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decode_aprs.c
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//
// This file is part of Dire Wolf, an amateur radio packet TNC.
//
// Copyright (C) 2011,2012,2013,2014 John Langner, WB2OSZ
//
// 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, see <http://www.gnu.org/licenses/>.
//
/*------------------------------------------------------------------
*
* File: decode_aprs.c
*
* Purpose: Decode the information part of APRS frame.
*
* Description: Present the packet contents in human readable format.
* This is a fairly complete implementation with error messages
* pointing out various specication violations.
*
*
*
* Assumptions: ax25_from_frame() has been called to
* separate the header and information.
*
*
*------------------------------------------------------------------*/
#include <stdio.h>
#include <time.h>
#include <assert.h>
#include <stdlib.h> /* for atof */
#include <string.h> /* for strtok */
#if __WIN32__
char *strsep(char **stringp, const char *delim);
#endif
#include <math.h> /* for pow */
#include <ctype.h> /* for isdigit */
#include <fcntl.h>
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 1
#endif
#include "regex.h"
#include "direwolf.h"
#include "ax25_pad.h"
#include "textcolor.h"
#include "symbols.h"
#include "latlong.h"
#define TRUE 1
#define FALSE 0
#define METERS_TO_FEET(x) ((x) * 3.2808399)
#define KNOTS_TO_MPH(x) ((x) * 1.15077945)
#define KM_TO_MILES(x) ((x) * 0.621371192)
#define MBAR_TO_INHG(x) ((x) * 0.0295333727)
/* Position & symbol fields common to several message formats. */
typedef struct {
char lat[8];
char sym_table_id; /* / \ 0-9 A-Z */
char lon[9];
char symbol_code;
} position_t;
typedef struct {
char sym_table_id; /* / \ a-j A-Z */
/* "The presence of the leading Symbol Table Identifier */
/* instead of a digit indicates that this is a compressed */
/* Position Report and not a normal lat/long report." */
/* "a-j" is not a typographical error. */
/* The first 10 lower case letters represent the overlay */
/* characters of 0-9 in the compressed format. */
char y[4]; /* Compressed Latitude. */
char x[4]; /* Compressed Longitude. */
char symbol_code;
char c; /* Course/speed or altitude. */
char s;
char t ; /* Compression type. */
} compressed_position_t;
static void print_decoded (void);
static void aprs_ll_pos (unsigned char *, int);
static void aprs_ll_pos_time (unsigned char *, int);
static void aprs_raw_nmea (unsigned char *, int);
static void aprs_mic_e (packet_t, unsigned char *, int);
//static void aprs_compressed_pos (unsigned char *, int);
static void aprs_message (unsigned char *, int);
static void aprs_object (unsigned char *, int);
static void aprs_item (unsigned char *, int);
static void aprs_station_capabilities (char *, int);
static void aprs_status_report (char *, int);
static void aprs_telemetry (char *, int);
static void aprs_raw_touch_tone (char *, int);
static void aprs_morse_code (char *, int);
static void aprs_positionless_weather_report (unsigned char *, int);
static void weather_data (char *wdata, int wind_prefix);
static void aprs_ultimeter (char *, int);
static void third_party_header (char *, int);
static void decode_position (position_t *ppos);
static void decode_compressed_position (compressed_position_t *ppos);
static double get_latitude_8 (char *p);
static double get_longitude_9 (char *p);
static double get_latitude_nmea (char *pstr, char *phemi);
static double get_longitude_nmea (char *pstr, char *phemi);
static time_t get_timestamp (char *p);
static int get_maidenhead (char *p);
static int data_extension_comment (char *pdext);
static void decode_tocall (char *dest);
//static void get_symbol (char dti, char *src, char *dest);
static void process_comment (char *pstart, int clen);
/*
* Information extracted from the message.
*/
/* for unknown values. */
//#define G_UNKNOWN -999999
static char g_msg_type[30]; /* Message type. */
static char g_symbol_table; /* The Symbol Table Identifier character selects one */
/* of the two Symbol Tables, or it may be used as */
/* single-character (alpha or numeric) overlay, as follows: */
/* / Primary Symbol Table (mostly stations) */
/* \ Alternate Symbol Table (mostly Objects) */
/* 0-9 Numeric overlay. Symbol from Alternate Symbol */
/* Table (uncompressed lat/long data format) */
/* a-j Numeric overlay. Symbol from Alternate */
/* Symbol Table (compressed lat/long data */
/* format only). i.e. a-j maps to 0-9 */
/* A-Z Alpha overlay. Symbol from Alternate Symbol Table */
static char g_symbol_code; /* Where the Symbol Table Identifier is 0-9 or A-Z (or a-j */
/* with compressed position data only), the symbol comes from */
/* the Alternate Symbol Table, and is overlaid with the */
/* identifier (as a single digit or a capital letter). */
static double g_lat, g_lon; /* Location, degrees. Negative for South or West. */
/* Set to G_UNKNOWN if missing or error. */
static char g_maidenhead[9]; /* 4 or 6 (or 8?) character maidenhead locator. */
static char g_name[20]; /* Object or item name. */
static float g_speed; /* Speed in MPH. */
static float g_course; /* 0 = North, 90 = East, etc. */
static int g_power; /* Transmitter power in watts. */
static int g_height; /* Antenna height above average terrain, feet. */
static int g_gain; /* Antenna gain in dB. */
static char g_directivity[10]; /* Direction of max signal strength */
static float g_range; /* Precomputed radio range in miles. */
static float g_altitude; /* Feet above median sea level. */
static char g_mfr[80]; /* Manufacturer or application. */
static char g_mic_e_status[30]; /* MIC-E message. */
static char g_freq[40]; /* Frequency, tone, xmit offset */
static char g_comment[256]; /* Comment. */
/*------------------------------------------------------------------
*
* Function: decode_aprs
*
* Purpose: Optionally print packet then decode it.
*
* Inputs: src - Source Station.
*
* The SSID is used as a last resort for the
* displayed symbol if not specified in any other way.
*
* dest - Destination Station.
*
* Certain destinations (GPSxxx, SPCxxx, SYMxxx) can
* be used to specify the display symbol.
* For the MIC-E format (used by Kenwood D7, D700), the
* "destination" is really the latitude.
*
* pinfo - pointer to information field.
* info_len - length of the information field.
*
* Outputs: Variables above:
*
* g_symbol_table, g_symbol_code,
* g_lat, g_lon,
* g_speed, g_course, g_altitude,
* g_comment
* ... and others...
*
* Other functions are then called to retrieve the information.
*
* Bug: This is not thread-safe because it uses static data and strtok.
*
*------------------------------------------------------------------*/
void decode_aprs (packet_t pp)
{
//int naddr;
//int err;
char src[AX25_MAX_ADDR_LEN], dest[AX25_MAX_ADDR_LEN];
//char *p;
//int ssid;
unsigned char *pinfo;
int info_len;
info_len = ax25_get_info (pp, &pinfo);
sprintf (g_msg_type, "Unknown message type %c", *pinfo);
g_symbol_table = '/';
g_symbol_code = ' '; /* What should we have for default? */
g_lat = G_UNKNOWN;
g_lon = G_UNKNOWN;
strcpy (g_maidenhead, "");
strcpy (g_name, "");
g_speed = G_UNKNOWN;
g_course = G_UNKNOWN;
g_power = G_UNKNOWN;
g_height = G_UNKNOWN;
g_gain = G_UNKNOWN;
strcpy (g_directivity, "");
g_range = G_UNKNOWN;
g_altitude = G_UNKNOWN;
strcpy(g_mfr, "");
strcpy(g_mic_e_status, "");
strcpy(g_freq, "");
strcpy (g_comment, "");
/*
* Extract source and destination including the SSID.
*/
ax25_get_addr_with_ssid (pp, AX25_SOURCE, src);
ax25_get_addr_with_ssid (pp, AX25_DESTINATION, dest);
switch (*pinfo) { /* "DTI" data type identifier. */
case '!': /* Position without timestamp (no APRS messaging). */
/* or Ultimeter 2000 WX Station */
case '=': /* Position without timestamp (with APRS messaging). */
if (strncmp((char*)pinfo, "!!", 2) == 0)
{
aprs_ultimeter ((char*)pinfo, info_len);
}
else
{
aprs_ll_pos (pinfo, info_len);
}
break;
//case '#': /* Peet Bros U-II Weather station */
//case '*': /* Peet Bros U-II Weather station */
//break;
case '$': /* Raw GPS data or Ultimeter 2000 */
if (strncmp((char*)pinfo, "$ULTW", 5) == 0)
{
aprs_ultimeter ((char*)pinfo, info_len);
}
else
{
aprs_raw_nmea (pinfo, info_len);
}
break;
case '\'': /* Old Mic-E Data (but Current data for TM-D700) */
case '`': /* Current Mic-E Data (not used in TM-D700) */
aprs_mic_e (pp, pinfo, info_len);
break;
case ')': /* Item. */
aprs_item (pinfo, info_len);
break;
case '/': /* Position with timestamp (no APRS messaging) */
case '@': /* Position with timestamp (with APRS messaging) */
aprs_ll_pos_time (pinfo, info_len);
break;
case ':': /* Message */
aprs_message (pinfo, info_len);
break;
case ';': /* Object */
aprs_object (pinfo, info_len);
break;
case '<': /* Station Capabilities */
aprs_station_capabilities ((char*)pinfo, info_len);
break;
case '>': /* Status Report */
aprs_status_report ((char*)pinfo, info_len);
break;
//case '?': /* Query */
//break;
case 'T': /* Telemetry */
aprs_telemetry ((char*)pinfo, info_len);
break;
case '_': /* Positionless Weather Report */
aprs_positionless_weather_report (pinfo, info_len);
break;
case '{': /* user defined data */
/* http://www.aprs.org/aprs11/expfmts.txt */
if (strncmp((char*)pinfo, "{tt", 3) == 0) {
aprs_raw_touch_tone (pinfo, info_len);
}
else if (strncmp((char*)pinfo, "{mc", 3) == 0) {
aprs_morse_code ((char*)pinfo, info_len);
}
else {
//aprs_user_defined (pinfo, info_len);
}
break;
case 't': /* Raw touch tone data - NOT PART OF STANDARD */
/* Used to convey raw touch tone sequences to */
/* to an application that might want to interpret them. */
/* Might move into user defined data, above. */
aprs_raw_touch_tone ((char*)pinfo, info_len);
break;
case 'm': /* Morse Code data - NOT PART OF STANDARD */
/* Used by APRStt gateway to put audible responses */
/* into the transmit queue. Could potentially find */
/* other uses such as CW ID for station. */
/* Might move into user defined data, above. */
aprs_morse_code ((char*)pinfo, info_len);
break;
case '}': /* third party header */
third_party_header ((char*)pinfo, info_len);
break;
//case '\r': /* CR or LF? */
//case '\n':
//break;
default:
break;
}
/*
* Look in other locations if not found in information field.
*/
if (g_symbol_table == ' ' || g_symbol_code == ' ') {
symbols_from_dest_or_src (*pinfo, src, dest, &g_symbol_table, &g_symbol_code);
}
/*
* Application might be in the destination field for most message types.
* MIC-E format has part of location in the destination field.
*/
switch (*pinfo) { /* "DTI" data type identifier. */
case '\'': /* Old Mic-E Data */
case '`': /* Current Mic-E Data */
break;
default:
decode_tocall (dest);
break;
}
/*
* Print it all out in human readable format.
*/
print_decoded ();
}
static void print_decoded (void) {
char stemp[200];
char tmp2[2];
double absll;
char news;
int deg;
double min;
char s_lat[30];
char s_lon[30];
int n;
char symbol_description[100];
/*
* First line has:
* - message type
* - object name
* - symbol
* - manufacturer/application
* - mic-e status
* - power/height/gain, range
*/
strcpy (stemp, g_msg_type);
if (strlen(g_name) > 0) {
strcat (stemp, ", \"");
strcat (stemp, g_name);
strcat (stemp, "\"");
}
symbols_get_description (g_symbol_table, g_symbol_code, symbol_description);
strcat (stemp, ", ");
strcat (stemp, symbol_description);
if (strlen(g_mfr) > 0) {
strcat (stemp, ", ");
strcat (stemp, g_mfr);
}
if (strlen(g_mic_e_status) > 0) {
strcat (stemp, ", ");
strcat (stemp, g_mic_e_status);
}
if (g_power > 0) {
char phg[100];
sprintf (phg, ", %d W height=%d %ddBi %s", g_power, g_height, g_gain, g_directivity);
strcat (stemp, phg);
}
if (g_range > 0) {
char rng[100];
sprintf (rng, ", range=%.1f", g_range);
strcat (stemp, rng);
}
text_color_set(DW_COLOR_DECODED);
dw_printf("%s\n", stemp);
/*
* Second line has:
* - Latitude
* - Longitude
* - speed
* - direction
* - altitude
* - frequency
*/
/*
* Convert Maidenhead locator to latitude and longitude.
*
* Any example was checked for each hemihemisphere using
* http://www.amsat.org/cgi-bin/gridconv
*
* Bug: This does not check for invalid values.
*/
if (strlen(g_maidenhead) > 0) {
dw_printf("Grid square = %s, ", g_maidenhead);
if (g_lat == G_UNKNOWN && g_lon == G_UNKNOWN) {
g_lon = (toupper(g_maidenhead[0]) - 'A') * 20 - 180;
g_lat = (toupper(g_maidenhead[1]) - 'A') * 10 - 90;
g_lon += (g_maidenhead[2] - '0') * 2;
g_lat += (g_maidenhead[3] - '0');
if (strlen(g_maidenhead) >=6) {
g_lon += (toupper(g_maidenhead[4]) - 'A') * 5.0 / 60.0;
g_lat += (toupper(g_maidenhead[5]) - 'A') * 2.5 / 60.0;
g_lon += 2.5 / 60.0; /* Move from corner to center of square */
g_lat += 1.25 / 60.0;
}
else {
g_lon += 1.0; /* Move from corner to center of square */
g_lat += 0.5;
}
}
}
strcpy (stemp, "");
if (g_lat != G_UNKNOWN || g_lon != G_UNKNOWN) {
// Have location but it is posible one part is invalid.
if (g_lat != G_UNKNOWN) {
if (g_lat >= 0) {
absll = g_lat;
news = 'N';
}
else {
absll = - g_lat;
news = 'S';
}
deg = (int) absll;
min = (absll - deg) * 60.0;
sprintf (s_lat, "%c %02d%s%07.4f", news, deg, CH_DEGREE, min);
}
else {
strcpy (s_lat, "Invalid Latitude");
}
if (g_lon != G_UNKNOWN) {
if (g_lon >= 0) {
absll = g_lon;
news = 'E';
}
else {
absll = - g_lon;
news = 'W';
}
deg = (int) absll;
min = (absll - deg) * 60.0;
sprintf (s_lon, "%c %03d%s%07.4f", news, deg, CH_DEGREE, min);
}
else {
strcpy (s_lon, "Invalid Longitude");
}
sprintf (stemp, "%s, %s", s_lat, s_lon);
}
if (g_speed != G_UNKNOWN) {
char spd[20];
if (strlen(stemp) > 0) strcat (stemp, ", ");
sprintf (spd, "%.0f MPH", g_speed);
strcat (stemp, spd);
};
if (g_course != G_UNKNOWN) {
char cse[20];
if (strlen(stemp) > 0) strcat (stemp, ", ");
sprintf (cse, "course %.0f", g_course);
strcat (stemp, cse);
};
if (g_altitude != G_UNKNOWN) {
char alt[20];
if (strlen(stemp) > 0) strcat (stemp, ", ");
sprintf (alt, "alt %.0f ft", g_altitude);
strcat (stemp, alt);
};
if (strlen(g_freq) > 0) {
strcat (stemp, ", ");
strcat (stemp, g_freq);
}
if (strlen (stemp) > 0) {
text_color_set(DW_COLOR_DECODED);
dw_printf("%s\n", stemp);
}
/*
* Third line has:
* - comment or weather
*
* Non-printable characters are changed to safe hexadecimal representations.
* For example, carriage return is displayed as <0x0d>.
*
* Drop annoying trailing CR LF. Anyone who cares can see it in the raw data.
*/
n = strlen(g_comment);
if (n >= 1 && g_comment[n-1] == '\n') {
g_comment[n-1] = '\0';
n--;
}
if (n >= 1 && g_comment[n-1] == '\r') {
g_comment[n-1] = '\0';
n--;
}
if (n > 0) {
int j;
ax25_safe_print (g_comment, -1, 0);
dw_printf("\n");
/*
* Point out incorrect attempts a degree symbol.
* 0xb0 is degree in ISO Latin1.
* To be part of a valid UTF-8 sequence, it would need to be preceded by 11xxxxxx or 10xxxxxx.
* 0xf8 is degree in Microsoft code page 437.
* To be part of a valid UTF-8 sequence, it would need to be followed by 10xxxxxx.
*/
for (j=0; j<n; j++) {
if ((unsigned)g_comment[j] == (char)0xb0 && (j == 0 || ! (g_comment[j-1] & 0x80))) {
text_color_set(DW_COLOR_ERROR);
dw_printf("Character code 0xb0 is probably an attempt at a degree symbol.\n");
dw_printf("The correct encoding is 0xc2 0xb0 in UTF-8.\n");
}
}
for (j=0; j<n; j++) {
if ((unsigned)g_comment[j] == (char)0xf8 && (j == n-1 || (g_comment[j+1] & 0xc0) != 0xc0)) {
text_color_set(DW_COLOR_ERROR);
dw_printf("Character code 0xf8 is probably an attempt at a degree symbol.\n");
dw_printf("The correct encoding is 0xc2 0xb0 in UTF-8.\n");
}
}
}
}
/*------------------------------------------------------------------
*
* Function: aprs_ll_pos
*
* Purpose: Decode "Lat/Long Position Report - without Timestamp"
*
* Reports without a timestamp can be regarded as real-time.
*
* Inputs: info - Pointer to Information field.
* ilen - Information field length.
*
* Outputs: g_lat, g_lon, g_symbol_table, g_symbol_code, g_speed, g_course, g_altitude.
*
* Description: Type identifier '=' has APRS messaging.
* Type identifier '!' does not have APRS messaging.
*
* The location can be in either compressed or human-readable form.
*
* When the symbol code is '_' this is a weather report.
*
* Examples: !4309.95NS07307.13W#PHG3320 W2,NY2 Mt Equinox VT k2lm@arrl.net
* !4237.14NS07120.83W#
* =4246.40N/07115.15W# {UIV32}
*
* TODO: (?) Special case, DF report when sym table id = '/' and symbol code = '\'.
*
* =4903.50N/07201.75W\088/036/270/729
*
*------------------------------------------------------------------*/
static void aprs_ll_pos (unsigned char *info, int ilen)
{
struct aprs_ll_pos_s {
char dti; /* ! or = */
position_t pos;
char comment[43]; /* Start of comment could be data extension(s). */
} *p;
struct aprs_compressed_pos_s {
char dti; /* ! or = */
compressed_position_t cpos;
char comment[40]; /* No data extension allowed for compressed location. */
} *q;
strcpy (g_msg_type, "Position");
p = (struct aprs_ll_pos_s *)info;
q = (struct aprs_compressed_pos_s *)info;
if (isdigit((unsigned char)(p->pos.lat[0]))) /* Human-readable location. */
{
decode_position (&(p->pos));
if (g_symbol_code == '_') {
/* Symbol code indidates it is a weather report. */
/* In this case, we expect 7 byte "data extension" */
/* for the wind direction and speed. */
strcpy (g_msg_type, "Weather Report");
weather_data (p->comment, TRUE);
}
else {
/* Regular position report. */
data_extension_comment (p->comment);
}
}
else /* Compressed location. */
{
decode_compressed_position (&(q->cpos));
if (g_symbol_code == '_') {
/* Symbol code indidates it is a weather report. */
/* In this case, the wind direction and speed are in the */
/* compressed data so we don't expect a 7 byte "data */
/* extension" for them. */
strcpy (g_msg_type, "Weather Report");
weather_data (q->comment, FALSE);
}
else {
/* Regular position report. */
process_comment (q->comment, -1);
}
}
}
/*------------------------------------------------------------------
*
* Function: aprs_ll_pos_time
*
* Purpose: Decode "Lat/Long Position Report - with Timestamp"
*
* Reports sent with a timestamp might contain very old information.
*
* Otherwise, same as above.
*
* Inputs: info - Pointer to Information field.
* ilen - Information field length.
*
* Outputs: g_lat, g_lon, g_symbol_table, g_symbol_code, g_speed, g_course, g_altitude.
*
* Description: Type identifier '@' has APRS messaging.
* Type identifier '/' does not have APRS messaging.
*
* The location can be in either compressed or human-readable form.
*
* When the symbol code is '_' this is a weather report.
*
* Examples: @041025z4232.32N/07058.81W_124/000g000t036r000p000P000b10229h65/wx rpt
* @281621z4237.55N/07120.20W_017/002g006t022r000p000P000h85b10195.Dvs
* /092345z4903.50N/07201.75W>Test1234
*
* I think the symbol code of "_" indicates weather report.
*
* (?) Special case, DF report when sym table id = '/' and symbol code = '\'.
*
* @092345z4903.50N/07201.75W\088/036/270/729
* /092345z4903.50N/07201.75W\000/000/270/729
*
*------------------------------------------------------------------*/
static void aprs_ll_pos_time (unsigned char *info, int ilen)
{
struct aprs_ll_pos_time_s {
char dti; /* / or @ */
char time_stamp[7];
position_t pos;
char comment[43]; /* First 7 bytes could be data extension. */
} *p;
struct aprs_compressed_pos_time_s {
char dti; /* / or @ */
char time_stamp[7];
compressed_position_t cpos;
char comment[40]; /* No data extension in this case. */
} *q;
strcpy (g_msg_type, "Position with time");
time_t ts = 0;
p = (struct aprs_ll_pos_time_s *)info;
q = (struct aprs_compressed_pos_time_s *)info;
if (isdigit((unsigned char)(p->pos.lat[0]))) /* Human-readable location. */
{
ts = get_timestamp (p->time_stamp);
decode_position (&(p->pos));
if (g_symbol_code == '_') {
/* Symbol code indidates it is a weather report. */
/* In this case, we expect 7 byte "data extension" */
/* for the wind direction and speed. */
strcpy (g_msg_type, "Weather Report");
weather_data (p->comment, TRUE);
}
else {
/* Regular position report. */
data_extension_comment (p->comment);
}
}
else /* Compressed location. */
{
ts = get_timestamp (p->time_stamp);
decode_compressed_position (&(q->cpos));
if (g_symbol_code == '_') {
/* Symbol code indidates it is a weather report. */
/* In this case, the wind direction and speed are in the */
/* compressed data so we don't expect a 7 byte "data */
/* extension" for them. */
strcpy (g_msg_type, "Weather Report");
weather_data (q->comment, FALSE);
}
else {
/* Regular position report. */
process_comment (q->comment, -1);
}
}
}
/*------------------------------------------------------------------
*
* Function: aprs_raw_nmea
*
* Purpose: Decode "Raw NMEA Position Report"
*
* Inputs: info - Pointer to Information field.
* ilen - Information field length.
*
* Outputs: ??? TBD
*
* Description: APRS recognizes raw ASCII data strings conforming to the NMEA 0183
* Version 2.0 specification, originating from navigation equipment such
* as GPS and LORAN receivers. It is recommended that APRS stations
* interpret at least the following NMEA Received Sentence types:
*
* GGA Global Positioning System Fix Data
* GLL Geographic Position, Latitude/Longitude Data
* RMC Recommended Minimum Specific GPS/Transit Data
* VTG Velocity and Track Data
* WPL Way Point Location
*
* Examples: $GPGGA,102705,5157.9762,N,00029.3256,W,1,04,2.0,75.7,M,47.6,M,,*62
* $GPGLL,2554.459,N,08020.187,W,154027.281,A
* $GPRMC,063909,A,3349.4302,N,11700.3721,W,43.022,89.3,291099,13.6,E*52
* $GPVTG,318.7,T,,M,35.1,N,65.0,K*69
*
*
*------------------------------------------------------------------*/
static void nmea_checksum (char *sent)
{
char *p;
char *next;
unsigned char cs;
// Do we have valid checksum?
cs = 0;
for (p = sent+1; *p != '*' && *p != '\0'; p++) {
cs ^= *p;
}
p = strchr (sent, '*');
if (p == NULL) {
text_color_set (DW_COLOR_INFO);
dw_printf("Missing GPS checksum.\n");
return;
}
if (cs != strtoul(p+1, NULL, 16)) {
text_color_set (DW_COLOR_ERROR);
dw_printf("GPS checksum error. Expected %02x but found %s.\n", cs, p+1);
return;
}
*p = '\0'; // Remove the checksum.
}
static void aprs_raw_nmea (unsigned char *info, int ilen)
{
char stemp[256];
char *ptype;
char *next;
strcpy (g_msg_type, "Raw NMEA");
strncpy (stemp, (char *)info, ilen);
stemp[ilen] = '\0';
nmea_checksum (stemp);
next = stemp;
ptype = strsep(&next, ",");
if (strcmp(ptype, "$GPGGA") == 0)
{
char *ptime; /* Time, hhmmss[.sss] */
char *plat; /* Latitude */
char *pns; /* North/South */
char *plon; /* Longitude */
char *pew; /* East/West */
char *pquality; /* Fix Quality: 0=invalid, 1=GPS, 2=DGPS */
char *pnsat; /* Number of satellites. */
char *phdop; /* Horizontal dilution of precision. */
char *paltitude; /* Altitude, meters above mean sea level. */
char *pm; /* "M" = meters */
/* Various other stuff... */
ptime = strsep(&next, ",");
plat = strsep(&next, ",");
pns = strsep(&next, ",");
plon = strsep(&next, ",");
pew = strsep(&next, ",");
pquality = strsep(&next, ",");
pnsat = strsep(&next, ",");
phdop = strsep(&next, ",");
paltitude = strsep(&next, ",");
pm = strsep(&next, ",");
/* Process time??? */
if (plat != NULL && strlen(plat) > 0) {
g_lat = get_latitude_nmea(plat, pns);
}
if (plon != NULL && strlen(plon) > 0) {
g_lon = get_longitude_nmea(plon, pew);
}
if (paltitude != NULL && strlen(paltitude) > 0) {
g_altitude = METERS_TO_FEET(atof(paltitude));
}
}
else if (strcmp(ptype, "$GPGLL") == 0)