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authorJosé Bollo <jose.bollo@iot.bzh>2016-07-08 15:40:54 +0200
committerJosé Bollo <jose.bollo@iot.bzh>2016-07-08 15:40:54 +0200
commit558449a87d0fb36481e69b70e06beee6009e217c (patch)
treea50caa4082a8da062d74bba1dc9c2e4effbd2860 /src
parentf903fe0d4ad34abf14f04b51345d602a9c4dbaf0 (diff)
more comments
Change-Id: If4b079d38aa9ab66438e8470a8c3e06de5e5573f Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Diffstat (limited to 'src')
-rw-r--r--src/af-gps-binding.c186
1 files changed, 131 insertions, 55 deletions
diff --git a/src/af-gps-binding.c b/src/af-gps-binding.c
index c96ccf0..668a10f 100644
--- a/src/af-gps-binding.c
+++ b/src/af-gps-binding.c
@@ -40,6 +40,8 @@
#define METER_PER_SECOND_TO_KILOMETER_PER_HOUR 3.6 /* 3600 / 1000 */
#define METER_PER_SECOND_TO_MILE_PER_HOUR 2.236936292 /* 3600 / 1609.344 */
+#define DEFAULT_PERIOD 2000 /* 2 seconds */
+
/*
* references:
*
@@ -47,6 +49,7 @@
* http://www.gpsinformation.org/dale/nmea.htm
*/
+/* flags for recording what field is set */
struct flags {
unsigned time: 1;
unsigned latitude: 1;
@@ -56,6 +59,7 @@ struct flags {
unsigned track: 1;
};
+/* the gps data converted */
struct gps {
struct flags set;
@@ -67,36 +71,47 @@ struct gps {
double track;
};
+/*
+ * the type of position expected
+ *
+ * here, this type is mainly the selection of units
+ */
enum type {
- type_wgs84,
- type_dms_kmh,
- type_dms_mph,
- type_dms_kn,
+ type_wgs84, /* longitude, latitude, track: degre, altitude: m, speed: m/s */
+ type_dms_kmh, /* longitude, latitude: degre°minute'second.xxx"X, track: degre, altitude: m, speed: km/h */
+ type_dms_mph, /* longitude, latitude: degre°minute'second.xxx"X, track: degre, altitude: m, speed: mph */
+ type_dms_kn, /* longitude, latitude: degre°minute'second.xxx"X, track: degre, altitude: m, speed: kn */
type_COUNT,
type_DEFAULT = type_wgs84,
type_INVALID = -1
};
struct event;
-struct period;
+/*
+ * for each expected period
+ */
struct period {
- struct period *next;
- struct event *events;
- uint32_t period;
- uint32_t last;
+ struct period *next; /* link to the next other period */
+ struct event *events; /* events for the period */
+ uint32_t period; /* value of the period in ms */
+ uint32_t last; /* last update of the period */
};
+/*
+ * each generated event
+ */
struct event {
- struct event *next;
- struct event *byid;
- struct period *period;
- const char *name;
- struct afb_event event;
- enum type type;
- int id;
+ struct event *next; /* link for the same period */
+ const char *name; /* name of the event */
+ struct afb_event event; /* the event for the binder */
+ enum type type; /* the type of data expected */
+ int id; /* id of the event for unsubscribe */
};
+/*
+ * names of the types
+ */
static const char * const type_NAMES[type_COUNT] = {
"WGS84",
"DMS.km/h",
@@ -109,30 +124,45 @@ static const char * const type_NAMES[type_COUNT] = {
*/
const struct afb_binding_interface *afbitf;
-static struct gps frames[10];
-static int frameidx;
-static int newframes;
-
-static struct json_object *time_ms;
-static struct json_object *latitude_wgs;
-static struct json_object *longitude_wgs;
-static struct json_object *latitude_dms;
-static struct json_object *longitude_dms;
-static struct json_object *altitude_m;
-static struct json_object *speed_ms;
-static struct json_object *speed_kmh;
-static struct json_object *speed_mph;
-static struct json_object *speed_kn;
-static struct json_object *track_d;
-
-static struct json_object *positions[type_COUNT];
+/*
+ * records the raw frames
+ */
+static struct gps frames[10]; /* a short memory for further computation if needed */
+static int frameidx; /* index of the last frame (frames are in the reverse order) */
+static int newframes; /* boolean indication of wether new frames are availables */
-static struct period *periods;
-static struct event *events;
+/*
+ * records the JSON object for sending positions
+ */
+static struct json_object *time_ms; /* time as double in millisecond */
+static struct json_object *latitude_wgs; /* latitude as double in degree */
+static struct json_object *longitude_wgs; /* longitude as double in degree */
+static struct json_object *latitude_dms; /* latitude as string in d°m's.s"X */
+static struct json_object *longitude_dms; /* longitude as string in d°m's.s"X */
+static struct json_object *altitude_m; /* altitude as double in meter */
+static struct json_object *speed_ms; /* speed as double in m/s */
+static struct json_object *speed_kmh; /* speed as double in km/h */
+static struct json_object *speed_mph; /* speed as double in mph */
+static struct json_object *speed_kn; /* speed as double in kn */
+static struct json_object *track_d; /* heading track as double in degree */
+
+static struct json_object *positions[type_COUNT]; /* computed positions by type */
+
+/* head of the list of periods */
+static struct period *list_of_periods;
/* declare the connection routine */
static int nmea_connect();
+/***************************************************************************************/
+/***************************************************************************************/
+/** **/
+/** **/
+/** SECTION: FORMATING JSON POSITIONS **/
+/** **/
+/** **/
+/***************************************************************************************/
+/***************************************************************************************/
/*
* Creates the JSON representation for Degree Minute Second representation of coordinates
*/
@@ -288,15 +318,34 @@ static struct json_object *position(enum type type)
return json_object_get(result);
}
+/***************************************************************************************/
+/***************************************************************************************/
+/** **/
+/** **/
+/** SECTION: MANAGING EVENTS **/
+/** **/
+/** **/
+/***************************************************************************************/
+/***************************************************************************************/
/*
* get the event handler of given id
*/
static struct event *event_of_id(int id)
{
- struct event *r = events;
- while(r && r->id != id)
- r = r->byid;
- return r;
+ struct period *p;
+ struct event *e;
+
+ p = list_of_periods;
+ while(p != NULL) {
+ e = p->events;
+ p = p->next;
+ while(e != NULL) {
+ if (e->id == id)
+ return e;
+ e = e->next;
+ }
+ }
+ return NULL;
}
/*
@@ -305,20 +354,20 @@ static struct event *event_of_id(int id)
static struct event *event_get(enum type type, int period)
{
static int id;
- int mask;
+ int shift;
uint32_t perio;
struct period *p, **pp, *np;
struct event *e;
/* normalize the period */
period = period <= 100 ? 1 : period > 60000 ? 600 : (period / 100);
- mask = 31;
- while(period > (period & mask))
- mask <<= 1;
- perio = (uint32_t)(100 * (period & mask));
+ shift = 0;
+ while((period >> shift) > 31)
+ shift++;
+ perio = (uint32_t)(100 * (((period >> shift) & 31) << shift));
/* search for the period */
- pp = &periods;
+ pp = &list_of_periods;
p = *pp;
while(p != NULL && p->period < perio) {
pp = &p->next;
@@ -355,8 +404,6 @@ static struct event *event_get(enum type type, int period)
}
e->next = p->events;
- e->byid = events;
- e->period = p;
e->type = type;
do {
id++;
@@ -365,16 +412,18 @@ static struct event *event_get(enum type type, int period)
} while(event_of_id(id) != NULL);
e->id = id;
p->events = e;
- events = e;
}
return e;
}
+/*
+ * Sends the events if needed
+ */
static void event_send()
{
struct period *p, **pp;
- struct event *e, **pe, **peid;
+ struct event *e, **pe;
struct timeval tv;
uint32_t now;
@@ -387,7 +436,7 @@ static void event_send()
now = (uint32_t)(tv.tv_sec * 1000) + (uint32_t)(tv.tv_usec / 1000);
/* iterates over the periods */
- pp = &periods;
+ pp = &list_of_periods;
p = *pp;
while (p != NULL) {
if (p->events == NULL) {
@@ -407,10 +456,6 @@ static void event_send()
else {
/* no more listeners, free the event */
*pe = e->next;
- peid = &events;
- while (*peid != e)
- peid = &(*peid)->byid;
- *peid = e->byid;
afb_event_drop(e->event);
free(e);
}
@@ -423,6 +468,18 @@ static void event_send()
}
}
+/***************************************************************************************/
+/***************************************************************************************/
+/** **/
+/** **/
+/** SECTION: HANDLING NMEA SENTENCES **/
+/** **/
+/** **/
+/***************************************************************************************/
+/***************************************************************************************/
+/*
+ * interprets a nmea time
+ */
static int nmea_time(const char *text, uint32_t *result)
{
uint32_t x;
@@ -466,6 +523,9 @@ static int nmea_time(const char *text, uint32_t *result)
return 1;
}
+/*
+ * interprets a nmea angle having minutes
+ */
static int nmea_angle(const char *text, double *result)
{
uint32_t x = 0;
@@ -503,6 +563,10 @@ static int nmea_angle(const char *text, double *result)
return 1;
}
+/*
+ * creates a new position for the given optionnal fields
+ * returns 1 if correct or 0 if a format error exists
+ */
static int nmea_set(
const char *tim,
const char *lat, const char *latu,
@@ -596,6 +660,9 @@ static int nmea_set(
return 1;
}
+/*
+ * Splits the nmea sentences in its fields
+ */
static int nmea_split(char *s, char *fields[], int count)
{
int index = 0;
@@ -789,6 +856,15 @@ static int nmea_connect()
return rc;
}
+/***************************************************************************************/
+/***************************************************************************************/
+/** **/
+/** **/
+/** SECTION: BINDING VERBS IMPLEMENTATION **/
+/** **/
+/** **/
+/***************************************************************************************/
+/***************************************************************************************/
/*
* Returns the type corresponding to the given name
*/
@@ -836,7 +912,7 @@ static void subscribe(struct afb_req req)
if (get_type_for_req(req, &type)) {
period = afb_req_value(req, "period");
- event = event_get(type, period == NULL ? 2000 : atoi(period));
+ event = event_get(type, period == NULL ? DEFAULT_PERIOD : atoi(period));
if (event == NULL)
afb_req_fail(req, "out-of-memory", NULL);
else if (afb_req_subscribe(req, event->event) != 0)