow of sec into next week is allowed
   *     (i.e. sec >= 7*24*3600 = 604800 is allowed)
   */
  time_t gps_timet = 315964800;     /* Jan 06 1980 0:00 UTC */

  int week_rollover = atoi(opt_gps_week_rollover);
  if (week_rollover < 0) {
    int current_week = (time(nullptr)-gps_timet)/(7*SECONDS_PER_DAY);
    week_rollover = current_week/1024 - (week > current_week%1024 ? 1 : 0);
  }
  gps_timet += (week+week_rollover*1024)*7*SECONDS_PER_DAY + sec;

  int override = atoi(opt_gps_utc_offset);
  if (override) {
    gps_timet -= override;
    return gps_timet;
  }

  /* leap second compensation: */
  gps_timet -= 13;  /* diff GPS-UTC=13s (valid from Jan 01 1999 on) */
  if (gps_timet >= 1136073600) {    /* Jan 01 2006 0:00 UTC */
    gps_timet--;                    /*   GPS-UTC = 14s      */
  }
  if (gps_timet >= 1230768000) {    /* Jan 01 2009 0:00 UTC */
    gps_timet--;                    /*   GPS-UTC = 15s      */
  }
  if (gps_timet >= 1341100800) {    /* Jul 01 2012 0:00 UTC */
    gps_timet--;                    /*   GPS-UTC = 16s      */
  }
  if (gps_timet >= 1435708800) {    /* Jul 01 2015 0:00 UTC */
    gps_timet--;                    /*   GPS-UTC = 17s      */
  }
  if (gps_timet >= 1483228800) {    /* Jan 01 2017 0:00 UTC */
    gps_timet--;                    /*   GPS-UTC = 18s      */
  }
  // Future: Consult http://maia.usno.navy.mil/ser7/tai-utc.dat
  // use http://www.stevegs.com/utils/jd_calc/ for Julian to UNIX sec

  return gps_timet;     /* returns UTC time */
}

static void
ECEF_to_LLA(double x, double y, long z, double* lat, double* lon, double* alt)
{
  /* constants: */
  const double CA   = 6378137.0;
  const double CB   = 6356752.31424518;
  const double CE2  = (CA*CA - CB*CB) / (CA*CA);    /* =e^2 */
  const double CE_2 = (CA*CA - CB*CB) / (CB*CB);    /* =e'^2 */

  /* auxiliary values: */
  double AP = sqrt(x*x + y*y);
  double ATHETA = atan2(z*CA, AP*CB);

  /* latitude (in radians): */
  *lat = atan2(z + CE_2 * CB * pow(sin(ATHETA), 3), AP - CE2 * CA * pow(cos(ATHETA), 3));

  /* longitude (in radians): */
  *lon = atan2(y, x);

  /* height above ellipsoid (in meters): */
  *alt = AP/cos(*lat) - CA/sqrt(1 - CE2 * pow(sin(*lat), 2));

  *lat = *lat /M_PI*180;
  *lon = *lon /M_PI*180;
}

struct read_state {
  route_head*          route_head_;
  unsigned            wpn, tpn;

  unsigned gps_week;
  unsigned gps_sec;
  long x, y, z;
};

static void
state_init(struct read_state* pst)
{
  auto* track = new route_head;
  track->rte_name = "SkyTraq tracklog";
  track->rte_desc = "SkyTraq GPS tracklog data";
  track_add_head(track);

  pst->route_head_ = track;
  pst->wpn        = 0;
  pst->tpn        = 0;

  pst->gps_week   = 0;
  pst->gps_sec    = 0;
  pst->x          = 0;
  pst->y          = 0;
  pst->z          = 0;
}

static Waypoint*
make_trackpoint(struct read_state* st, double lat, double lon, double alt)
{
  auto* wpt = new Waypoint;

  wpt->shortname = QString::asprintf("TP%04d", ++st->tpn);

  wpt->latitude       = lat;
  wpt->longitude      = lon;
  wpt->altitude       = alt;
  wpt->SetCreationTime(gpstime_to_timet(st->gps_week, st->gps_sec));

  return wpt;
}

struct full_item {
  uint32_t gps_week;
  uint32_t gps_sec;
  int32_t  x;
  int32_t  y;
  int32_t  z;
};

struct compact_item {
  uint16_t dt;
  int16_t dx;
  int16_t dy;
  int16_t dz;
};

struct multi_hz_item {
  uint32_t gps_week;
  uint32_t gps_sec;
  int32_t  lat;
  int32_t  lon;
  int32_t  alt;
};


struct full_item_frame {
  unsigned char ts[4];
  unsigned char x[4];
  unsigned char y[4];
  unsigned char z[4];
};

struct compact_item_frame {
  unsigned char dt[2]; /* big endian unsigned short */
  unsigned char dpos[4];
};

struct multi_hz_item_frame {
  unsigned char v_kmh[2];
  unsigned char ts[4];
  unsigned char lat[4];
  unsigned char lon[4];
  unsigned char alt[4];
};

struct item_frame {
  unsigned char type_and_speed[2];
  union {
    multi_hz_item_frame multi_hz;
    full_item_frame full;
    compact_item_frame comp;
  };
};
#define ITEM_WEEK_NUMBER(item) (item->type_and_speed[1] | ((item->type_and_speed[0] & 0x03) << 8))

#define POW_2_M20 0.000000953674316
#define POW_2_M7 0.0078125

#define ITEM_TYPE(item) (item->type_and_speed[0] >> 4)
#define ITEM_SPEED(item) (item->type_and_speed[1] | ((item->type_and_speed[0] & 0x0F) << 8))

static int
process_data_item(struct read_state* pst, const item_frame* pitem, int len)
{
  int res = 0;
  double lat;
  double lon;
  double alt;
  double spe;
  unsigned int ts;
  int poi = 0;
  full_item f;
  compact_item c;
  multi_hz_item m;
  Waypoint* tpt = nullptr;

  switch (ITEM_TYPE(pitem)) {

  case 0xc:	/* POI item (same structure as full) */
    poi = 1;
    /* fallthrough */

  case 0x2:	/* Multi HZ item */
    if (len < MULTI_HZ_ITEM_LEN) {
      db(1, MYNAME ": Not enough bytes in sector for a full item.\n");
      return res_ERROR;
    }
    m.gps_week = ITEM_WEEK_NUMBER(pitem);
    ts = me_read32(pitem->multi_hz.ts);
    m.gps_sec = ((int)(ts & 0x3FFFFFFF)) / 1000;
    m.lat = me_read32(pitem->multi_hz.lat);
    m.lon = me_read32(pitem->multi_hz.lon);
    m.alt = me_read32(pitem->multi_hz.alt);

    pst->gps_week = m.gps_week;
    pst->gps_sec = m.gps_sec;

    spe = KPH_TO_MPS(be_read16(pitem->multi_hz.v_kmh));

    db(4, "Got multi hz item: week=%i sec=%i lat=%i  lon=%i  alt=%i  speed=%f\n",
       m.gps_week, m.gps_sec,
       m.lat, m.lon, m.alt,
       spe);

    lat = m.lat * POW_2_M20;
    lon = m.lon * POW_2_M20;
    alt = m.alt * POW_2_M7;

    tpt = make_trackpoint(pst, lat, lon, alt);
    WAYPT_SET(tpt, speed, spe); /* convert speed to m/s */
    track_add_wpt(pst->route_head_, tpt);

    res = MULTI_HZ_ITEM_LEN;
    break;

  case 0x6:	/* POI item (same structure as full) */
    poi = 1;
    /* fallthrough */

  case 0x4:	/* full item */
    if (len < FULL_ITEM_LEN) {
      db(1, MYNAME ": Not enough bytes in sector for a full item.\n");
      return res_ERROR;
    }
    ts = me_read32(pitem->full.ts);
    f.gps_week = ts & 0x000003FF;
    f.gps_sec = ts >> 12;
    f.x = me_read32(pitem->full.x);
    f.y = me_read32(pitem->full.y);
    f.z = me_read32(pitem->full.z);

    pst->gps_week = f.gps_week;
    pst->gps_sec = f.gps_sec;
    pst->x = f.x;
    pst->y = f.y;
    pst->z = f.z;

    db(4, "Got %s item: week=%i  sec=%i  x=%i  y=%i  z=%i  speed=%i\n",
       poi ? "POI" : "full",
       f.gps_week, f.gps_sec,
       f.x, f.y, f.z,
       ITEM_SPEED(pitem));

    res = FULL_ITEM_LEN;
    break;

  case 0x8:	/* compact item */
    if (len < COMPACT_ITEM_LEN) {
      db(1, MYNAME ": Not enough bytes in sector for a compact item.\n");
      return res_ERROR;
    }
    c.dx = (pitem->comp.dpos[1] >> 6) | (pitem->comp.dpos[0] << 2);
    c.dy = (pitem->comp.dpos[1] & 0x3F) | ((pitem->comp.dpos[2] & 0xF0) << 2);
    c.dz = pitem->comp.dpos[3] | ((pitem->comp.dpos[2] & 0x03) << 8);
    if (c.dx > 511) {
      c.dx = 511-c.dx;  /* make proper signed values */
    }
    if (c.dy > 511) {
      c.dy = 511-c.dy;
    }
    if (c.dz > 511) {
      c.dz = 511-c.dz;
    }
    c.dt = (pitem->comp.dt[0] << 8) | pitem->comp.dt[1];

    db(4, "Got compact item: dt=%i  dx=%i  dy=%i  dz=%i  speed=%i uu=%i\n",
       c.dt, c.dx, c.dy, c.dz,
       ITEM_SPEED(pitem), (pitem->comp.dpos[2] & 0x0F)>>2);

    pst->gps_sec += c.dt;
    pst->x += c.dx;
    pst->y += c.dy;
    pst->z += c.dz;

    res = COMPACT_ITEM_LEN;
    break;

  default:
    db(1, MYNAME ": Unknown item type encountered: 0x%02x\n", ITEM_TYPE(pitem));
    return 0;
  }

  if (res == COMPACT_ITEM_LEN  ||  res == FULL_ITEM_LEN) {
    ECEF_to_LLA(pst->x, pst->y, pst->z, &lat, &lon, &alt);
//		GPS_Math_XYZ_To_WGS84LatLonH(&lat, &lon, &alt, pst->x, pst->y, pst->z);
    tpt = make_trackpoint(pst, lat, lon, alt);
    WAYPT_SET(tpt, speed, KPH_TO_MPS(ITEM_SPEED(pitem))); /* convert speed to m/s */

    if (poi) {
      waypt_add(new Waypoint(*tpt));
    }

    if (nullptr == pst->route_head_) {
      db(1, MYNAME ": New Track\n");
      pst->route_head_ = new route_head;
      track_add_head(pst->route_head_);
    }

    track_add_wpt(pst->route_head_, tpt);
  }

  return res;
}

static int	/* returns number of bytes processed (terminates on 0xFF i.e. empty or padding bytes) */
process_data_sector(struct read_state* pst, const uint8_t* buf, int len)
{
  int plen, ilen;

  for (plen = 0; plen < len  &&  buf[plen] != 0xFF; plen += ilen) {
    ilen = process_data_item(pst, (item_frame*)&buf[plen], len-plen);
    if (ilen <= 0) {
      fatal(MYNAME ": Error %i while processing data item #%i (starts at %i)\n",
            ilen, pst->tpn, plen);
    }
  }

  return plen;
}

/* Note: the buffer is being padded with 0xFFs if necessary so there are always SECTOR_SIZE valid bytes */
static int
skytraq_read_single_sector(unsigned int sector, uint8_t* buf)
{
  uint8_t MSG_LOG_SECTOR_READ_CONTROL[2] = { 0x1B, (uint8_t)(sector) };
  int errors = 5;		/* allow this many errors */
  unsigned int c, i, j, cs;
  uint8_t buffer[16];

  if (sector > 0xFF) {
    fatal(MYNAME ": Invalid sector number (%i)\n", sector);
  }

  db(2, "Reading sector #%i...\n", sector);

  if (skytraq_wr_msg_verify((uint8_t*)&MSG_LOG_SECTOR_READ_CONTROL, sizeof(MSG_LOG_SECTOR_READ_CONTROL)) != res_OK) {
    db(1, MYNAME ": Didn't receive ACK\n");
    return res_ERROR;
  }

#ifdef READ_SINGLE_CHARS
  for (i = 0, j = 0; i-j < SECTOR_SIZE && j < sizeof(SECTOR_READ_END); i++) {
    c = rd_char(&errors);
    buf[i] = c;
    if (c == SECTOR_READ_END[j]) {
      j++;
    } else if (c == SECTOR_READ_END[0]) {
      j = 1;
    } else {
      j = 0;
    }
  }
  if (j < sizeof(SECTOR_READ_END)) {
    db(1, MYNAME ": Didn't get sector end tag\n");
    return res_ERROR;
  }
  c = rd_char(&errors);	/* read checksum byte */
  buf[i] = c;
#else
  for (i = 0, j = 0; i-j < SECTOR_SIZE && j < sizeof(SECTOR_READ_END); i+=c) {
    rd_buf(buffer, 16);
    for (c = 0; c < 16 && j < sizeof(SECTOR_READ_END); c++) {
      buf[i+c] = buffer[c];
      if (buffer[c] == SECTOR_READ_END[j]) {
        j++;
      } else if (buffer[c] == SECTOR_READ_END[0]) {
        j = 1;
      } else {
        j = 0;
      }
    }
  }
  if (j < sizeof(SECTOR_READ_END)) {
    db(1, MYNAME ": Didn't get sector end tag\n");
    return res_ERROR;
  }
  if (c < 16) {
    buf[i] = buffer[c];
  } else {
    c = rd_char(&errors);	/* read checksum byte */
    buf[i] = c;
  }
#endif
  i = i-j;
  db(3, "Received %i bytes of log data\n", i);

//#define SINGLE_READ_WORKAROUND
#ifdef SINGLE_READ_WORKAROUND
  gbser_set_speed(serial_handle, skytraq_baud);
  rd_char(&errors);
  rd_char(&errors);
  rd_char(&errors);
  rd_char(&errors);
  rd_char(&errors);
  rd_char(&errors);
  skytraq_set_baud(atoi(opt_dlbaud));
#endif

  cs = skytraq_calc_checksum(buf, i);
  if (cs != buf[i+sizeof(SECTOR_READ_END)]) {
    db(1, MYNAME ": Checksum error while reading sector: got 0x%02x, expected 0x%02x\n",
       buf[i+sizeof(SECTOR_READ_END)], cs);
    return res_ERROR;
  }

  for (; i < SECTOR_SIZE; i++) {
    buf[i] = 0xFF;
  }

  return res_OK;
}

static int
skytraq_read_multiple_sectors(int first_sector, unsigned int sector_count, uint8_t* buf)
{
  uint8_t MSG_LOG_READ_MULTI_SECTORS[5] = { 0x1D };
  unsigned int i;

  if (first_sector < 0  ||  first_sector > 0xFFFF) {
    fatal(MYNAME ": Invalid sector number (%i)\n", first_sector);
  }
  be_write16(&MSG_LOG_READ_MULTI_SECTORS[1], first_sector);
  if (sector_count > 0xFFFF) {
    fatal(MYNAME ": Invalid sector count (%i)\n", sector_count);
  }
  be_write16(&MSG_LOG_READ_MULTI_SECTORS[3], sector_count);

  db(2, "Reading %i sectors beginning from #%i...\n", sector_count, first_sector);

  unsigned int read_result = skytraq_wr_msg_verify((uint8_t*)&MSG_LOG_READ_MULTI_SECTORS, sizeof(MSG_LOG_READ_MULTI_SECTORS));
  if (read_result != res_OK) {
    return read_result;
  }

  for (i = 0; i < sector_count; i++) {
    db(2, "Receiving data of sector #%i...\n", first_sector+i);
    rd_buf(buf+i*SECTOR_SIZE, SECTOR_SIZE);
  }
  rd_buf(buf+SECTOR_SIZE*sector_count, sizeof(SECTOR_READ_END)+6);

  uint8_t* buf_end_tag = buf + SECTOR_SIZE*sector_count;
  for (i = 0; i < sizeof(SECTOR_READ_END); i++) {
    if (buf_end_tag[i] != SECTOR_READ_END[i]) {
      db(1, MYNAME ": Wrong end tag: got 0x%02x ('%c'), expected 0x%02x ('%c')\n",
         buf_end_tag[i], isprint(buf_end_tag[i]) ? buf_end_tag[i] : '.',
         SECTOR_READ_END[i], isprint(SECTOR_READ_END[i]) ? SECTOR_READ_END[i] : '.');
      return res_ERROR;
    }
  }

  unsigned int cs = skytraq_calc_checksum(buf, SECTOR_SIZE*sector_count);
  if (cs != buf_end_tag[sizeof(SECTOR_READ_END)]) {
    db(1, MYNAME ": Checksum error while reading sector: got 0x%02x, expected 0x%02x\n",
       buf_end_tag[sizeof(SECTOR_READ_END)], cs);
    return res_ERROR;
  }

  return res_OK;
}

static void
skytraq_read_tracks()
{
  struct read_state st;
  uint32_t log_wr_ptr;
  uint16_t sectors_free, sectors_total, /*sectors_used_a, sectors_used_b,*/ sectors_used;
  int t, rc, got_sectors, total_sectors_read = 0;
  int read_at_once = MAX(atoi(opt_read_at_once), 1);
  int opt_first_sector_val = atoi(opt_first_sector);
  int opt_last_sector_val = atoi(opt_last_sector);
  int multi_read_supported = 1;
  gbfile* dumpfile = nullptr;

  state_init(&st);

  if (skytraq_get_log_buffer_status(&log_wr_ptr, &sectors_free, &sectors_total) != res_OK) {
    fatal(MYNAME ": Can't get log buffer status\n");
  }

  db(1, MYNAME ": Device status: free sectors: %i / total sectors: %i / %i%% used / write ptr: %i\n",
     sectors_free, sectors_total, 100 - sectors_free*100 / sectors_total, log_wr_ptr);

  if (opt_first_sector_val >= sectors_total) {
    db(1, "Warning: sector# specified by option first-sector (%i) is beyond reported total sector count (%i)",
       opt_first_sector_val, sectors_total);
  }
  /* Workaround: sectors_free is sometimes reported wrong. Tried to use log_wr_ptr as an
     indicator for how many sectors are currently used. However this isn't correct in every case too.
     The current read logic is aware of that so this shouldn't be necessary anymore.
  	sectors_used_a = sectors_total - sectors_free;
  	sectors_used_b = (log_wr_ptr + SECTOR_SIZE - 1) / SECTOR_SIZE;
  	if (sectors_used_a != sectors_used_b) {
  		db(1, "Warning: device reported inconsistent number of used sectors (a=%i, b=%i), "\
  		   "using max=%i\n", sectors_used_a, sectors_used_b, MAX(sectors_used_a, sectors_used_b));
  	}
  	sectors_used = MAX(sectors_used_a, sectors_used_b);
  */
  if (opt_last_sector_val < 0) {
    sectors_used = sectors_total - sectors_free + 1 /*+5*/;
    if (opt_first_sector_val >= sectors_used) {
      sectors_used = opt_first_sector_val + 1;
    }
  } else {
    sectors_used = opt_last_sector_val;
    if (opt_last_sector_val >= sectors_total) {
      db(1, "Warning: sector# specified by option last-sector (%i) is beyond reported total sector count (%i)",
         opt_last_sector_val, sectors_total);
    }
  }

  auto* buffer = (uint8_t*) xmalloc(SECTOR_SIZE*read_at_once+sizeof(SECTOR_READ_END)+6);
  // m.ad/090930: removed code that tried reducing read_at_once if necessary since doesn't work with xmalloc

  if (opt_dump_file) {
    dumpfile = gbfopen(opt_dump_file, "w", MYNAME);
  }

  db(1, MYNAME ": Reading log data from device...\n");
  db(1, MYNAME ": start=%d used=%d\n", opt_first_sector_val, sectors_used);
  db(1, MYNAME ": opt_last_sector_val=%d\n", opt_last_sector_val);
  for (int i = opt_first_sector_val; i < sectors_used; i += got_sectors) {
    for (t = 0, got_sectors = 0; (t < SECTOR_RETRIES) && (got_sectors <= 0); t++) {
      if (atoi(opt_read_at_once) == 0  ||  multi_read_supported == 0) {
        rc = skytraq_read_single_sector(i, buffer);
        if (rc == res_OK) {
          got_sectors = 1;
        }
      } else {
        /* Try to read read_at_once sectors at once.
         * If tere aren't any so many interesting ones, read the remainder (sectors_used-i).
         * And read at least 1 sector.
         */
        read_at_once = MAX(MIN(read_at_once, sectors_used-i), 1);

        rc = skytraq_read_multiple_sectors(i, read_at_once, buffer);
        switch (rc) {
        case res_OK:
          got_sectors = read_at_once;
          read_at_once = MIN(read_at_once*2, atoi(opt_read_at_once));
          break;

        case res_NACK:
          db(1, MYNAME ": Device doesn't seem to support reading multiple "
             "sectors at once, falling back to single read.\n");
          multi_read_supported = 0;
          break;

        default:
          /* On failure, try with less sectors */
          read_at_once = MAX(read_at_once/2, 1);
        }
      }
    }
    if (got_sectors <= 0) {
      fatal(MYNAME ": Error reading sector %i\n", i);
    }

    total_sectors_read += got_sectors;

    if (dumpfile) {
      gbfwrite(buffer, SECTOR_SIZE, got_sectors, dumpfile);
    }

    if (*opt_no_output == '1') {
      continue;		// skip decoding
    }

    for (int s = 0; s < got_sectors; s++) {
      db(4, MYNAME ": Decoding sector #%i...\n", i+s);
      rc = process_data_sector(&st, buffer+s*SECTOR_SIZE, SECTOR_SIZE);
      if (rc == 0) {
        db(1, MYNAME ": Empty sector encountered: apparently only %i sectors are "
           "used but device reported %i.\n",
           i+s, sectors_used);
        i = sectors_used;	/* terminate to avoid reading stale data still in the logger */
        break;
      } else if (rc >= (4096-FULL_ITEM_LEN) && i+s+1 >= sectors_used && i+s+1 < sectors_total) {
        db(1, MYNAME ": Last sector is nearly full, reading one more sector\n");
        sectors_used++;
      }
    }
  }
  free(buffer);
  db(1, MYNAME ": Got %i trackpoints from %i sectors.\n", st.tpn, total_sectors_read);

  if (dumpfile) {
    gbfclose(dumpfile);
  }
}

static int
skytraq_probe()
{
  int baud_rates[] = { 9600, 230400, 115200, 57600, 4800, 19200, 38400 };
  int baud_rates_count = sizeof(baud_rates)/sizeof(baud_rates[0]);
  int initbaud = atoi(opt_initbaud);
  uint8_t MSG_QUERY_SOFTWARE_VERSION[2] = { 0x02, 0x01 };
  struct {
    uint8_t id;
    uint8_t sw_type;
    uint8_t kernel_ver[4];
    uint8_t odm_ver[4];
    uint8_t revision[4];
  } MSG_SOFTWARE_VERSION;
  int rc;

  // TODO: get current serial port baud rate and try that first
  // (only sensible if init to 4800 can be disabled...)

  if (initbaud > 0) {
    baud_rates[0] = initbaud;
    baud_rates_count = 1;
  }

  for (int i = 0; i < baud_rates_count; i++) {
    db(1, MYNAME ": Probing SkyTraq Venus at %ibaud...\n", baud_rates[i]);

    rd_drain();
    if ((rc = gbser_set_speed(serial_handle, baud_rates[i])) != gbser_OK) {
      db(1, MYNAME ": Set baud rate to %d failed (%d), retrying...\n", baud_rates[i], rc);
      if ((rc = gbser_set_speed(serial_handle, baud_rates[i])) != gbser_OK) {
        db(1, MYNAME ": Set baud rate to %d failed (%d)\n", baud_rates[i], rc);
        continue;
      }
    }

    QThread::usleep(50);		/* allow UART to settle. */

    skytraq_wr_msg(MSG_QUERY_SOFTWARE_VERSION,	/* get firmware version */
                   sizeof(MSG_QUERY_SOFTWARE_VERSION));
    if ((rc = skytraq_expect_ack(0x02)) != res_OK) {
      db(2, "Didn't receive ACK (%d), retrying...\n", rc);
      skytraq_wr_msg(MSG_QUERY_SOFTWARE_VERSION,	/* get firmware version */
                     sizeof(MSG_QUERY_SOFTWARE_VERSION));
      if ((rc = skytraq_expect_ack(0x02)) != res_OK) {
        db(2, "Didn't receive ACK (%d)\n", rc);
        continue;
      }
    }
    /*		note: _verify retries on errors, probe takes too long.
    		if (skytraq_wr_msg_verify(MSG_QUERY_SOFTWARE_VERSION,
    			sizeof(MSG_QUERY_SOFTWARE_VERSION)) != res_OK)
    		{
    			continue;
    		}*/
    rc = skytraq_expect_msg(0x80, (uint8_t*)&MSG_SOFTWARE_VERSION, sizeof(MSG_SOFTWARE_VERSION));
    if (rc < (int)sizeof(MSG_SOFTWARE_VERSION)) {
      db(2, "Didn't receive expected reply (%d)\n", rc);
    } else {
      db(1, MYNAME ": Venus device found: Kernel version = %i.%i.%i, ODM version = %i.%i.%i, "\
         "revision (Y/M/D) = %02i/%02i/%02i\n",
         MSG_SOFTWARE_VERSION.kernel_ver[1], MSG_SOFTWARE_VERSION.kernel_ver[2],
         MSG_SOFTWARE_VERSION.kernel_ver[3],
         MSG_SOFTWARE_VERSION.odm_ver[1], MSG_SOFTWARE_VERSION.odm_ver[2],
         MSG_SOFTWARE_VERSION.odm_ver[3],
         MSG_SOFTWARE_VERSION.revision[1], MSG_SOFTWARE_VERSION.revision[2],
         MSG_SOFTWARE_VERSION.revision[3]);

      return baud_rates[i];
    }
  }

  return res_NOTFOUND;
}

static int
skytraq_erase()
{
  uint8_t MSG_LOG_ERASE = 0x19;

  db(1, MYNAME ": Erasing logger memory...\n");
  if (skytraq_wr_msg_verify(&MSG_LOG_ERASE, sizeof(MSG_LOG_ERASE)) != res_OK) {
    db(1, MYNAME ": Didn't receive ACK\n");
    return res_ERROR;
  }

  return res_OK;
}

static void
skytraq_set_location()
{
  double lat, lng;
  uint8_t MSG_SET_LOCATION[17] = { 0x36, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
  uint8_t MSG_GET_LOCATION = 0x35;

  db(3, MYNAME ": set_location='%s'\n", opt_set_location);

  sscanf(opt_set_location, "%lf:%lf", &lat, &lng);
  le_write_double(&MSG_SET_LOCATION[1], lat);
  le_write_double(&MSG_SET_LOCATION[9], lng);
  for (unsigned char i : MSG_SET_LOCATION) {
    db(3, "%02x ", i);
  }
  db(3, "\n");
  if (skytraq_wr_msg_verify((uint8_t*)&MSG_SET_LOCATION, sizeof(MSG_SET_LOCATION)) != res_OK) {
    fatal(MYNAME ": cannot set new location\n");
  }
  {
    char buf[32];
    skytraq_wr_msg_verify(&MSG_GET_LOCATION, 1);
    skytraq_rd_msg(buf, 32);
  }
}

/*******************************************************************************
* %%%        global callbacks called by gpsbabel main process              %%% *
*******************************************************************************/

static void
skytraq_rd_init(const QString& fname)
{
  if ((serial_handle = gbser_init(qPrintable(fname))) == nullptr) {
    fatal(MYNAME ": Can't open port '%s'\n", qPrintable(fname));
  }
  if ((skytraq_baud = skytraq_probe()) <= 0) {
    fatal(MYNAME ": Can't find skytraq device on '%s'\n", qPrintable(fname));
  }
}

static void
skytraq_rd_deinit()
{
  gbser_deinit(serial_handle);
  serial_handle = nullptr;
}

static void
skytraq_read()
{
  if (opt_set_location) {
    skytraq_set_location();
    return;
  }

  if (opt_configure_logging) {
    skytraq_configure_logging();
    return;
  }

  int dlbaud = atoi(opt_dlbaud);
  if (dlbaud != 0  &&  dlbaud != skytraq_baud) {
    skytraq_set_baud(dlbaud);
  }

  // read device unless no-output=1 and dump-file=0 (i.e. no data needed at all)
  if (*opt_no_output == '0'  ||  opt_dump_file != nullptr) {
    skytraq_read_tracks();
  }

  if (*opt_erase == '1') {
    skytraq_erase();
  }

  if (dlbaud != 0  &&  dlbaud != skytraq_baud) {
    skytraq_set_baud(skytraq_baud);		// note that _system_restart resets baud rate anyway...
  }
  skytraq_system_restart();
}

static void
file_init(const QString& fname)
{
  db(1, "Opening file...\n");
  if ((file_handle = gbfopen(fname, "rb", MYNAME)) == nullptr) {
    fatal(MYNAME ": Can't open file '%s'\n", qPrintable(fname));
  }
}

static void
file_deinit()
{
  db(1, "Closing file...\n");
  gbfclose(file_handle);
  file_handle = nullptr;
}

static void
file_read()
{
  struct read_state st;
  int got_bytes;
  int opt_first_sector_val = atoi(opt_first_sector);
  int opt_last_sector_val = atoi(opt_last_sector);

  state_init(&st);
  auto* buffer = (uint8_t*) xmalloc(SECTOR_SIZE);

  if (opt_first_sector_val > 0) {
    db(4, MYNAME ": Seeking to first-sector index %i\n", opt_first_sector_val*SECTOR_SIZE);
    gbfseek(file_handle, opt_first_sector_val*SECTOR_SIZE, SEEK_SET);
  }

  db(1, MYNAME ": Reading log data from file...\n");
  int sectors_read = 0;
  while ((got_bytes = gbfread(buffer, 1, SECTOR_SIZE, file_handle)) > 0) {
    db(4, MYNAME ": Decoding sector #%i...\n", sectors_read++);
    int rc = process_data_sector(&st, buffer, got_bytes);
    if (opt_last_sector_val < 0) {
      if (rc < (4096-FULL_ITEM_LEN)) {
        db(1, MYNAME ": Empty sector encountered, terminating.\n");
        break;
      }
    } else if (sectors_read-1 >= opt_last_sector_val) {
      db(1, MYNAME ": desired last-sector #%i reached, terminating.\n", sectors_read-1);
      break;
    }
  }
  xfree(buffer);
  db(1, MYNAME ": Got %i trackpoints from %i sectors.\n", st.tpn, sectors_read);
}

/**************************************************************************/

// capabilities below means: we can only read tracks

ff_vecs_t skytraq_vecs = {
  ff_type_serial,
  {
    ff_cap_read			/* waypoints */,
    ff_cap_read 			/* tracks */,
    ff_cap_none 			/* routes */
  },
  skytraq_rd_init,
  nullptr,
  skytraq_rd_deinit,
  nullptr,
  skytraq_read,
  nullptr,
  nullptr,
  &skytraq_args,
  CET_CHARSET_UTF8, 1         /* master process: don't convert anything */
 , NULL_POS_OPS,
 nullptr
};

ff_vecs_t skytraq_fvecs = {
  ff_type_file,
  {
    ff_cap_read			/* waypoints */,
    ff_cap_read 			/* tracks */,
    ff_cap_none 			/* routes */
  },
  file_init,
  nullptr,
  file_deinit,
  nullptr,
  file_read,
  nullptr,
  nullptr,
  &skytraq_fargs,
  CET_CHARSET_UTF8, 1         /* master process: don't convert anything */
 , NULL_POS_OPS,
 nullptr
};
/**************************************************************************/
/*
 * support POI of skytraq based miniHomer device
 * http://navin.com.tw/miniHomer.htm
 * 2010-10-23	Josef Reisinger
 */
#ifdef MYNAME
#undef MYNAME
#endif
#define MYNAME "miniHomer"
static char* opt_set_poi_home = nullptr;	/* set if a "poi" option was used */
static char* opt_set_poi_car = nullptr;	/* set if a "poi" option was used */
static char* opt_set_poi_boat = nullptr;	/* set if a "poi" option was used */
static char* opt_set_poi_heart = nullptr;	/* set if a "poi" option was used */
static char* opt_set_poi_bar = nullptr;	/* set if a "poi" option was used */
static QVector<arglist_t> miniHomer_args = {
  { "baud",         &opt_dlbaud,        "Baud rate used for download", "115200", ARGTYPE_INT, "0", "115200", nullptr },
  { "dump-file",    &opt_dump_file,     "Dump raw data to this file", nullptr, ARGTYPE_OUTFILE, ARG_NOMINMAX, nullptr },
  { "erase",        &opt_erase,         "Erase device data after download", "0", ARGTYPE_BOOL, ARG_NOMINMAX, nullptr },
  { "first-sector", &opt_first_sector,  "First sector to be read from the device", "0", ARGTYPE_INT, "0", "65535", nullptr },
  { "initbaud",     &opt_initbaud,      "Baud rate used to init device (0=autodetect)", "38400", ARGTYPE_INT, "38400", "38400", nullptr },
  { "last-sector",  &opt_last_sector,   "Last sector to be read from the device (-1: smart read everything)", "-1", ARGTYPE_INT, "-1", "65535", nullptr },
  { "no-output",    &opt_no_output,     "Disable output (useful with erase)", "0", ARGTYPE_BOOL, ARG_NOMINMAX, nullptr },
  { "read-at-once", &opt_read_at_once,  "Number of sectors to read at once (0=use single sector mode)", "255", ARGTYPE_INT, "0", "255", nullptr },
  { "Home",         &opt_set_poi_home,  "POI for Home Symbol as lat:lng[:alt]", nullptr, ARGTYPE_STRING, "", "", nullptr },
  { "Car",          &opt_set_poi_car,   "POI for Car Symbol as lat:lng[:alt]", nullptr, ARGTYPE_STRING, "", "", nullptr },
  { "Boat",         &opt_set_poi_boat,  "POI for Boat Symbol as lat:lng[:alt]", nullptr, ARGTYPE_STRING, "", "", nullptr },
  { "Heart",        &opt_set_poi_heart, "POI for Heart Symbol as lat:lng[:alt]", nullptr, ARGTYPE_STRING, "", "", nullptr },
  { "Bar",          &opt_set_poi_bar,   "POI for Bar Symbol as lat:lng[:alt]", nullptr, ARGTYPE_STRING, "", "", nullptr },
  {
    "gps-utc-offset", &opt_gps_utc_offset, "Seconds that GPS time tracks UTC (0: best guess)",
    "0", ARGTYPE_INT, ARG_NOMINMAX, nullptr
  },
  {
    "gps-week-rollover", &opt_gps_week_rollover, "GPS week rollover period we're in (-1: best guess)",
    "-1", ARGTYPE_INT, ARG_NOMINMAX, nullptr
  },
};
/*
 * Names of the POIs on miniHomer
 */
static const char* poinames[] = {
  "Home", "Car", "Boat", "Heart", "Bar"
};
#define NUMPOI (sizeof poinames/sizeof poinames[0])
#ifdef DEAD_CODE_IS_REBORN
static int getPoiByName(char* name)
{
  unsigned int i;
  for (i=0; i<NUMPOI; i++) {
    if (strcmp(poinames[i], name) == 0) {
      return i;
    }
  }
  return -1;
}
#endif
// Convert lla (lat, lng, alt) to ECEF
// Algorithm taken from these sources:
// http://www.mathworks.com/matlabcentral/fileexchange/7942-covert-lat-lon-alt-to-ecef-cartesian
// http://en.wikipedia.org/wiki/Geodetic_system#From_ECEF_to_geodetic
// http://earth-info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf
static void lla2ecef(double lat, double lng, double alt, double* ecef_x, double* ecef_y, double* ecef_z)
{
  long double a = 6378137.0;
  long double esqr = 6.69437999014e-3;

  long double llat = lat*M_PI/180;
  long double llng = lng*M_PI/180;
  long double lalt = alt;

  long double s = sin(llat);
  long double n = a / sqrt(1 - esqr * s*s);

  *ecef_x = (double)((n+lalt) * cos(llat) * cos(llng));
  *ecef_y = (double)((n+lalt) * cos(llat) * sin(llng));
  *ecef_z = (double)((n*(1-esqr) + lalt)* sin(llat));
}
static void miniHomer_get_poi()
{
  uint8_t MSG_GET_POI[3] = { 0x4D, 0, 0};
  uint8_t buf[32];
  double lat, lng, alt;

  for (unsigned int poi = 0; poi<NUMPOI; poi++) {
    MSG_GET_POI[1]=(poi>>8)&0xff;
    MSG_GET_POI[2]=(poi)&0xff;
    if (skytraq_wr_msg_verify((uint8_t*)&MSG_GET_POI, sizeof(MSG_GET_POI)) != res_OK) {
      warning(MYNAME ": cannot read poi %d '%s'\n", poi, poinames[poi]);
    }
    skytraq_rd_msg(buf, 25);
    double ecef_x = be_read_double(buf+1);
    double ecef_y = be_read_double(buf+9);
    double ecef_z = be_read_double(buf+17);

    // todo - how to determine not-set POIs ?
    if (ecef_x < 100.0 && ecef_y < 100.0 && ecef_z < 100.0) {
      db(2, MYNAME" : skipped poi %d for X=%f, y=%f, Z=%f\n", ecef_x, ecef_y, ecef_z);
    } else {
      ECEF_to_LLA(ecef_x, ecef_y, ecef_z, &lat, &lng, &alt);

      auto* wpt = new Waypoint;
      wpt->shortname      = QString::asprintf("POI_%s", poinames[poi]);
      wpt->description    = QString::asprintf("miniHomer points to this coordinates if the %s symbol is on", poinames[poi]);
      wpt->latitude       = lat;
      wpt->longitude      = lng;
      wpt->altitude       = alt;
      waypt_add(wpt);
      db(1, MYNAME ": got POI[%s]='%f %f %f/%f %f %f'\n", poinames[poi], lat, lng, alt, ecef_x, ecef_y, ecef_z);
    }
  }
}
/*
 * set lla (lat/lng/alt) specified as <lat>:<lng>[:<alt] for a given poi [0..4] in miniHomer
 * returns
 * 1  if poi was set
 * 0  if opt_poi was not set
 * -1 in case of errors
 *  the number of the POI will not be checked - if it is not correct, miniHome will send NACK
 */
static int miniHomer_set_poi(uint16_t poinum, const char* opt_poi)
{
#define MSG_SET_POI_SIZE (sizeof(uint8_t)+sizeof(uint16_t)+3*sizeof(double)+sizeof(uint8_t))
  uint8_t MSG_SET_POI[MSG_SET_POI_SIZE] = {
    0x4C, 0,  0, 		// cmd + poi (u16)
    0, 0, 0, 0, 0, 0, 0, 0,	//lat (double ecef)
    0, 0, 0, 0, 0, 0, 0, 0,	//lng (double ecef)
    0, 0, 0, 0, 0, 0, 0, 0,	//alt (double ecef)
    0 			// attr (u8, 1-> to flash, 0->ro sram)
  };
  double lat, lng, alt;
  double ecef_x, ecef_y, ecef_z;


  int result = 0;		// result will be 0 if opt_poi isn't set
  if (opt_poi) { 	// first check opt_poi
    if (*opt_poi) {
      lat=lng=alt=0.0;
      /*
       * parse format of <lat>:<lng>[:alt]
       * we assume at least two elements in the value string
       */
      int n = sscanf(opt_poi, "%lf:%lf:%lf", &lat, &lng, &alt);
      if (n >= 2) {
        db(3, "found %d elems '%s':poi=%s@%d, lat=%f, lng=%f, alt=%f over=%s\n", n, opt_poi, poinames[poinum], poinum, lat, lng, alt);
        lla2ecef(lat, lng, alt, &ecef_x, &ecef_y, &ecef_z);
        db(1, MYNAME ": set POI[%s]='%f %f %f/%f %f %f'\n", poinames[poinum], lat, lng, alt, ecef_x, ecef_y, ecef_z);
        be_write16(MSG_SET_POI+1, poinum);
        be_write_double(MSG_SET_POI+3, ecef_x);
        be_write_double(MSG_SET_POI+11, ecef_y);
        be_write_double(MSG_SET_POI+19, ecef_z);
        MSG_SET_POI[27]=0;
        if (skytraq_wr_msg_verify((uint8_t*)&MSG_SET_POI, sizeof(MSG_SET_POI)) == res_OK) {
          result=1;
        } else {
          warning(MYNAME ": cannot set poi %d '%s'\n", poinum, poinames[poinum]);
          result=-1;
        }
      } else {
        warning(MYNAME ": argument to %s needs to be like <lat>:<lng>[:<alt>]\n", poinames[poinum]);
        result=-1;
      }
    }
  }
  return result;
}
static QString mhport;
static void
miniHomer_rd_init(const QString& fname)
{
  opt_set_location=nullptr;	// otherwise it will lead to bus error
  skytraq_rd_init(fname);	// sets global var serial_handle
  mhport=fname;
}
static void
miniHomer_rd_deinit()
{
  skytraq_rd_deinit();
  mhport.clear();
}
#define SETPOI(poinum, poiname) if (opt_set_poi_##poiname )  {miniHomer_set_poi(poinum, opt_set_poi_##poiname);}
static void
miniHomer_read()
{
  int npoi=0;
  /*
   * read tracks and POI from miniHomer
   */
  if (miniHomer_set_poi(0, opt_set_poi_home) > 0) {
    npoi++;
  }
  if (miniHomer_set_poi(1, opt_set_poi_car) > 0) {
    npoi++;
  }
  if (miniHomer_set_poi(2, opt_set_poi_boat) > 0) {
    npoi++;
  }
  if (miniHomer_set_poi(3, opt_set_poi_heart) > 0) {
    npoi++;
  }
  if (miniHomer_set_poi(4, opt_set_poi_bar) > 0) {
    npoi++;
  }
  if (npoi == 0) {				// do not read if POIs are set (consider set & read distinct operations)
    skytraq_read();				// first read tracks (if not suppressed by cmd line params)
    // we need this call it initialized waypoint list etc...
    skytraq_rd_deinit(); 		// skytraq_read called system_reset, which changes the baud rate.

    skytraq_rd_init(mhport);    // Lets start from scratch and re-init the port
    miniHomer_get_poi();		// add POI as waypoints to the waypoints of the track
  }
}

ff_vecs_t miniHomer_vecs = {
  ff_type_serial,
  {
    ff_cap_read			/* waypoints */,
    ff_cap_read 			/* tracks */,
    ff_cap_none 			/* routes */
  },
  miniHomer_rd_init,
  nullptr,
  miniHomer_rd_deinit,
  nullptr,
  miniHomer_read,
  nullptr,
  nullptr,
  &miniHomer_args,
  CET_CHARSET_UTF8, 1,         /* master process: don't convert anything */
  NULL_POS_OPS,
  nullptr
};
