minmea: don't include talker id in sentence type.

This is a backwards-incompatible change that I knew I'd have to
introduce sooner or later. Which means now.

Long story short: when I first started writing this library, I wanted to
make things simpler by treating the entire talker+sentence as one big
ID. Of course, this is an oversimplification, as there are different
talkers out there.

Turns out they're more common than I initially thought. I just came
across a module (read: I had one soldered to my board by our crazy
hardware guy) that spits out GPRMC, GLRMC or GNRMC depending on where it
got the data. I could have kludged around this, but here's this change,
for the purity of code.

Fortunately, we're the only users of this codebase as far as I know, so
no real harm is done - but it's a lesson to design my interfaces right
from the very start so I don't have to break compatibility and write
apologetic messages later on.

README.md

@@ -53,10 +53,10 @@ The library doesn't perform this conversion automatically for the following reas
     char line[MINMEA_MAX_LENGTH];
     while (fgets(line, sizeof(line), stdin) != NULL) {
         printf("%s", line);
-        switch (minmea_type(line)) {
-            case MINMEA_GPRMC: {
-                struct minmea_gprmc frame;
-                if (minmea_parse_gprmc(&frame, line)) {
+        switch (minmea_sentence_id(line)) {
+            case MINMEA_SENTENCE_RMC: {
+                struct minmea_sentence_rmc frame;
+                if (minmea_parse_rmc(&frame, line)) {
                     printf("+++ raw coordinates and speed: (%d/%d,%d/%d) %d/%d\n",
                             frame.latitude, frame.latitude_scale,
                             frame.longitude, frame.longitude_scale,
@@ -72,15 +72,12 @@ The library doesn't perform this conversion automatically for the following reas
                 }
             } break;
 
-            case MINMEA_GPGGA: {
-                struct minmea_gpgga frame;
-                if (minmea_parse_gpgga(&frame, line)) {
+            case MINMEA_SENTENCE_GGA: {
+                struct minmea_sentence_gga frame;
+                if (minmea_parse_gga(&frame, line)) {
                     printf("$GPGGA: fix quality: %d\n", frame.fix_quality);
                 }
             } break;
-
-            default: {
-            } break;
         }
     }
 ```

example.c

@@ -17,10 +17,10 @@ int main()
     char line[MINMEA_MAX_LENGTH];
     while (fgets(line, sizeof(line), stdin) != NULL) {
         printf("%s", line);
-        switch (minmea_type(line)) {
-            case MINMEA_GPRMC: {
-                struct minmea_gprmc frame;
-                if (minmea_parse_gprmc(&frame, line)) {
+        switch (minmea_sentence_id(line)) {
+            case MINMEA_SENTENCE_RMC: {
+                struct minmea_sentence_rmc frame;
+                if (minmea_parse_rmc(&frame, line)) {
                     printf("+++ raw coordinates and speed: (%d/%d,%d/%d) %d/%d\n",
                             frame.latitude, frame.latitude_scale,
                             frame.longitude, frame.longitude_scale,
@@ -36,9 +36,9 @@ int main()
                 }
             } break;
 
-            case MINMEA_GPGGA: {
-                struct minmea_gpgga frame;
-                if (minmea_parse_gpgga(&frame, line)) {
+            case MINMEA_SENTENCE_GGA: {
+                struct minmea_sentence_gga frame;
+                if (minmea_parse_gga(&frame, line)) {
                     printf("$GPGGA: fix quality: %d\n", frame.fix_quality);
                 }
             } break;

minmea.c

@@ -175,7 +175,7 @@ bool minmea_scan(const char *sentence, const char *format, ...)
                 *buf = '\0';
             } break;
 
-            case 't': { // NMEA talker+sequence identifier (char *).
+            case 't': { // NMEA talker+sentence identifier (char *).
                 if (field[0] != '$')
                     goto end;
                 for (int i=0; i<5; i++)
@@ -259,7 +259,7 @@ end:
     return result;
 }
 
-enum minmea_type minmea_type(const char *sentence)
+enum minmea_sentence_id minmea_sentence_id(const char *sentence)
 {
     if (!minmea_check(sentence))
         return MINMEA_INVALID;
@@ -268,17 +268,17 @@ enum minmea_type minmea_type(const char *sentence)
     if (!minmea_scan(sentence, "t", type))
         return MINMEA_INVALID;
 
-    if (!strcmp(type, "GPRMC"))
-        return MINMEA_GPRMC;
-    if (!strcmp(type, "GPGGA"))
-        return MINMEA_GPGGA;
-    if (!strcmp(type, "GPGSA"))
-        return MINMEA_GPGSA;
+    if (!strcmp(type+2, "RMC"))
+        return MINMEA_SENTENCE_RMC;
+    if (!strcmp(type+2, "GGA"))
+        return MINMEA_SENTENCE_GGA;
+    if (!strcmp(type+2, "GSA"))
+        return MINMEA_SENTENCE_GSA;
 
     return MINMEA_UNKNOWN;
 }
 
-bool minmea_parse_gprmc(struct minmea_gprmc *frame, const char *sentence)
+bool minmea_parse_rmc(struct minmea_sentence_rmc *frame, const char *sentence)
 {
     // $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62
     char type[6];
@@ -297,7 +297,7 @@ bool minmea_parse_gprmc(struct minmea_gprmc *frame, const char *sentence)
             &frame->date,
             &frame->variation, &frame->variation_scale, &variation_direction))
         return false;
-    if (strcmp(type, "GPRMC"))
+    if (strcmp(type+2, "RMC"))
         return false;
 
     frame->valid = (validity == 'A');
@@ -308,7 +308,7 @@ bool minmea_parse_gprmc(struct minmea_gprmc *frame, const char *sentence)
     return true;
 }
 
-bool minmea_parse_gpgga(struct minmea_gpgga *frame, const char *sentence)
+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];
@@ -327,7 +327,7 @@ bool minmea_parse_gpgga(struct minmea_gpgga *frame, const char *sentence)
             &frame->height, &frame->height_scale, &frame->height_units,
             &frame->dgps_age))
         return false;
-    if (strcmp(type, "GPGGA"))
+    if (strcmp(type+2, "GGA"))
         return false;
 
     frame->latitude *= latitude_direction;
@@ -336,7 +336,7 @@ bool minmea_parse_gpgga(struct minmea_gpgga *frame, const char *sentence)
     return true;
 }
 
-bool minmea_parse_gpgsa(struct minmea_gpgsa *frame, const char *sentence)
+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];
@@ -366,7 +366,7 @@ bool minmea_parse_gpgsa(struct minmea_gpgsa *frame, const char *sentence)
             )){
         return false;
     }
-    if (strcmp(type, "GPGSA"))
+    if (strcmp(type+2, "GSA"))
         return false;
 
     return true;

minmea.h

@@ -23,12 +23,12 @@ extern "C" {
 
 #define MINMEA_MAX_LENGTH 80
 
-enum minmea_type {
+enum minmea_sentence_id {
     MINMEA_INVALID = -1,
     MINMEA_UNKNOWN = 0,
-    MINMEA_GPRMC,
-    MINMEA_GPGGA,
-    MINMEA_GPGSA,
+    MINMEA_SENTENCE_RMC,
+    MINMEA_SENTENCE_GGA,
+    MINMEA_SENTENCE_GSA,
 };
 
 struct minmea_date {
@@ -44,7 +44,7 @@ struct minmea_time {
     int microseconds;
 };
 
-struct minmea_gprmc {
+struct minmea_sentence_rmc {
     struct minmea_time time;
     bool valid;
     int latitude, latitude_scale;
@@ -55,7 +55,7 @@ struct minmea_gprmc {
     int variation, variation_scale;
 };
 
-struct minmea_gpgga {
+struct minmea_sentence_gga {
     struct minmea_time time;
     int latitude, latitude_scale;
     int longitude, longitude_scale;
@@ -67,18 +67,18 @@ struct minmea_gpgga {
     int dgps_age;
 };
 
-enum minmea_gpgsa_mode {
+enum minmea_gsa_mode {
     MINMEA_GPGSA_MODE_AUTO = 'A',
     MINMEA_GPGSA_MODE_FORCED = 'M',
 };
 
-enum minmea_gpgsa_fix_type {
+enum minmea_gsa_fix_type {
     MINMEA_GPGSA_FIX_NONE = 1,
     MINMEA_GPGSA_FIX_2D = 2,
     MINMEA_GPGSA_FIX_3D = 3,
 };
 
-struct minmea_gpgsa {
+struct minmea_sentence_gsa {
     char mode;
     int fix_type;
     int sats[12];
@@ -88,14 +88,14 @@ struct minmea_gpgsa {
 };
 
 /**
- * Check sequence validity and checksum. Returns true for valid sequences.
+ * Check sentence validity and checksum. Returns true for valid sentences.
  */
 bool minmea_check(const char *sentence);
 
 /**
- * Determine sequence type.
+ * Determine sentence identifier.
  */
-enum minmea_type minmea_type(const char *sequence);
+enum minmea_sentence_id minmea_sentence_id(const char *sentence);
 
 /**
  * Scanf-like processor for NMEA sentences. Supports the following formats:
@@ -111,11 +111,11 @@ enum minmea_type minmea_type(const char *sequence);
 bool minmea_scan(const char *sentence, const char *format, ...);
 
 /*
- * Parse a specific type of frame. Return true on success.
+ * Parse a specific type of sentence. Return true on success.
  */
-bool minmea_parse_gprmc(struct minmea_gprmc *frame, const char *sentence);
-bool minmea_parse_gpgga(struct minmea_gpgga *frame, const char *sentence);
-bool minmea_parse_gpgsa(struct minmea_gpgsa *frame, const char *sentence);
+bool minmea_parse_rmc(struct minmea_sentence_rmc *frame, const char *sentence);
+bool minmea_parse_gga(struct minmea_sentence_gga *frame, const char *sentence);
+bool minmea_parse_gsa(struct minmea_sentence_gsa *frame, const char *sentence);
 
 /**
  * Convert GPS UTC date/time representation to a UNIX timestamp.

tests.c

@@ -284,11 +284,11 @@ START_TEST(test_minmea_scan_complex2)
 }
 END_TEST
 
-START_TEST(test_minmea_parse_gprmc1)
+START_TEST(test_minmea_parse_rmc1)
 {
     const char *sentence = "$GPRMC,081836.75,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E";
-    struct minmea_gprmc frame = {};
-    struct minmea_gprmc expected = {
+    struct minmea_sentence_rmc frame = {};
+    struct minmea_sentence_rmc expected = {
         .time = { 8, 18, 36, 750000 },
         .valid = true,
         .latitude = -375165,
@@ -304,16 +304,16 @@ START_TEST(test_minmea_parse_gprmc1)
         .variation_scale = 10,
     };
     ck_assert(minmea_check(sentence) == true);
-    ck_assert(minmea_parse_gprmc(&frame, sentence) == true);
+    ck_assert(minmea_parse_rmc(&frame, sentence) == true);
     ck_assert(!memcmp(&frame, &expected, sizeof(frame)));
 }
 END_TEST
 
-START_TEST(test_minmea_parse_gprmc2)
+START_TEST(test_minmea_parse_rmc2)
 {
     const char *sentence = "$GPRMC,,A,3751.65,N,14507.36,W,,,,,";
-    struct minmea_gprmc frame = {};
-    struct minmea_gprmc expected = {
+    struct minmea_sentence_rmc frame = {};
+    struct minmea_sentence_rmc expected = {
         .time = { -1, -1, -1, -1 },
         .valid = true,
         .latitude = 375165,
@@ -323,16 +323,16 @@ START_TEST(test_minmea_parse_gprmc2)
         .date = { -1, -1, -1 },
     };
     ck_assert(minmea_check(sentence) == true);
-    ck_assert(minmea_parse_gprmc(&frame, sentence) == true);
+    ck_assert(minmea_parse_rmc(&frame, sentence) == true);
     ck_assert(!memcmp(&frame, &expected, sizeof(frame)));
 }
 END_TEST
 
-START_TEST(test_minmea_parse_gpgga1)
+START_TEST(test_minmea_parse_gga1)
 {
     const char *sentence = "$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47";
-    struct minmea_gpgga frame = {};
-    struct minmea_gpgga expected = {
+    struct minmea_sentence_gga frame = {};
+    struct minmea_sentence_gga expected = {
         .time = { 12, 35, 19, 0 },
         .latitude = 4807038,
         .latitude_scale = 1000,
@@ -351,16 +351,16 @@ START_TEST(test_minmea_parse_gpgga1)
         .dgps_age = 0,
     };
     ck_assert(minmea_check(sentence) == true);
-    ck_assert(minmea_parse_gpgga(&frame, sentence) == true);
+    ck_assert(minmea_parse_gga(&frame, sentence) == true);
     ck_assert(!memcmp(&frame, &expected, sizeof(frame)));
 }
 END_TEST
 
-START_TEST(test_minmea_parse_gpgsa1)
+START_TEST(test_minmea_parse_gsa1)
 {
     const char *sentence = "$GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39";
-    struct minmea_gpgsa frame = {};
-    struct minmea_gpgsa expected = {
+    struct minmea_sentence_gsa frame = {};
+    struct minmea_sentence_gsa expected = {
         .mode = MINMEA_GPGSA_MODE_AUTO,
         .fix_type = MINMEA_GPGSA_FIX_3D,
         .sats = { 4, 5, 0, 9, 12, 0, 0, 24, 0, 0, 0, 0 },
@@ -372,7 +372,7 @@ START_TEST(test_minmea_parse_gpgsa1)
         .vdop_scale = 10
     };
     ck_assert(minmea_check(sentence) == true);
-    ck_assert(minmea_parse_gpgsa(&frame, sentence) == true);
+    ck_assert(minmea_parse_gsa(&frame, sentence) == true);
     ck_assert(!memcmp(&frame, &expected, sizeof(frame)));
 }
 END_TEST
@@ -387,20 +387,20 @@ START_TEST(test_minmea_usage1)
     };
 
     for (const char **sentence=sentences; *sentence; sentence++) {
-        switch (minmea_type(*sentence)) {
-            case MINMEA_GPRMC: {
-                struct minmea_gprmc frame;
-                ck_assert(minmea_parse_gprmc(&frame, *sentence) == true);
+        switch (minmea_sentence_id(*sentence)) {
+            case MINMEA_SENTENCE_RMC: {
+                struct minmea_sentence_rmc frame;
+                ck_assert(minmea_parse_rmc(&frame, *sentence) == true);
             } break;
             
-            case MINMEA_GPGGA: {
-                struct minmea_gpgga frame;
-                ck_assert(minmea_parse_gpgga(&frame, *sentence) == true);
+            case MINMEA_SENTENCE_GGA: {
+                struct minmea_sentence_gga frame;
+                ck_assert(minmea_parse_gga(&frame, *sentence) == true);
             } break;
             
-            case MINMEA_GPGSA: {
-                struct minmea_gpgsa frame;
-                ck_assert(minmea_parse_gpgsa(&frame, *sentence) == true);
+            case MINMEA_SENTENCE_GSA: {
+                struct minmea_sentence_gsa frame;
+                ck_assert(minmea_parse_gsa(&frame, *sentence) == true);
             } break;
 
 
@@ -486,10 +486,10 @@ Suite *minmea_suite(void)
     suite_add_tcase(s, tc_scan);
   
     TCase *tc_parse = tcase_create("minmea_parse");
-    tcase_add_test(tc_parse, test_minmea_parse_gprmc1);
-    tcase_add_test(tc_parse, test_minmea_parse_gprmc2);
-    tcase_add_test(tc_parse, test_minmea_parse_gpgga1);
-    tcase_add_test(tc_parse, test_minmea_parse_gpgsa1);
+    tcase_add_test(tc_parse, test_minmea_parse_rmc1);
+    tcase_add_test(tc_parse, test_minmea_parse_rmc2);
+    tcase_add_test(tc_parse, test_minmea_parse_gga1);
+    tcase_add_test(tc_parse, test_minmea_parse_gsa1);
     suite_add_tcase(s, tc_parse);
 
     TCase *tc_usage = tcase_create("minmea_usage");