646 lines
19 KiB
C
646 lines
19 KiB
C
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/*
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* Copyright © 2014 Kosma Moczek <kosma@cloudyourcar.com>
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* This program is free software. It comes without any warranty, to the extent
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* permitted by applicable law. You can redistribute it and/or modify it under
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* the terms of the Do What The Fuck You Want To Public License, Version 2, as
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* published by Sam Hocevar. See the COPYING file for more details.
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*/
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#include "minmea.h"
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <stdarg.h>
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#include <time.h>
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#define boolstr(s) ((s) ? "true" : "false")
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static int hex2int(char c)
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{
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if (c >= '0' && c <= '9')
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return c - '0';
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if (c >= 'A' && c <= 'F')
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return c - 'A' + 10;
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if (c >= 'a' && c <= 'f')
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return c - 'a' + 10;
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return -1;
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}
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uint8_t minmea_checksum(const char *sentence)
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{
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// Support senteces with or without the starting dollar sign.
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if (*sentence == '$')
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sentence++;
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uint8_t checksum = 0x00;
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// The optional checksum is an XOR of all bytes between "$" and "*".
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while (*sentence && *sentence != '*')
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checksum ^= *sentence++;
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return checksum;
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}
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bool minmea_check(const char *sentence, bool strict)
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{
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uint8_t checksum = 0x00;
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// Sequence length is limited.
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if (strlen(sentence) > MINMEA_MAX_LENGTH + 3)
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return false;
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// A valid sentence starts with "$".
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if (*sentence++ != '$')
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return false;
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// The optional checksum is an XOR of all bytes between "$" and "*".
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while (*sentence && *sentence != '*' && isprint((unsigned char) *sentence))
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checksum ^= *sentence++;
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// If checksum is present...
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if (*sentence == '*') {
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// Extract checksum.
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sentence++;
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int upper = hex2int(*sentence++);
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if (upper == -1)
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return false;
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int lower = hex2int(*sentence++);
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if (lower == -1)
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return false;
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int expected = upper << 4 | lower;
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// Check for checksum mismatch.
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if (checksum != expected)
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return false;
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} else if (strict) {
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// Discard non-checksummed frames in strict mode.
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return false;
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}
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// The only stuff allowed at this point is a newline.
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if (*sentence && strcmp(sentence, "\n") && strcmp(sentence, "\r\n"))
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return false;
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return true;
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}
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static inline bool minmea_isfield(char c) {
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return isprint((unsigned char) c) && c != ',' && c != '*';
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}
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bool minmea_scan(const char *sentence, const char *format, ...)
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{
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bool result = false;
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bool optional = false;
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va_list ap;
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va_start(ap, format);
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const char *field = sentence;
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#define next_field() \
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do { \
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/* Progress to the next field. */ \
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while (minmea_isfield(*sentence)) \
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sentence++; \
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/* Make sure there is a field there. */ \
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if (*sentence == ',') { \
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sentence++; \
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field = sentence; \
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} else { \
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field = NULL; \
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} \
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} while (0)
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while (*format) {
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char type = *format++;
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if (type == ';') {
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// All further fields are optional.
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optional = true;
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continue;
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}
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if (!field && !optional) {
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// Field requested but we ran out if input. Bail out.
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goto parse_error;
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}
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switch (type) {
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case 'c': { // Single character field (char).
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char value = '\0';
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if (field && minmea_isfield(*field))
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value = *field;
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*va_arg(ap, char *) = value;
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} break;
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case 'd': { // Single character direction field (int).
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int value = 0;
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if (field && minmea_isfield(*field)) {
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switch (*field) {
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case 'N':
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case 'E':
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value = 1;
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break;
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case 'S':
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case 'W':
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value = -1;
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break;
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default:
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goto parse_error;
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}
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}
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*va_arg(ap, int *) = value;
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} break;
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case 'f': { // Fractional value with scale (struct minmea_float).
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int sign = 0;
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int_least32_t value = -1;
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int_least32_t scale = 0;
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if (field) {
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while (minmea_isfield(*field)) {
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if (*field == '+' && !sign && value == -1) {
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sign = 1;
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} else if (*field == '-' && !sign && value == -1) {
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sign = -1;
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} else if (isdigit((unsigned char) *field)) {
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int digit = *field - '0';
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if (value == -1)
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value = 0;
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if (value > (INT_LEAST32_MAX-digit) / 10) {
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/* we ran out of bits, what do we do? */
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if (scale) {
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/* truncate extra precision */
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break;
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} else {
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/* integer overflow. bail out. */
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goto parse_error;
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}
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}
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value = (10 * value) + digit;
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if (scale)
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scale *= 10;
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} else if (*field == '.' && scale == 0) {
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scale = 1;
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} else if (*field == ' ') {
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/* Allow spaces at the start of the field. Not NMEA
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* conformant, but some modules do this. */
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if (sign != 0 || value != -1 || scale != 0)
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goto parse_error;
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} else {
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goto parse_error;
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}
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field++;
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}
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}
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if ((sign || scale) && value == -1)
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goto parse_error;
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if (value == -1) {
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/* No digits were scanned. */
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value = 0;
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scale = 0;
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} else if (scale == 0) {
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/* No decimal point. */
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scale = 1;
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}
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if (sign)
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value *= sign;
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*va_arg(ap, struct minmea_float *) = (struct minmea_float) {value, scale};
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} break;
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case 'i': { // Integer value, default 0 (int).
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int value = 0;
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if (field) {
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char *endptr;
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value = strtol(field, &endptr, 10);
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if (minmea_isfield(*endptr))
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goto parse_error;
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}
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*va_arg(ap, int *) = value;
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} break;
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case 's': { // String value (char *).
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char *buf = va_arg(ap, char *);
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if (field) {
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while (minmea_isfield(*field))
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*buf++ = *field++;
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}
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*buf = '\0';
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} break;
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case 't': { // NMEA talker+sentence identifier (char *).
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// This field is always mandatory.
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if (!field)
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goto parse_error;
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if (field[0] != '$')
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goto parse_error;
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for (int f=0; f<5; f++)
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if (!minmea_isfield(field[1+f]))
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goto parse_error;
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char *buf = va_arg(ap, char *);
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memcpy(buf, field+1, 5);
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buf[5] = '\0';
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} break;
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case 'D': { // Date (int, int, int), -1 if empty.
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struct minmea_date *date = va_arg(ap, struct minmea_date *);
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int d = -1, m = -1, y = -1;
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if (field && minmea_isfield(*field)) {
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// Always six digits.
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for (int f=0; f<6; f++)
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if (!isdigit((unsigned char) field[f]))
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goto parse_error;
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char dArr[] = {field[0], field[1], '\0'};
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char mArr[] = {field[2], field[3], '\0'};
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char yArr[] = {field[4], field[5], '\0'};
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d = strtol(dArr, NULL, 10);
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m = strtol(mArr, NULL, 10);
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y = strtol(yArr, NULL, 10);
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}
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date->day = d;
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date->month = m;
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date->year = y;
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} break;
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case 'T': { // Time (int, int, int, int), -1 if empty.
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struct minmea_time *time_ = va_arg(ap, struct minmea_time *);
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int h = -1, i = -1, s = -1, u = -1;
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if (field && minmea_isfield(*field)) {
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// Minimum required: integer time.
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for (int f=0; f<6; f++)
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if (!isdigit((unsigned char) field[f]))
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goto parse_error;
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char hArr[] = {field[0], field[1], '\0'};
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char iArr[] = {field[2], field[3], '\0'};
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char sArr[] = {field[4], field[5], '\0'};
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h = strtol(hArr, NULL, 10);
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i = strtol(iArr, NULL, 10);
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s = strtol(sArr, NULL, 10);
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field += 6;
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// Extra: fractional time. Saved as microseconds.
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if (*field++ == '.') {
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uint32_t value = 0;
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uint32_t scale = 1000000LU;
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while (isdigit((unsigned char) *field) && scale > 1) {
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value = (value * 10) + (*field++ - '0');
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scale /= 10;
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}
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u = value * scale;
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} else {
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u = 0;
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}
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}
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time_->hours = h;
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time_->minutes = i;
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time_->seconds = s;
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time_->microseconds = u;
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} break;
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case '_': { // Ignore the field.
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} break;
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default: { // Unknown.
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goto parse_error;
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}
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}
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next_field();
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}
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result = true;
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parse_error:
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va_end(ap);
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return result;
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}
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bool minmea_talker_id(char talker[3], const char *sentence)
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{
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char type[6];
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if (!minmea_scan(sentence, "t", type))
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return false;
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talker[0] = type[0];
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talker[1] = type[1];
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talker[2] = '\0';
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return true;
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}
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enum minmea_sentence_id minmea_sentence_id(const char *sentence, bool strict)
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{
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if (!minmea_check(sentence, strict))
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return MINMEA_INVALID;
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char type[6];
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if (!minmea_scan(sentence, "t", type))
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return MINMEA_INVALID;
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if (!strcmp(type+2, "RMC"))
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return MINMEA_SENTENCE_RMC;
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if (!strcmp(type+2, "GGA"))
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return MINMEA_SENTENCE_GGA;
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if (!strcmp(type+2, "GSA"))
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return MINMEA_SENTENCE_GSA;
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if (!strcmp(type+2, "GLL"))
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return MINMEA_SENTENCE_GLL;
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if (!strcmp(type+2, "GST"))
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return MINMEA_SENTENCE_GST;
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if (!strcmp(type+2, "GSV"))
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return MINMEA_SENTENCE_GSV;
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if (!strcmp(type+2, "VTG"))
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return MINMEA_SENTENCE_VTG;
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if (!strcmp(type+2, "ZDA"))
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return MINMEA_SENTENCE_ZDA;
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return MINMEA_UNKNOWN;
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}
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bool minmea_parse_rmc(struct minmea_sentence_rmc *frame, const char *sentence)
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{
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// $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62
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char type[6];
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char validity;
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int latitude_direction;
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int longitude_direction;
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int variation_direction;
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if (!minmea_scan(sentence, "tTcfdfdffDfd",
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type,
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&frame->time,
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&validity,
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&frame->latitude, &latitude_direction,
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&frame->longitude, &longitude_direction,
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&frame->speed,
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&frame->course,
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&frame->date,
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|
|
&frame->variation, &variation_direction))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "RMC"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
frame->valid = (validity == 'A');
|
||
|
|
frame->latitude.value *= latitude_direction;
|
||
|
|
frame->longitude.value *= longitude_direction;
|
||
|
|
frame->variation.value *= variation_direction;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_gga(struct minmea_sentence_gga *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
|
||
|
|
char type[6];
|
||
|
|
int latitude_direction;
|
||
|
|
int longitude_direction;
|
||
|
|
|
||
|
|
if (!minmea_scan(sentence, "tTfdfdiiffcfcf_",
|
||
|
|
type,
|
||
|
|
&frame->time,
|
||
|
|
&frame->latitude, &latitude_direction,
|
||
|
|
&frame->longitude, &longitude_direction,
|
||
|
|
&frame->fix_quality,
|
||
|
|
&frame->satellites_tracked,
|
||
|
|
&frame->hdop,
|
||
|
|
&frame->altitude, &frame->altitude_units,
|
||
|
|
&frame->height, &frame->height_units,
|
||
|
|
&frame->dgps_age))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "GGA"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
frame->latitude.value *= latitude_direction;
|
||
|
|
frame->longitude.value *= longitude_direction;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_gsa(struct minmea_sentence_gsa *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39
|
||
|
|
char type[6];
|
||
|
|
|
||
|
|
if (!minmea_scan(sentence, "tciiiiiiiiiiiiifff",
|
||
|
|
type,
|
||
|
|
&frame->mode,
|
||
|
|
&frame->fix_type,
|
||
|
|
&frame->sats[0],
|
||
|
|
&frame->sats[1],
|
||
|
|
&frame->sats[2],
|
||
|
|
&frame->sats[3],
|
||
|
|
&frame->sats[4],
|
||
|
|
&frame->sats[5],
|
||
|
|
&frame->sats[6],
|
||
|
|
&frame->sats[7],
|
||
|
|
&frame->sats[8],
|
||
|
|
&frame->sats[9],
|
||
|
|
&frame->sats[10],
|
||
|
|
&frame->sats[11],
|
||
|
|
&frame->pdop,
|
||
|
|
&frame->hdop,
|
||
|
|
&frame->vdop))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "GSA"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_gll(struct minmea_sentence_gll *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPGLL,3723.2475,N,12158.3416,W,161229.487,A,A*41$;
|
||
|
|
char type[6];
|
||
|
|
int latitude_direction;
|
||
|
|
int longitude_direction;
|
||
|
|
|
||
|
|
if (!minmea_scan(sentence, "tfdfdTc;c",
|
||
|
|
type,
|
||
|
|
&frame->latitude, &latitude_direction,
|
||
|
|
&frame->longitude, &longitude_direction,
|
||
|
|
&frame->time,
|
||
|
|
&frame->status,
|
||
|
|
&frame->mode))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "GLL"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
frame->latitude.value *= latitude_direction;
|
||
|
|
frame->longitude.value *= longitude_direction;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_gst(struct minmea_sentence_gst *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPGST,024603.00,3.2,6.6,4.7,47.3,5.8,5.6,22.0*58
|
||
|
|
char type[6];
|
||
|
|
|
||
|
|
if (!minmea_scan(sentence, "tTfffffff",
|
||
|
|
type,
|
||
|
|
&frame->time,
|
||
|
|
&frame->rms_deviation,
|
||
|
|
&frame->semi_major_deviation,
|
||
|
|
&frame->semi_minor_deviation,
|
||
|
|
&frame->semi_major_orientation,
|
||
|
|
&frame->latitude_error_deviation,
|
||
|
|
&frame->longitude_error_deviation,
|
||
|
|
&frame->altitude_error_deviation))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "GST"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_gsv(struct minmea_sentence_gsv *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPGSV,3,1,11,03,03,111,00,04,15,270,00,06,01,010,00,13,06,292,00*74
|
||
|
|
// $GPGSV,3,3,11,22,42,067,42,24,14,311,43,27,05,244,00,,,,*4D
|
||
|
|
// $GPGSV,4,2,11,08,51,203,30,09,45,215,28*75
|
||
|
|
// $GPGSV,4,4,13,39,31,170,27*40
|
||
|
|
// $GPGSV,4,4,13*7B
|
||
|
|
char type[6];
|
||
|
|
|
||
|
|
if (!minmea_scan(sentence, "tiii;iiiiiiiiiiiiiiii",
|
||
|
|
type,
|
||
|
|
&frame->total_msgs,
|
||
|
|
&frame->msg_nr,
|
||
|
|
&frame->total_sats,
|
||
|
|
&frame->sats[0].nr,
|
||
|
|
&frame->sats[0].elevation,
|
||
|
|
&frame->sats[0].azimuth,
|
||
|
|
&frame->sats[0].snr,
|
||
|
|
&frame->sats[1].nr,
|
||
|
|
&frame->sats[1].elevation,
|
||
|
|
&frame->sats[1].azimuth,
|
||
|
|
&frame->sats[1].snr,
|
||
|
|
&frame->sats[2].nr,
|
||
|
|
&frame->sats[2].elevation,
|
||
|
|
&frame->sats[2].azimuth,
|
||
|
|
&frame->sats[2].snr,
|
||
|
|
&frame->sats[3].nr,
|
||
|
|
&frame->sats[3].elevation,
|
||
|
|
&frame->sats[3].azimuth,
|
||
|
|
&frame->sats[3].snr
|
||
|
|
)) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
if (strcmp(type+2, "GSV"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_vtg(struct minmea_sentence_vtg *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPVTG,054.7,T,034.4,M,005.5,N,010.2,K*48
|
||
|
|
// $GPVTG,156.1,T,140.9,M,0.0,N,0.0,K*41
|
||
|
|
// $GPVTG,096.5,T,083.5,M,0.0,N,0.0,K,D*22
|
||
|
|
// $GPVTG,188.36,T,,M,0.820,N,1.519,K,A*3F
|
||
|
|
char type[6];
|
||
|
|
char c_true, c_magnetic, c_knots, c_kph, c_faa_mode;
|
||
|
|
|
||
|
|
if (!minmea_scan(sentence, "tfcfcfcfc;c",
|
||
|
|
type,
|
||
|
|
&frame->true_track_degrees,
|
||
|
|
&c_true,
|
||
|
|
&frame->magnetic_track_degrees,
|
||
|
|
&c_magnetic,
|
||
|
|
&frame->speed_knots,
|
||
|
|
&c_knots,
|
||
|
|
&frame->speed_kph,
|
||
|
|
&c_kph,
|
||
|
|
&c_faa_mode))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "VTG"))
|
||
|
|
return false;
|
||
|
|
// check chars
|
||
|
|
if (c_true != 'T' ||
|
||
|
|
c_magnetic != 'M' ||
|
||
|
|
c_knots != 'N' ||
|
||
|
|
c_kph != 'K')
|
||
|
|
return false;
|
||
|
|
frame->faa_mode = (enum minmea_faa_mode)c_faa_mode;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool minmea_parse_zda(struct minmea_sentence_zda *frame, const char *sentence)
|
||
|
|
{
|
||
|
|
// $GPZDA,201530.00,04,07,2002,00,00*60
|
||
|
|
char type[6];
|
||
|
|
|
||
|
|
if(!minmea_scan(sentence, "tTiiiii",
|
||
|
|
type,
|
||
|
|
&frame->time,
|
||
|
|
&frame->date.day,
|
||
|
|
&frame->date.month,
|
||
|
|
&frame->date.year,
|
||
|
|
&frame->hour_offset,
|
||
|
|
&frame->minute_offset))
|
||
|
|
return false;
|
||
|
|
if (strcmp(type+2, "ZDA"))
|
||
|
|
return false;
|
||
|
|
|
||
|
|
// check offsets
|
||
|
|
if (abs(frame->hour_offset) > 13 ||
|
||
|
|
frame->minute_offset > 59 ||
|
||
|
|
frame->minute_offset < 0)
|
||
|
|
return false;
|
||
|
|
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
int minmea_gettime(struct timespec *ts, const struct minmea_date *date, const struct minmea_time *time_)
|
||
|
|
{
|
||
|
|
if (date->year == -1 || time_->hours == -1)
|
||
|
|
return -1;
|
||
|
|
|
||
|
|
struct tm tm;
|
||
|
|
memset(&tm, 0, sizeof(tm));
|
||
|
|
if (date->year < 80) {
|
||
|
|
tm.tm_year = 2000 + date->year - 1900; // 2000-2079
|
||
|
|
} else if (date->year >= 1900) {
|
||
|
|
tm.tm_year = date->year - 1900; // 4 digit year, use directly
|
||
|
|
} else {
|
||
|
|
tm.tm_year = date->year; // 1980-1999
|
||
|
|
}
|
||
|
|
tm.tm_mon = date->month - 1;
|
||
|
|
tm.tm_mday = date->day;
|
||
|
|
tm.tm_hour = time_->hours;
|
||
|
|
tm.tm_min = time_->minutes;
|
||
|
|
tm.tm_sec = time_->seconds;
|
||
|
|
|
||
|
|
time_t timestamp = timegm(&tm); /* See README.md if your system lacks timegm(). */
|
||
|
|
if (timestamp != (time_t)-1) {
|
||
|
|
ts->tv_sec = timestamp;
|
||
|
|
ts->tv_nsec = time_->microseconds * 1000;
|
||
|
|
return 0;
|
||
|
|
} else {
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* vim: set ts=4 sw=4 et: */
|