Exclude surface intervals from sac rate calculation

[ext/subsurface.git] / divelist.c

diff --git a/divelist.c b/divelist.c
index 48a9ea99a5030fd679dd773190fa3405b388f263..a8afd3ac2e5aac5540bd0faef71d3863c33d8c4c 100644 (file)
--- a/divelist.c
+++ b/divelist.c
@@ -320,6 +320,7 @@ static double calculate_airuse(struct dive *dive)
 static int calculate_sac(struct dive *dive)
 {
        double airuse, pressure, sac;
+       int duration, i;
 
        airuse = calculate_airuse(dive);
        if (!airuse)
@@ -327,9 +328,25 @@ static int calculate_sac(struct dive *dive)
        if (!dive->duration.seconds)
                return 0;
 
+       /* find and eliminate long surface intervals */
+       duration = dive->duration.seconds;
+       for (i = 0; i < dive->samples; i++) {
+               if (dive->sample[i].depth.mm < 100) { /* less than 10cm */
+                       int end = i + 1;
+                       while (end < dive->samples && dive->sample[end].depth.mm < 100)
+                               end++;
+                       /* we only want the actual surface time during a dive */
+                       if (end < dive->samples) {
+                               end--;
+                               duration -= dive->sample[end].time.seconds -
+                                               dive->sample[i].time.seconds;
+                               i = end + 1;
+                       }
+               }
+       }
        /* Mean pressure in atm: 1 atm per 10m */
        pressure = 1 + (dive->meandepth.mm / 10000.0);
-       sac = airuse / pressure * 60 / dive->duration.seconds;
+       sac = airuse / pressure * 60 / duration;
 
        /* milliliters per minute.. */
        return sac * 1000;