Support tank size information download from Atomic Aquatics Cobalt

This should really be done in libdivecomputer, but that can't happen until
the API there gets extended to support tank sizes. So for now with this
code we manually parse the raw dive data (if downloaded via
libdivecomputer from a Cobalt) and setup the tank size ourselves.

This had relatively limited testing so far.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

libdivecomputer.c

@@ -42,7 +42,70 @@ static dc_status_t create_parser(device_data_t *devdata, dc_parser_t **parser)
 	return dc_parser_new(parser, devdata->device);
 }
 
-static int parse_gasmixes(device_data_t *devdata, struct dive *dive, dc_parser_t *parser, int ngases)
+/* Atomics Aquatics Cobalt specific parsing of tank information
+ * realistically this REALLY needs to be done in libdivecomputer - but the
+ * current API doesn't even have the notion of tank size, so for now I do
+ * this here, but I need to work with Jef to make sure this gets added in
+ * the new libdivecomputer API */
+#define COBALT_HEADER 228
+struct atomics_gas_info {
+	uint8_t gas_nr;
+	uint8_t po2imit;
+	uint8_t tankspecmethod;	/* 1: CF@psi 2: CF@bar 3: wet vol in deciliter */
+	uint8_t gasmixtype;
+	uint8_t fo2;
+	uint8_t fhe;
+	uint16_t startpressure;	/* in psi */
+	uint16_t tanksize;	/* CF or dl */
+	uint16_t workingpressure;
+	uint16_t sensorid;
+	uint16_t endpressure;	/* in psi */
+	uint16_t totalconsumption;	/* in liters */
+};
+#define COBALT_CFATPSI 1
+#define COBALT_CFATBAR 2
+#define COBALT_WETINDL 3
+
+static void get_tanksize(device_data_t *devdata, const unsigned char *data, cylinder_t *cyl, int idx)
+{
+	/* I don't like this kind of match... I'd love to have an ID and
+	 * a firmware version or... something; and even better, just get
+	 * this from libdivecomputer */
+	if (!strcmp(devdata->vendor, "Atomic Aquatics") &&
+	    !strcmp(devdata->product, "Cobalt")) {
+		struct atomics_gas_info *atomics_gas_info;
+		double airvolume;
+		int mbar;
+
+		/* at least some quick sanity check to make sure this is the
+		 * right data */
+		if (*(uint32_t *)data != 0xFFFEFFFE) {
+			printf("incorrect header for Atomics dive\n");
+			return;
+		}
+		atomics_gas_info = (void*)(data + COBALT_HEADER);
+		switch (atomics_gas_info[idx].tankspecmethod) {
+		case COBALT_CFATPSI:
+			airvolume = cuft_to_l(atomics_gas_info[idx].tanksize) * 1000.0;
+			mbar = psi_to_mbar(atomics_gas_info[idx].workingpressure);
+			cyl[idx].type.size.mliter = airvolume / bar_to_atm(mbar / 1000.0) + 0.5;
+			cyl[idx].type.workingpressure.mbar = mbar;
+			break;
+		case COBALT_CFATBAR:
+			airvolume = cuft_to_l(atomics_gas_info[idx].tanksize) * 1000.0;
+			mbar = atomics_gas_info[idx].workingpressure * 1000;
+			cyl[idx].type.size.mliter = airvolume / bar_to_atm(mbar / 1000.0) + 0.5;
+			cyl[idx].type.workingpressure.mbar = mbar;
+			break;
+		case COBALT_WETINDL:
+			cyl[idx].type.size.mliter = atomics_gas_info[idx].tanksize * 100;
+			break;
+		}
+	}
+}
+
+static int parse_gasmixes(device_data_t *devdata, struct dive *dive, dc_parser_t *parser, int ngases,
+	const unsigned char *data)
 {
 	int i;
 
@@ -69,6 +132,8 @@ static int parse_gasmixes(device_data_t *devdata, struct dive *dive, dc_parser_t
 
 		dive->cylinder[i].gasmix.o2.permille = o2;
 		dive->cylinder[i].gasmix.he.permille = he;
+
+		get_tanksize(devdata, data, dive->cylinder, i);
 	}
 	return DC_STATUS_SUCCESS;
 }
@@ -407,7 +472,7 @@ static int dive_cb(const unsigned char *data, unsigned int size,
 	dive->salinity = salinity * 10000.0 + 0.5;
 #endif
 
-	rc = parse_gasmixes(devdata, dive, parser, ngases);
+	rc = parse_gasmixes(devdata, dive, parser, ngases, data);
 	if (rc != DC_STATUS_SUCCESS) {
 		dev_info(devdata, _("Error parsing the gas mix"));
 		dc_parser_destroy(parser);