From 711ce8858382bbcfbfdc557165a0e13f98a28de9 Mon Sep 17 00:00:00 2001
From: Jef Driesen <jefdriesen@users.sourceforge.net>
Date: Wed, 21 Apr 2010 14:08:17 +0000
Subject: [PATCH] Add support for dives with a depth based sample interval.

Because the sample data contains a timestamp with a limited resolution
of only one minute, there can be consecutive samples with identical
timestamps. To deal with this situation, samples with identical
timestamps are distributed evenly inside the one minute interval. All
resulting non-integer timestamps are rounded to the nearest second.

For dives with a time based interval, the timestamps are now validated.
---
 src/oceanic_vtpro_parser.c | 66 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/oceanic_vtpro_parser.c b/src/oceanic_vtpro_parser.c
index dd1d3f5..3d0f7f5 100644
--- a/src/oceanic_vtpro_parser.c
+++ b/src/oceanic_vtpro_parser.c
@@ -149,7 +149,7 @@ oceanic_vtpro_parser_samples_foreach (parser_t *abstract, sample_callback_t call
 
 	unsigned int time = 0;
 	unsigned int interval = 0;
-	switch ((data[0x27] >> 4) & 0x03) {
+	switch ((data[0x27] >> 4) & 0x07) {
 	case 0:
 		interval = 2;
 		break;
@@ -162,8 +162,14 @@ oceanic_vtpro_parser_samples_foreach (parser_t *abstract, sample_callback_t call
 	case 3:
 		interval = 60;
 		break;
+	default:
+		interval = 0;
+		break;
 	}
 
+	// Initialize the state for the timestamp processing.
+	unsigned int timestamp = 0, count = 0, i = 0;
+
 	unsigned int offset = 5 * PAGESIZE / 2;
 	while (offset + PAGESIZE / 2 <= size - PAGESIZE) {
 		parser_sample_value_t sample = {0};
@@ -174,8 +180,64 @@ oceanic_vtpro_parser_samples_foreach (parser_t *abstract, sample_callback_t call
 			continue;
 		}
 
+		// Get the current timestamp.
+		unsigned int current = bcd2dec (data[offset + 1] & 0x0F) * 60 + bcd2dec (data[offset + 0]);
+		if (current < timestamp) {
+			WARNING ("Timestamp moved backwards.");
+			return PARSER_STATUS_ERROR;
+		}
+
+		if (current != timestamp || count == 0) {
+			// A sample with a new timestamp.
+			i = 0;
+			if (interval) {
+				// With a time based sample interval, the maximum number
+				// of samples for a single timestamp is always fixed.
+				count = 60 / interval;
+			} else {
+				// With a depth based sample interval, the exact number
+				// of samples for a single timestamp needs to be counted.
+				count = 1;
+				unsigned int idx = offset + PAGESIZE / 2 ;
+				while (idx + PAGESIZE / 2 <= size - PAGESIZE) {
+					// Ignore empty samples.
+					if (array_isequal (data + idx, PAGESIZE / 2, 0x00)) {
+						idx += PAGESIZE / 2;
+						continue;
+					}
+
+					unsigned int next = bcd2dec (data[idx + 1] & 0x0F) * 60 + bcd2dec (data[idx + 0]);
+					if (next != current)
+						break;
+
+					idx += PAGESIZE / 2;
+					count++;
+				}
+			}
+		} else {
+			// A sample with the same timestamp.
+			i++;
+		}
+
+		if (interval) {
+			if (current > timestamp + 1) {
+				WARNING ("Unexpected timestamp jump.");
+				return PARSER_STATUS_ERROR;
+			}
+			if (i >= count) {
+				WARNING ("Unexpected number of samples with the same timestamp.");
+				return PARSER_STATUS_ERROR;
+			}
+		}
+
+		// Store the current timestamp.
+		timestamp = current;
+
 		// Time.
-		time += interval;
+		if (interval)
+			time += interval;
+		else
+			time = timestamp * 60 + (i + 1) * 60.0 / count + 0.5;
 		sample.time = time;
 		if (callback) callback (SAMPLE_TYPE_TIME, sample, userdata);