Shearwater: Add time synchronisation.

Add time synchronisation for Shearwater dive computers.
This synchronises the local time, which is all that is supported by all
Shearwater models except for the Teric.
Time synchronisation including the time zone for the Teric still has to
be added.

Signed-off-by: Michael Keller <[email protected]>

src/shearwater_common.c

@@ -36,6 +36,11 @@
 #define ESC_END   0xDC
 #define ESC_ESC   0xDD
 
+// SIDs for CAN WDBI (Write Data By Identifier) as defined by ISO 14229-1
+// (the RDBI command is implemented in shearwater_common_identifier)
+#define CAN_WDBI_REQUEST_SID 0x2E
+#define CAN_WDBI_RESPONSE_SID 0x6E
+
 dc_status_t
 shearwater_common_setup (shearwater_common_device_t *device, dc_context_t *context, dc_iostream_t *iostream)
 {
@@ -548,3 +553,80 @@ shearwater_common_identifier (shearwater_common_device_t *device, dc_buffer_t *b
 
 	return rc;
 }
+
+
+dc_status_t shearwater_common_can_wdbi (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int id)
+{
+	dc_device_t *abstract = (dc_device_t *)device;
+
+	unsigned n = 0;
+	char request_header[] = {
+		CAN_WDBI_REQUEST_SID,
+		(id >> 8) & 0xFF,
+		id & 0xFF
+	};
+	if (!dc_buffer_prepend(buffer, request_header, sizeof(request_header))) {
+		ERROR(abstract->context, "Insufficient buffer space available.");
+		return DC_STATUS_NOMEMORY;
+	}
+
+	char response[SZ_PACKET];
+	dc_status_t rc = shearwater_common_transfer(device, dc_buffer_get_data(buffer), dc_buffer_get_size(buffer), response, sizeof(response), &n);
+	if (rc != DC_STATUS_SUCCESS) {
+		return rc;
+	}
+
+	// Verify the response.
+	if (n < 3 || response[0] != CAN_WDBI_RESPONSE_SID || response[1] != request_header[1] || response[2] != request_header[2]) {
+		ERROR(abstract->context, "Unexpected response packet.");
+
+		return DC_STATUS_PROTOCOL;
+	}
+
+	return rc;
+}
+
+
+dc_status_t shearwater_common_device_timesync(dc_device_t *abstract, const dc_datetime_t *datetime)
+{
+	shearwater_common_device_t *device = (shearwater_common_device_t *)abstract;
+
+	dc_datetime_t local_time;
+	memcpy(&local_time, datetime, sizeof(local_time));
+
+	// We need to supply a unix timestamp in _local_ time
+	local_time.timezone = DC_TIMEZONE_NONE;
+
+	dc_ticks_t unix_timestamp = dc_datetime_mktime(&local_time);
+	if (unix_timestamp == -1) {
+		ERROR(abstract->context, "Invalid date/time value specified.");
+
+		return DC_STATUS_INVALIDARGS;
+	}
+
+	char shearwater_timestamp[] = {
+		(unix_timestamp >> 24) & 0xFF,
+		(unix_timestamp >> 16) & 0xFF,
+		(unix_timestamp >> 8) & 0xFF,
+		unix_timestamp & 0xFF
+	};
+
+	dc_buffer_t *buffer = dc_buffer_new(WDBI_TIME_PACKET_SIZE);
+	if (buffer == NULL) {
+		ERROR(abstract->context, "Insufficient buffer space available.");
+		dc_buffer_free(buffer);
+
+		return DC_STATUS_NOMEMORY;
+	}
+
+	dc_buffer_append(buffer, shearwater_timestamp, 4);
+
+	dc_status_t rc = shearwater_common_can_wdbi(device, buffer, ID_TIME);
+	if (rc != DC_STATUS_SUCCESS) {
+		ERROR(abstract->context, "Failed to write the dive computer time.");
+	}
+
+	dc_buffer_free(buffer);
+
+	return rc;
+}

src/shearwater_common.h

@@ -34,6 +34,9 @@ extern "C" {
 #define ID_FIRMWARE  0x8011
 #define ID_LOGUPLOAD 0x8021
 #define ID_HARDWARE  0x8050
+#define ID_TIME      0x9030
+
+#define WDBI_TIME_PACKET_SIZE 7
 
 #define PREDATOR 2
 #define PETREL   3
@@ -67,6 +70,10 @@ shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buf
 dc_status_t
 shearwater_common_identifier (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int id);
 
+dc_status_t shearwater_common_can_wdbi (shearwater_common_device_t *device, dc_buffer_t *buffer, unsigned int id);
+
+dc_status_t shearwater_common_device_timesync(dc_device_t *abstract, const dc_datetime_t *datetime);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */

src/shearwater_petrel.c

@@ -44,6 +44,16 @@ typedef struct shearwater_petrel_device_t {
 	unsigned char fingerprint[4];
 } shearwater_petrel_device_t;
 
+
+static dc_status_t shearwater_petrel_device_timesync(dc_device_t *abstract, const dc_datetime_t *datetime)
+{
+	// The Teric will need a different implementation
+	// to properly support time zones
+
+	return shearwater_common_device_timesync(abstract, datetime);
+}
+
+
 static dc_status_t shearwater_petrel_device_set_fingerprint (dc_device_t *abstract, const unsigned char data[], unsigned int size);
 static dc_status_t shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback, void *userdata);
 static dc_status_t shearwater_petrel_device_close (dc_device_t *abstract);
@@ -56,7 +66,7 @@ static const dc_device_vtable_t shearwater_petrel_device_vtable = {
 	NULL, /* write */
 	NULL, /* dump */
 	shearwater_petrel_device_foreach, /* foreach */
-	NULL, /* timesync */
+	shearwater_petrel_device_timesync,
 	shearwater_petrel_device_close /* close */
 };
 

src/shearwater_predator.c

@@ -53,7 +53,7 @@ static const dc_device_vtable_t shearwater_predator_device_vtable = {
 	NULL, /* write */
 	shearwater_predator_device_dump, /* dump */
 	shearwater_predator_device_foreach, /* foreach */
-	NULL, /* timesync */
+	shearwater_common_device_timesync,
 	NULL /* close */
 };