+/*
+ * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
+ */
+
+#define _BSD_SOURCE
+#define _XOPEN_SOURCE
+#include <time.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+
+#include <fcntl.h>
+#include <time.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <string.h>
+#include <termios.h>
+
+#include <libubox/utils.h>
+
+#include "log.h"
+#include "nmea.h"
+
+#define MAX_NMEA_PARAM 20
+#define MAX_TIME_OFFSET 2
+#define MAX_BAD_TIME 3
+
+struct nmea_param {
+ char *str;
+ int num;
+} nmea_params[MAX_NMEA_PARAM];
+
+static int nmea_bad_time;
+char longitude[32] = { 0 }, lattitude[32] = { 0 }, course[16] = { 0 }, speed[16] = { 0 }, elivation[16] = { 0 };
+int gps_valid = 0;
+
+static void
+nmea_txt_cb(void)
+{
+ char *ids[] = { "ERROR", "WARNING", "NOTICE", };
+
+ if (nmea_params[3].num < 0 || nmea_params[3].num > 2)
+ nmea_params[3].num = 0;
+
+ LOG("%s: %s\n", ids[nmea_params[3].num], nmea_params[4].str);
+}
+
+static void
+nmea_rmc_cb(void)
+{
+ struct tm tm;
+ char tmp[256];
+
+ if (*nmea_params[2].str != 'A') {
+ gps_valid = 0;
+ fprintf(stderr, "waiting for valid signal\n");
+ return;
+ }
+
+ gps_valid = 1;
+ memset(&tm, 0, sizeof(tm));
+ tm.tm_isdst = 1;
+
+ if (!strptime(nmea_params[1].str, "%H%M%S", &tm))
+ ERROR("failed to parse time\n");
+ else if (!strptime(nmea_params[9].str, "%d%m%y", &tm))
+ ERROR("failed to parse date\n");
+ else {
+ /* is there a libc api for the tz adjustment ? */
+ struct timeval tv = { mktime(&tm), 0 };
+ struct timeval cur;
+
+ strftime(tmp, 256, "%D %02H:%02M:%02S", &tm);
+ LOG("date: %s UTC\n", tmp);
+
+ tv.tv_sec -= timezone;
+ if (daylight)
+ tv.tv_sec += 3600;
+
+ gettimeofday(&cur, NULL);
+
+ if (abs(cur.tv_sec - tv.tv_sec) > MAX_TIME_OFFSET) {
+ if (++nmea_bad_time > MAX_BAD_TIME) {
+ LOG("system time differs from GPS time by more than %d seconds. Using %s UTC as the new time\n", MAX_TIME_OFFSET, tmp);
+ settimeofday(&tv, NULL);
+ }
+ } else {
+ nmea_bad_time = 0;
+ }
+ }
+
+ if (strlen(nmea_params[3].str) != 9 || strlen(nmea_params[5].str) != 10) {
+ ERROR("lat/lng have invalid string length\n");
+ } else {
+ int latd, latm, lats;
+ int lngd, lngm, lngs;
+ float flats, flngs;
+ LOG("position: %s, %s\n",
+ nmea_params[3].str, nmea_params[5].str);
+ latm = atoi(&nmea_params[3].str[2]);
+ nmea_params[3].str[2] = '\0';
+ latd = atoi(nmea_params[3].str);
+ lats = atoi(&nmea_params[3].str[5]);
+ if (*nmea_params[4].str != 'N')
+ latm *= -1;
+
+ lngm = atoi(&nmea_params[5].str[3]);
+ nmea_params[5].str[3] = '\0';
+ lngd = atoi(nmea_params[5].str);
+ lngs = atoi(&nmea_params[5].str[6]);
+ if (*nmea_params[6].str != 'E')
+ lngm *= -1;
+
+ flats = lats;
+ flats *= 60;
+ flats /= 10000;
+
+ flngs = lngs;
+ flngs *= 60;
+ flngs /= 10000;
+
+#define ms_to_deg(x, y) (((x * 10000) + y) / 60)
+
+ LOG("position: %d°%d.%04d, %d°%d.%04d\n",
+ latd, latm, lats, lngd, lngm, lngs);
+ LOG("position: %d°%d'%.1f\" %d°%d'%.1f\"\n",
+ latd, latm, flats, lngd, lngm, flngs);
+
+ snprintf(lattitude, sizeof(lattitude), "%d.%d", latd, ms_to_deg(latm, lats));
+ snprintf(longitude, sizeof(longitude), "%d.%d", lngd, ms_to_deg(lngm, lngs));
+ LOG("position: %s %s\n", lattitude, longitude);
+ gps_timestamp();
+ }
+}
+
+static void
+nmea_gga_cb(void)
+{
+ if (!gps_valid)
+ return;
+ strncpy(elivation, nmea_params[9].str, sizeof(elivation));
+ LOG("height: %s\n", elivation);
+}
+
+static void
+nmea_vtg_cb(void)
+{
+ if (!gps_valid)
+ return;
+ strncpy(course, nmea_params[1].str, sizeof(course));
+ strncpy(speed, nmea_params[6].str, sizeof(speed));
+ LOG("course: %s\n", course);
+ LOG("speed: %s\n", speed);
+}
+
+static struct nmea_msg {
+ char *msg;
+ int cnt;
+ void (*handler) (void);
+} nmea_msgs[] = {
+ {
+ .msg = "TXT",
+ .cnt = 5,
+ .handler = nmea_txt_cb,
+ }, {
+ .msg = "RMC",
+ .cnt = 11,
+ .handler = nmea_rmc_cb,
+ }, {
+ .msg = "GGA",
+ .cnt = 14,
+ .handler = nmea_gga_cb,
+ }, {
+ .msg = "VTG",
+ .cnt = 9,
+ .handler = nmea_vtg_cb,
+ },
+};
+
+static int
+nmea_verify_checksum(char *s)
+{
+ char *csum = strrchr(s, '*');
+ int isum, c = 0;
+
+ if (!csum)
+ return -1;
+
+ *csum = '\0';
+ csum++;
+ isum = strtol(csum, NULL, 16);
+
+ while(*s)
+ c ^= *s++;
+
+ if (isum != c)
+ return -1;
+
+ return 0;
+}
+
+static int
+nmea_tokenize(char *msg)
+{
+ int cnt = 0;
+ char *tok = strtok(msg, ",");
+
+ while (tok && cnt < MAX_NMEA_PARAM) {
+ nmea_params[cnt].str = tok;
+ nmea_params[cnt].num = atoi(tok);
+ cnt++;
+ tok = strtok(NULL, ",");
+ }
+
+ return cnt;
+}
+
+static void
+nmea_process(char *a)
+{
+ char *csum;
+ int cnt, i;
+
+ if (strncmp(a, "$GP", 3))
+ return;
+
+ a++;
+ csum = strrchr(a, '*');
+ if (!csum)
+ return;
+
+ if (nmea_verify_checksum(a)) {
+ ERROR("nmea message has invlid checksum\n");
+ return;
+ }
+
+ cnt = nmea_tokenize(&a[2]);
+ if (cnt < 0) {
+ ERROR("failed to tokenize %s\n", a);\
+ return;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(nmea_msgs); i++) {
+ if (strcmp(nmea_params[0].str, nmea_msgs[i].msg))
+ continue;
+ if (nmea_msgs[i].cnt <= cnt)
+ nmea_msgs[i].handler();
+ else
+ ERROR("%s datagram has wrong parameter count got %d but expected %d\n", nmea_msgs[i].msg, cnt, nmea_msgs[i].cnt);
+ return;
+ }
+}
+
+static int
+nmea_consume(struct ustream *s, char **a)
+{
+ char *eol = strstr(*a, "\n");
+
+ if (!eol)
+ return -1;
+
+ *eol++ = '\0';
+
+ nmea_process(*a);
+
+ ustream_consume(s, eol - *a);
+ *a = eol;
+
+ return 0;
+}
+
+static void
+nmea_msg_cb(struct ustream *s, int bytes)
+{
+ int len;
+ char *a = ustream_get_read_buf(s, &len);
+
+ while (!nmea_consume(s, &a))
+ ;
+}
+
+static void nmea_notify_cb(struct ustream *s)
+{
+ if (!s->eof)
+ return;
+
+ ERROR("tty error, shutting down\n");
+ exit(-1);
+}
+
+int
+nmea_open(char *dev, struct ustream_fd *s, speed_t speed)
+{
+ struct termios tio;
+ int tty;
+
+ tty = open(dev, O_RDWR | O_NOCTTY | O_NONBLOCK);
+ if (tty < 0) {
+ ERROR("%s: device open failed\n", dev);
+ return -1;
+ }
+
+ tcgetattr(tty, &tio);
+ tio.c_cflag |= CREAD;
+ tio.c_cflag |= CS8;
+ tio.c_iflag |= IGNPAR;
+ tio.c_lflag &= ~(ICANON);
+ tio.c_lflag &= ~(ECHO);
+ tio.c_lflag &= ~(ECHOE);
+ tio.c_lflag &= ~(ISIG);
+ tio.c_cc[VMIN] = 1;
+ tio.c_cc[VTIME] = 0;
+ cfsetispeed(&tio, speed);
+ cfsetospeed(&tio, speed);
+ tcsetattr(tty, TCSANOW, &tio);
+
+ s->stream.string_data = true;
+ s->stream.notify_read = nmea_msg_cb;
+ s->stream.notify_state = nmea_notify_cb;
+
+ ustream_fd_init(s, tty);
+
+ tcflush(tty, TCIFLUSH);
+
+ return 0;
+}
projects / project / ugps.git / commitdiff