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esp32_Adafruit_GPS
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parse checksum to * 

Parse the NMEA checksum based on the location of the asterisk, rather than the end of the string. Avoids problems if line ends with other than CRLF.
This commit is contained in:
sellensr 2019-04-15 11:51:40 -04:00
parent 8e17fcc9a9
commit 0f867b508a
1 changed files with 6 additions and 5 deletions
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11
Adafruit_GPS.cpp
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@ -55,13 +55,14 @@ boolean Adafruit_GPS::parse(char *nmea) {
// do checksum check // do checksum check
// first look if we even have one // first look if we even have one
if (nmea[strlen(nmea)-4] == '*') { char *ast = strchr(nmea,'*');
uint16_t sum = parseHex(nmea[strlen(nmea)-3]) * 16; if (ast != NULL) {
sum += parseHex(nmea[strlen(nmea)-2]); uint16_t sum = parseHex(*(ast+1)) * 16;
sum += parseHex(*(ast+2));
// check checksum // check checksum
for (uint8_t i=2; i < (strlen(nmea)-4); i++) { for (char *p = nmea+2; p < ast; p++) {
sum ^= nmea[i]; sum ^= *p;
} }
if (sum != 0) { if (sum != 0) {
// bad checksum :( // bad checksum :(