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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, 2015, 2017, 2022 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 specification violations.
*
* Assumptions: ax25_from_frame() has been called to
* separate the header and information.
*
*------------------------------------------------------------------*/
#include "direwolf.h"
#include <stdio.h>
#include <time.h>
#include <assert.h>
#include <stdlib.h> /* for atof */
#include <string.h> /* for strtok */
#include <math.h> /* for pow */
#include <ctype.h> /* for isdigit */
#include <fcntl.h>
#include "regex.h"
#include "ax25_pad.h"
#include "textcolor.h"
#include "symbols.h"
#include "latlong.h"
#include "dwgpsnmea.h"
#include "decode_aprs.h"
#include "telemetry.h"
#include "ais.h"
#define TRUE 1
#define FALSE 0
/* 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;
/* Range of digits for Base 91 representation. */
#define B91_MIN '!'
#define B91_MAX '{'
#define isdigit91(c) ((c) >= B91_MIN && (c) <= B91_MAX)
//static void print_decoded (decode_aprs_t *A);
static void aprs_ll_pos (decode_aprs_t *A, unsigned char *, int);
static void aprs_ll_pos_time (decode_aprs_t *A, unsigned char *, int);
static void aprs_raw_nmea (decode_aprs_t *A, unsigned char *, int);
static void aprs_mic_e (decode_aprs_t *A, packet_t, unsigned char *, int);
//static void aprs_compressed_pos (decode_aprs_t *A, unsigned char *, int);
static void aprs_message (decode_aprs_t *A, unsigned char *, int, int quiet);
static void aprs_object (decode_aprs_t *A, unsigned char *, int);
static void aprs_item (decode_aprs_t *A, unsigned char *, int);
static void aprs_station_capabilities (decode_aprs_t *A, char *, int);
static void aprs_status_report (decode_aprs_t *A, char *, int);
static void aprs_general_query (decode_aprs_t *A, char *, int, int quiet);
static void aprs_directed_station_query (decode_aprs_t *A, char *addressee, char *query, int quiet);
static void aprs_telemetry (decode_aprs_t *A, char *info, int info_len, int quiet);
static void aprs_user_defined (decode_aprs_t *A, char *, int);
static void aprs_raw_touch_tone (decode_aprs_t *A, char *, int);
static void aprs_morse_code (decode_aprs_t *A, char *, int);
static void aprs_positionless_weather_report (decode_aprs_t *A, unsigned char *, int);
static void weather_data (decode_aprs_t *A, char *wdata, int wind_prefix);
static void aprs_ultimeter (decode_aprs_t *A, char *, int);
static void decode_position (decode_aprs_t *A, position_t *ppos);
static void decode_compressed_position (decode_aprs_t *A, compressed_position_t *ppos);
static double get_latitude_8 (char *p, int quiet);
static double get_longitude_9 (char *p, int quiet);
static time_t get_timestamp (decode_aprs_t *A, char *p);
static int get_maidenhead (decode_aprs_t *A, char *p);
static int data_extension_comment (decode_aprs_t *A, char *pdext);
static void decode_tocall (decode_aprs_t *A, char *dest);
//static void get_symbol (decode_aprs_t *A, char dti, char *src, char *dest);
static void process_comment (decode_aprs_t *A, char *pstart, int clen);
/*------------------------------------------------------------------
*
* Function: decode_aprs
*
* Purpose: Split APRS packet into separate properties that it contains.
*
* Inputs: pp - APRS packet object.
*
* quiet - Suppress error messages.
*
* third_party - True when parsing a third party header.
* (decode_aprs is called recursively.)
* This is mostly found when an IGate transmits a message
* that came via APRS-IS.
*
* Outputs: A-> g_symbol_table, g_symbol_code,
* g_lat, g_lon,
* g_speed_mph, g_course, g_altitude_ft,
* g_comment
* ... and many others...
*
* Major Revisions: 1.1 Reorganized so parts are returned in a structure.
* Print function is now called separately.
*
*------------------------------------------------------------------*/
void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet, int third_party)
{
//dw_printf ("DEBUG decode_aprs quiet=%d, third_party=%d\n", quiet, third_party);
//char dest[AX25_MAX_ADDR_LEN];
unsigned char *pinfo;
int info_len;
info_len = ax25_get_info (pp, &pinfo);
//dw_printf ("DEBUG decode_aprs info=\"%s\"\n", pinfo);
memset (A, 0, sizeof (*A));
A->g_quiet = quiet;
if (isprint(*pinfo)) {
snprintf (A->g_data_type_desc, sizeof(A->g_data_type_desc), "Unknown APRS Data Type Indicator \"%c\"", *pinfo);
}
else {
snprintf (A->g_data_type_desc, sizeof(A->g_data_type_desc), "ERROR!!! Unknown APRS Data Type Indicator: unprintable 0x%02x", *pinfo);
}
A->g_symbol_table = '/'; /* Default to primary table. */
A->g_symbol_code = ' '; /* What should we have for default symbol? */
A->g_lat = G_UNKNOWN;
A->g_lon = G_UNKNOWN;
A->g_speed_mph = G_UNKNOWN;
A->g_course = G_UNKNOWN;
A->g_power = G_UNKNOWN;
A->g_height = G_UNKNOWN;
A->g_gain = G_UNKNOWN;
A->g_range = G_UNKNOWN;
A->g_altitude_ft = G_UNKNOWN;
A->g_freq = G_UNKNOWN;
A->g_tone = G_UNKNOWN;
A->g_dcs = G_UNKNOWN;
A->g_offset = G_UNKNOWN;
A->g_footprint_lat = G_UNKNOWN;
A->g_footprint_lon = G_UNKNOWN;
A->g_footprint_radius = G_UNKNOWN;
// If third-party header, try to decode just the payload.
if (*pinfo == '}') {
//dw_printf ("DEBUG decode_aprs recursively process third party header\n");
// This must not be strict because the addresses in third party payload doesn't
// need to adhere to the AX.25 address format (i.e. 6 upper case alphanumeric.)
// SSID can be 2 alphanumeric characters.
// Addresses can include lower case, e.g. q contruct.
// e.g. WR2X-2>APRS,WA1PLE-13*:}
// K1BOS-B>APOSB,TCPIP,WR2X-2*:@122015z4221.42ND07111.93W&/A=000000SharkRF openSPOT3 MMDVM446.025 MA/SW
packet_t pp_payload = ax25_from_text ((char*)pinfo+1, 0);
if (pp_payload != NULL) {
decode_aprs (A, pp_payload, quiet, 1); // 1 means used recursively
ax25_delete (pp_payload);
return;
}
else {
strlcpy (A->g_data_type_desc, "Third Party Header: Unable to parse payload.", sizeof(A->g_data_type_desc));
ax25_get_addr_with_ssid (pp, AX25_SOURCE, A->g_src);
ax25_get_addr_with_ssid (pp, AX25_DESTINATION, A->g_dest);
}
}
/*
* Extract source and destination including the SSID.
*/
ax25_get_addr_with_ssid (pp, AX25_SOURCE, A->g_src);
ax25_get_addr_with_ssid (pp, AX25_DESTINATION, A->g_dest);
//dw_printf ("DEBUG decode_aprs source=%s, dest=%s\n", A->g_src, A->g_dest);
/*
* Report error if the information part contains a nul character.
* There are two known cases where this can happen.
*
* - The Kenwood TM-D710A sometimes sends packets like this:
*
* VA3AJ-9>T2QU6X,VE3WRC,WIDE1,K8UNS,WIDE2*:4P<0x00><0x0f>4T<0x00><0x0f>4X<0x00><0x0f>4\<0x00>`nW<0x1f>oS8>/]"6M}driving fast=
* K4JH-9>S5UQ6X,WR4AGC-3*,WIDE1*:4P<0x00><0x0f>4T<0x00><0x0f>4X<0x00><0x0f>4\<0x00>`jP}l"&>/]"47}QRV from the EV =
*
* Notice that the data type indicator of "4" is not valid. If we remove
* 4P<0x00><0x0f>4T<0x00><0x0f>4X<0x00><0x0f>4\<0x00> we are left with a good MIC-E format.
* This same thing has been observed from others and is intermittent.
*
* - AGW Tracker can send UTF-16 if an option is selected. This can introduce nul bytes.
* This is wrong, it should be using UTF-8.
*/
if ( ( ! A->g_quiet ) && ( (int)strlen((char*)pinfo) != info_len) ) {
text_color_set(DW_COLOR_ERROR);
dw_printf("'nul' character found in Information part. This should never happen with APRS.\n");
dw_printf("If this is meant to be APRS, %s is transmitting with defective software.\n", A->g_src);
if (strcmp((char*)pinfo, "4P") == 0) {
dw_printf("The TM-D710 will do this intermittently. A firmware upgrade is needed to fix it.\n");
}
}
/*
* 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 (A, A->g_dest);
break;
}
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 (A, (char*)pinfo, info_len);
}
else
{
aprs_ll_pos (A, 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 (A, (char*)pinfo, info_len);
}
else
{
aprs_raw_nmea (A, 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 (A, pp, pinfo, info_len);
break;
case ')': /* Item. */
aprs_item (A, pinfo, info_len);
break;
case '/': /* Position with timestamp (no APRS messaging) */
case '@': /* Position with timestamp (with APRS messaging) */
aprs_ll_pos_time (A, pinfo, info_len);
break;
case ':': /* "Message" (special APRS meaning): for one person, a group, or a bulletin. */
/* Directed Station Query */
/* Telemetry metadata. */
aprs_message (A, pinfo, info_len, quiet);
break;
case ';': /* Object */
aprs_object (A, pinfo, info_len);
break;
case '<': /* Station Capabilities */
aprs_station_capabilities (A, (char*)pinfo, info_len);
break;
case '>': /* Status Report */
aprs_status_report (A, (char*)pinfo, info_len);
break;
case '?': /* General Query */
aprs_general_query (A, (char*)pinfo, info_len, quiet);
break;
case 'T': /* Telemetry */
aprs_telemetry (A, (char*)pinfo, info_len, quiet);
break;
case '_': /* Positionless Weather Report */
aprs_positionless_weather_report (A, pinfo, info_len);
break;
case '{': /* user defined data */
aprs_user_defined (A, (char*)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 (A, (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 (A, (char*)pinfo, info_len);
break;
//case '}': /* third party header */
// was already caught earlier.
//case '\r': /* CR or LF? */
//case '\n':
//break;
default:
break;
}
/*
* Priority order for determining the symbol is:
* - Information part, where appropriate. Already done above.
* - Destination field starting with GPS, SPC, or SYM.
* - Source SSID - Confusing to most people. Even I forgot about it when
* someone questioned where the symbol came from. It's in the APRS
* protocol spec, end of Chapter 20.
*/
if (A->g_symbol_table == ' ' || A->g_symbol_code == ' ') {
// A symbol on a "message" makes no sense and confuses people.
// Third party too. Set from the payload.
// Maybe eliminate for a couple others.
//dw_printf ("DEBUG decode_aprs@end1 third_party=%d, symbol_table=%c, symbol_code=%c, *pinfo=%c\n", third_party, A->g_symbol_table, A->g_symbol_code, *pinfo);
if (*pinfo != ':' && *pinfo != '}') {
symbols_from_dest_or_src (*pinfo, A->g_src, A->g_dest, &A->g_symbol_table, &A->g_symbol_code);
}
//dw_printf ("DEBUG decode_aprs@end2 third_party=%d, symbol_table=%c, symbol_code=%c, *pinfo=%c\n", third_party, A->g_symbol_table, A->g_symbol_code, *pinfo);
}
} /* end decode_aprs */
void decode_aprs_print (decode_aprs_t *A) {
char stemp[500];
double absll;
char news;
int deg;
double min;
char s_lat[30];
char s_lon[30];
int n;
/*
* First line has:
* - packet type
* - object name
* - symbol
* - manufacturer/application
* - mic-e status
* - power/height/gain, range
*/
strlcpy (stemp, A->g_data_type_desc, sizeof(stemp));
//dw_printf ("DEBUG decode_aprs_print stemp1=%s\n", stemp);
if (strlen(A->g_name) > 0) {
strlcat (stemp, ", \"", sizeof(stemp));
strlcat (stemp, A->g_name, sizeof(stemp));
strlcat (stemp, "\"", sizeof(stemp));
}
//dw_printf ("DEBUG decode_aprs_print stemp2=%s\n", stemp);
//dw_printf ("DEBUG decode_aprs_print symbol_code=%c=0x%02x\n", A->g_symbol_code, A->g_symbol_code);
if (A->g_symbol_code != ' ') {
char symbol_description[100];
symbols_get_description (A->g_symbol_table, A->g_symbol_code, symbol_description, sizeof(symbol_description));
//dw_printf ("DEBUG decode_aprs_print symbol_description_description=%s\n", symbol_description);
strlcat (stemp, ", ", sizeof(stemp));
strlcat (stemp, symbol_description, sizeof(stemp));
}
//dw_printf ("DEBUG decode_aprs_print stemp3=%s mfr=%s\n", stemp, A->g_mfr);
if (strlen(A->g_mfr) > 0) {
if (strcmp(A->g_dest, "APRS") == 0) {
strlcat (stemp, "\nUse of \"APRS\" in the destination field is obsolete.", sizeof(stemp));
strlcat (stemp, " You can help to improve the quality of APRS signals.", sizeof(stemp));
strlcat (stemp, "\nTell the sender (", sizeof(stemp));
strlcat (stemp, A->g_src, sizeof(stemp));
strlcat (stemp, ") to use the proper product code from", sizeof(stemp));
strlcat (stemp, " http://www.aprs.org/aprs11/tocalls.txt", sizeof(stemp));
}
else {
strlcat (stemp, ", ", sizeof(stemp));
strlcat (stemp, A->g_mfr, sizeof(stemp));
}
}
//dw_printf ("DEBUG decode_aprs_print stemp4=%s\n", stemp);
if (strlen(A->g_mic_e_status) > 0) {
strlcat (stemp, ", ", sizeof(stemp));
strlcat (stemp, A->g_mic_e_status, sizeof(stemp));
}
//dw_printf ("DEBUG decode_aprs_print stemp5=%s\n", stemp);
if (A->g_power > 0) {
char phg[100];
/* Protocol spec doesn't mention whether this is dBd or dBi. */
/* Clarified later. */
/* http://eng.usna.navy.mil/~bruninga/aprs/aprs11.html */
/* "The Antenna Gain in the PHG format on page 28 is in dBi." */
snprintf (phg, sizeof(phg), ", %d W height=%d %ddBi %s", A->g_power, A->g_height, A->g_gain, A->g_directivity);
strlcat (stemp, phg, sizeof(stemp));
}
if (A->g_range > 0) {
char rng[100];
snprintf (rng, sizeof(rng), ", range=%.1f", A->g_range);
strlcat (stemp, rng, sizeof(stemp));
}
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
*/
// FIXME soften language about upper case.
if (strlen(A->g_maidenhead) > 0) {
if (A->g_lat == G_UNKNOWN && A->g_lon == G_UNKNOWN) {
ll_from_grid_square (A->g_maidenhead, &(A->g_lat), &(A->g_lon));
}
dw_printf("Grid square = %s, ", A->g_maidenhead);
}
strlcpy (stemp, "", sizeof(stemp));
if (A->g_lat != G_UNKNOWN || A->g_lon != G_UNKNOWN) {
// Have location but it is possible one part is invalid.
if (A->g_lat != G_UNKNOWN) {
if (A->g_lat >= 0) {
absll = A->g_lat;
news = 'N';
}
else {
absll = - A->g_lat;
news = 'S';
}
deg = (int) absll;
min = (absll - deg) * 60.0;
snprintf (s_lat, sizeof(s_lat), "%c %02d%s%07.4f", news, deg, CH_DEGREE, min);
}
else {
strlcpy (s_lat, "Invalid Latitude", sizeof(s_lat));
}
if (A->g_lon != G_UNKNOWN) {
if (A->g_lon >= 0) {
absll = A->g_lon;
news = 'E';
}
else {
absll = - A->g_lon;
news = 'W';
}
deg = (int) absll;
min = (absll - deg) * 60.0;
snprintf (s_lon, sizeof(s_lon), "%c %03d%s%07.4f", news, deg, CH_DEGREE, min);
}
else {
strlcpy (s_lon, "Invalid Longitude", sizeof(s_lon));
}
snprintf (stemp, sizeof(stemp), "%s, %s", s_lat, s_lon);
}
if (strlen(A->g_aprstt_loc) > 0) {
if (strlen(stemp) > 0) strlcat (stemp, ", ", sizeof(stemp));
strlcat (stemp, A->g_aprstt_loc, sizeof(stemp));
};
if (A->g_speed_mph != G_UNKNOWN) {
char spd[32];
if (strlen(stemp) > 0) strlcat (stemp, ", ", sizeof(stemp));
snprintf (spd, sizeof(spd), "%.0f km/h (%.0f MPH)", DW_MILES_TO_KM(A->g_speed_mph), A->g_speed_mph);
strlcat (stemp, spd, sizeof(stemp));
};
if (A->g_course != G_UNKNOWN) {
char cse[20];
if (strlen(stemp) > 0) strlcat (stemp, ", ", sizeof(stemp));
snprintf (cse, sizeof(cse), "course %.0f", A->g_course);
strlcat (stemp, cse, sizeof(stemp));
};
if (A->g_altitude_ft != G_UNKNOWN) {
char alt[32];
if (strlen(stemp) > 0) strlcat (stemp, ", ", sizeof(stemp));
snprintf (alt, sizeof(alt), "alt %.0f m (%.0f ft)", DW_FEET_TO_METERS(A->g_altitude_ft), A->g_altitude_ft);
strlcat (stemp, alt, sizeof(stemp));
};
if (A->g_freq != G_UNKNOWN) {
char ftemp[30];
snprintf (ftemp, sizeof(ftemp), ", %.3f MHz", A->g_freq);
strlcat (stemp, ftemp, sizeof(stemp));
}
if (A->g_offset != G_UNKNOWN) {
char ftemp[30];
if (A->g_offset % 1000 == 0) {
snprintf (ftemp, sizeof(ftemp), ", %+dM", A->g_offset/1000);
}
else {
snprintf (ftemp, sizeof(ftemp), ", %+dk", A->g_offset);
}
strlcat (stemp, ftemp, sizeof(stemp));
}
if (A->g_tone != G_UNKNOWN) {
if (A->g_tone == 0) {
strlcat (stemp, ", no PL", sizeof(stemp));
}
else {
char ftemp[30];
snprintf (ftemp, sizeof(ftemp), ", PL %.1f", A->g_tone);
strlcat (stemp, ftemp, sizeof(stemp));
}
}
if (A->g_dcs != G_UNKNOWN) {
char ftemp[30];
snprintf (ftemp, sizeof(ftemp), ", DCS %03o", A->g_dcs);
strlcat (stemp, ftemp, sizeof(stemp));
}
if (strlen (stemp) > 0) {
text_color_set(DW_COLOR_DECODED);
dw_printf("%s\n", stemp);
}
/*
* Finally, any weather and/or comment.
*
* 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(A->g_weather);
if (n >= 1 && A->g_weather[n-1] == '\n') {
A->g_weather[n-1] = '\0';
n--;
}
if (n >= 1 && A->g_weather[n-1] == '\r') {
A->g_weather[n-1] = '\0';
n--;
}
if (n > 0) {
ax25_safe_print (A->g_weather, -1, 0);
dw_printf("\n");
}
if (strlen(A->g_telemetry) > 0) {
ax25_safe_print (A->g_telemetry, -1, 0);
dw_printf("\n");
}
n = strlen(A->g_comment);
if (n >= 1 && A->g_comment[n-1] == '\n') {
A->g_comment[n-1] = '\0';
n--;
}
if (n >= 1 && A->g_comment[n-1] == '\r') {
A->g_comment[n-1] = '\0';
n--;
}
if (n > 0) {
int j;
ax25_safe_print (A->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 values 00-7F, ASCII, Unicode, and ISO Latin-1 are all the same.
// ISO Latin-1 adds 80-FF range with a few common symbols, such as degree, and
// letters, with diacritical marks, for many European languages.
// Unicode range 80-FF is called "Latin-1 Supplement." Exactly the same as ISO Latin-1.
// For UTF-8, an additional byte is inserted.
// Unicode UTF-8
// ------- -----
// 8x C2 8x Insert C2, keep original
// 9x C2 9x "
// Ax C2 Ax "
// Bx C2 Bx "
// Cx C3 8x Insert C3, subtract 40 from original
// Dx C3 9x "
// Ex C3 Ax "
// Fx C3 Bx "
//
// Can we use this knowledge to provide guidance on other ISO Latin-1 characters besides degree?
// Should we?
// Reference: https://www.fileformat.info/info/unicode/utf8test.htm
if ( ! A->g_quiet) {
for (j=0; j<n; j++) {
if ((unsigned char)(A->g_comment[j]) == 0xb0 && (j == 0 || ! (A->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 char)(A->g_comment[j]) == 0xf8 && (j == n-1 || (A->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: A->g_lat, A->g_lon, A->g_symbol_table, A->g_symbol_code, A->g_speed_mph, A->g_course, A->g_altitude_ft.
*
* 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 (decode_aprs_t *A, 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;
strlcpy (A->g_data_type_desc, "Position", sizeof(A->g_data_type_desc));
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 (A, &(p->pos));
if (A->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. */
strlcpy (A->g_data_type_desc, "Weather Report", sizeof(A->g_data_type_desc));
weather_data (A, p->comment, TRUE);
}
else {
/* Regular position report. */
data_extension_comment (A, p->comment);
}
}
else /* Compressed location. */
{
decode_compressed_position (A, &(q->cpos));
if (A->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. */
strlcpy (A->g_data_type_desc, "Weather Report", sizeof(A->g_data_type_desc));
weather_data (A, q->comment, FALSE);
}
else {
/* Regular position report. */
process_comment (A, 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: A->g_lat, A->g_lon, A->g_symbol_table, A->g_symbol_code, A->g_speed_mph, A->g_course, A->g_altitude_ft.
*
* 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 (decode_aprs_t *A, 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;
strlcpy (A->g_data_type_desc, "Position with time", sizeof(A->g_data_type_desc));
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 (A, p->time_stamp);
decode_position (A, &(p->pos));
if (A->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. */
strlcpy (A->g_data_type_desc, "Weather Report", sizeof(A->g_data_type_desc));
weather_data (A, p->comment, TRUE);
}
else {
/* Regular position report. */
data_extension_comment (A, p->comment);
}
}
else /* Compressed location. */
{
ts = get_timestamp (A, p->time_stamp);
decode_compressed_position (A, &(q->cpos));
if (A->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. */
strlcpy (A->g_data_type_desc, "Weather Report", sizeof(A->g_data_type_desc));
weather_data (A, q->comment, FALSE);
}
else {
/* Regular position report. */
process_comment (A, q->comment, -1);
}
}
(void)(ts); // suppress 'set but not used' warning.
}
/*------------------------------------------------------------------
*
* Function: aprs_raw_nmea
*
* Purpose: Decode "Raw NMEA Position Report"
*
* Inputs: info - Pointer to Information field.
* ilen - Information field length.
*
* Outputs: A-> ...
*
* 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
*