Add support for the Mares Horizon

The Mares Horizon is a variant of the Mares Genius, with a few changes
to support SCR dives:

The dive header is slightly modified. There is an extra 8 byte field at
offset 0x18, which causes all later fields to have moved up with the
same amount. This difference is indicated in both the object minor
version (with a change from v0.0 to v0.1), and the logformat.

For the profile data, there is a new SDPT sample type which contains a
bit more information compared to the existing DPRS sample type. This
difference is indicated with a change in the object type (from 0 to 1).

The current implementation assumes a fixed order for the record types (a
DSTR record, a TISS record, zero or more DPRS/SDPT records with an AIRS
record every 4 sample, and finally a DEND record), and either only DPRS
or SDPT records but never a mixture of the two. If these assumptions
turns out to be incorrect, the implementation will need to be changed
significantly. Note that the assumption of the fixed order was already
present for the Genius.

Bluetooth support is currently disabled in the Horizon firmware, but
might be re-enabled in the future.

src/descriptor.c

@@ -294,6 +294,7 @@ static const dc_descriptor_t g_descriptors[] = {
 	{"Mares", "Quad Air",          DC_FAMILY_MARES_ICONHD , 0x23, DC_TRANSPORT_SERIAL | DC_TRANSPORT_BLE, dc_filter_mares},
 	{"Mares", "Smart Air",         DC_FAMILY_MARES_ICONHD , 0x24, DC_TRANSPORT_SERIAL | DC_TRANSPORT_BLE, dc_filter_mares},
 	{"Mares", "Quad",              DC_FAMILY_MARES_ICONHD , 0x29, DC_TRANSPORT_SERIAL | DC_TRANSPORT_BLE, dc_filter_mares},
+	{"Mares", "Horizon",           DC_FAMILY_MARES_ICONHD , 0x2C, DC_TRANSPORT_SERIAL, NULL},
 	/* Heinrichs Weikamp */
 	{"Heinrichs Weikamp", "OSTC",     DC_FAMILY_HW_OSTC, 0, DC_TRANSPORT_SERIAL, NULL},
 	{"Heinrichs Weikamp", "OSTC Mk2", DC_FAMILY_HW_OSTC, 1, DC_TRANSPORT_SERIAL, NULL},

src/mares_iconhd.c

@@ -49,6 +49,7 @@
 #define QUADAIR   0x23
 #define SMARTAIR  0x24
 #define QUAD      0x29
+#define HORIZON   0x2C
 
 #define MAXRETRIES 4
 
@@ -162,6 +163,7 @@ mares_iconhd_get_model (mares_iconhd_device_t *device)
 		{"Quad Air",    QUADAIR},
 		{"Smart Air",   SMARTAIR},
 		{"Quad",        QUAD},
+		{"Horizon",     HORIZON},
 	};
 
 	// Check the product name in the version packet against the list
@@ -566,6 +568,7 @@ mares_iconhd_device_open (dc_device_t **out, dc_context_t *context, dc_iostream_
 		device->packetsize = 256;
 		break;
 	case GENIUS:
+	case HORIZON:
 		device->layout = &mares_genius_layout;
 		device->packetsize = 4096;
 		device->fingerprint_size = 4;
@@ -958,7 +961,7 @@ mares_iconhd_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback,
 	devinfo.serial = array_uint32_le (serial);
 	device_event_emit (abstract, DC_EVENT_DEVINFO, &devinfo);
 
-	if (device->model == GENIUS) {
+	if (device->model == GENIUS || device->model == HORIZON) {
 		return mares_iconhd_device_foreach_object (abstract, callback, userdata);
 	} else {
 		return mares_iconhd_device_foreach_raw (abstract, callback, userdata);