[PATCH] Add a simple table-based otu-calculator
Anton Lundin
glance at acc.umu.se
Tue Apr 2 14:15:51 PDT 2013
For dives where divecomputers haven't provided us with a maxCNS, we
calculate our cns accumulated during that dive based on a simple table.
---
divelist.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 45 insertions(+), 1 deletion(-)
diff --git a/divelist.c b/divelist.c
index 198e2d6..1d888c0 100644
--- a/divelist.c
+++ b/divelist.c
@@ -712,7 +712,7 @@ static int active_o2(struct dive *dive, struct divecomputer *dc, duration_t time
return o2permille;
}
-/* calculate OTU for a dive - this only takes the first diveomputer into account */
+/* calculate OTU for a dive - this only takes the first divecomputer into account */
static int calculate_otu(struct dive *dive)
{
int i;
@@ -736,6 +736,48 @@ static int calculate_otu(struct dive *dive)
}
return otu + 0.5;
}
+/* calculate CNS for a dive - this only takes the first divecomputer into account */
+int const cns_table[][3] = {
+/* po2, Maximum Single Exposure, Maximum 24 hour Exposure */
+ {1600, 45 * 60, 150 * 60},
+ {1500, 120 * 60, 180 * 60},
+ {1400, 150 * 60, 180 * 60},
+ {1300, 180 * 60, 210 * 60},
+ {1200, 210 * 60, 240 * 60},
+ {1100, 240 * 60, 270 * 60},
+ {1000, 300 * 60, 300 * 60},
+ { 900, 360 * 60, 360 * 60},
+ { 800, 450 * 60, 450 * 60},
+ { 700, 570 * 60, 570 * 60},
+ { 600, 720 * 60, 720 * 60}
+};
+static int calculate_cns(struct dive *dive)
+{
+ int i, j;
+ double cns = 0.0;
+ struct divecomputer *dc = &dive->dc;
+
+ for (i = 1; i < dc->samples; i++) {
+ int t;
+ int po2;
+ struct sample *sample = dc->sample + i;
+ struct sample *psample = sample - 1;
+ t = sample->time.seconds - psample->time.seconds;
+ if (sample->po2) {
+ po2 = sample->po2;
+ } else {
+ int o2 = active_o2(dive, dc, sample->time);
+ po2 = o2 / 1000.0 * depth_to_mbar(sample->depth.mm, dive);
+ }
+ /* Find what table-row we should calculate % for */
+ for (j = 1; j < sizeof(cns_table)/(sizeof(int) * 3); j++)
+ if (po2 > cns_table[j][0])
+ break;
+ j--;
+ cns += ((double)t)/((double)cns_table[j][1]);
+ }
+ return cns * 100;
+}
/*
* Return air usage (in liters).
*/
@@ -895,6 +937,8 @@ void update_cylinder_related_info(struct dive *dive)
if (dive != NULL) {
dive->sac = calculate_sac(dive);
dive->otu = calculate_otu(dive);
+ if (dive->maxcns == 0)
+ dive->maxcns = calculate_cns(dive);
}
}
--
1.7.10.4
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