static int calculate_sac(struct dive *dive)
{
double airuse, pressure, sac;
int duration, i;
airuse = calculate_airuse(dive);
if (!airuse)
return 0;
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 / duration;
/* milliliters per minute.. */
return sac * 1000;
}
static void get_sac(struct dive *dive, int *val)
{
double airuse, pressure, sac;
*val = 0;
airuse = calculate_airuse(dive);
if (!airuse)
return;
if (!dive->duration.seconds)
return;
/* Mean pressure in atm: 1 atm per 10m */
pressure = 1 + (dive->meandepth.mm / 10000.0);
sac = airuse / pressure * 60 / dive->duration.seconds;
/* milliliters per minute.. */
*val = sac * 1000;
}
