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add minmea_checksum

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This commit is contained in:
Kosma Moczek 2014-09-11 18:02:29 +02:00
parent f9584757c2
commit ae62148805
3 changed files with 39 additions and 0 deletions
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15
minmea.c
View File

@ -26,6 +26,21 @@ static int hex2int(char c)
return -1;
}
uint8_t minmea_checksum(const char *sentence)
{
// Support senteces with or without the starting dollar sign.
if (*sentence == '$')
sentence++;
uint8_t checksum = 0x00;
// The optional checksum is an XOR of all bytes between "$" and "*".
while (*sentence && *sentence != '*')
checksum ^= *sentence++;
return checksum;
}
bool minmea_check(const char *sentence, bool strict)
{
uint8_t checksum = 0x00;

5
minmea.h
View File

@ -138,6 +138,11 @@ struct minmea_sentence_gsv {
struct minmea_sat_info sats[4];
};
/**
* Calculate raw sentence checksum. Does not check sentence integrity.
*/
uint8_t minmea_checksum(const char *sentence);
/**
* Check sentence validity and checksum. Returns true for valid sentences.
*/

19
tests.c
View File

@ -56,6 +56,21 @@ static const char *invalid_sentences[] = {
NULL,
};
START_TEST(test_minmea_checksum)
{
ck_assert_int_eq(minmea_checksum(""), 0x00);
ck_assert_int_eq(minmea_checksum("$"), 0x00);
ck_assert_int_eq(minmea_checksum("*"), 0x00);
ck_assert_int_eq(minmea_checksum("$*"), 0x00);
ck_assert_int_eq(minmea_checksum("$GPTXT,01,01,02,ANTSTATUS=INIT*25"), 0x25);
ck_assert_int_eq(minmea_checksum("$GPTXT,01,01,02,ANTSTATUS=INIT"), 0x25);
ck_assert_int_eq(minmea_checksum("GPTXT,01,01,02,ANTSTATUS=INIT*25"), 0x25);
ck_assert_int_eq(minmea_checksum("GPTXT,01,01,02,ANTSTATUS=INIT"), 0x25);
ck_assert_int_eq(minmea_checksum("$GPXTE,A,A,0.67,L,N*6F"), 0x6f);
ck_assert_int_eq(minmea_checksum("GPXTE,A,A,0.67,L,N*6f"), 0x6f);
}
END_TEST
START_TEST(test_minmea_check)
{
for (const char **sentence=valid_sentences_nochecksum; *sentence; sentence++) {
@ -913,6 +928,10 @@ static Suite *minmea_suite(void)
{
Suite *s = suite_create ("minmea");
TCase *tc_checksum = tcase_create("minmea_checksum");
tcase_add_test(tc_checksum, test_minmea_checksum);
suite_add_tcase(s, tc_checksum);
TCase *tc_check = tcase_create("minmea_check");
tcase_add_test(tc_check, test_minmea_check);
suite_add_tcase(s, tc_check);