static double tissue_tolerance_calc(const struct dive *dive)
{
int ci = -1;
double tissue_inertgas_saturation, buehlmann_inertgas_a, buehlmann_inertgas_b;
double ret_tolerance_limit_ambient_pressure = 0.0;
double gf_high = buehlmann_config.gf_high;
double gf_low = buehlmann_config.gf_low;
double surface = get_surface_pressure_in_mbar(dive, TRUE) / 1000.0;
double lowest_ceiling;
for (ci = 0; ci < 16; ci++)
{
double tolerated;
tissue_inertgas_saturation = tissue_n2_sat[ci] + tissue_he_sat[ci];
buehlmann_inertgas_a = ((buehlmann_N2_a[ci] * tissue_n2_sat[ci]) + (buehlmann_He_a[ci] * tissue_he_sat[ci])) / tissue_inertgas_saturation;
buehlmann_inertgas_b = ((buehlmann_N2_b[ci] * tissue_n2_sat[ci]) + (buehlmann_He_b[ci] * tissue_he_sat[ci])) / tissue_inertgas_saturation;
/* tolerated = (tissue_inertgas_saturation - buehlmann_inertgas_a) * buehlmann_inertgas_b; */
#if !GF_LOW_AT_MAXDEPTH
lowest_ceiling = (buehlmann_inertgas_b * tissue_inertgas_saturation - gf_low * buehlmann_inertgas_a * buehlmann_inertgas_b) /
((1.0 - buehlmann_inertgas_b) * gf_low + buehlmann_inertgas_b);
if (lowest_ceiling > gf_low_pressure_this_dive)
gf_low_pressure_this_dive = lowest_ceiling;
#endif
tolerated = (-buehlmann_inertgas_a * buehlmann_inertgas_b * (gf_high * gf_low_pressure_this_dive - gf_low * surface) -
(1.0 - buehlmann_inertgas_b) * (gf_high - gf_low) * gf_low_pressure_this_dive * surface +
buehlmann_inertgas_b * (gf_low_pressure_this_dive - surface) * tissue_inertgas_saturation) /
(-buehlmann_inertgas_a * buehlmann_inertgas_b * (gf_high - gf_low) +
(1.0 - buehlmann_inertgas_b)*(gf_low * gf_low_pressure_this_dive - gf_high * surface) +
buehlmann_inertgas_b * (gf_low_pressure_this_dive - surface));
tolerated_by_tissue[ci] = tolerated;
if (tolerated > ret_tolerance_limit_ambient_pressure)
{
ci_pointing_to_guiding_tissue = ci;
ret_tolerance_limit_ambient_pressure = tolerated;
}
}
return ret_tolerance_limit_ambient_pressure;
}
/* Let's try to do some deco calculations.
*/
void calculate_deco_information(struct dive *dive, struct divecomputer *dc, struct plot_info *pi, bool print_mode)
{
int i, count_iteration = 0;
double surface_pressure = (dc->surface_pressure.mbar ? dc->surface_pressure.mbar : get_surface_pressure_in_mbar(dive, true)) / 1000.0;
int last_ndl_tts_calc_time = 0;
int first_ceiling = 0;
bool first_iteration = true;
int final_tts = 0 , time_clear_ceiling = 0, time_deep_ceiling = 0, deco_time = 0, prev_deco_time = 10000000;
char *cache_data_initial = NULL;
/* For VPM-B outside the planner, cache the initial deco state for CVA iterations */
if (prefs.deco_mode == VPMB && !in_planner())
cache_deco_state(&cache_data_initial);
/* For VPM-B outside the planner, iterate until deco time converges (usually one or two iterations after the initial)
* Set maximum number of iterations to 10 just in case */
while ((abs(prev_deco_time - deco_time) >= 30) && (count_iteration < 10)) {
for (i = 1; i < pi->nr; i++) {
struct plot_data *entry = pi->entry + i;
int j, t0 = (entry - 1)->sec, t1 = entry->sec;
int time_stepsize = 20;
entry->ambpressure = depth_to_bar(entry->depth, dive);
entry->gfline = MAX((double)prefs.gflow, (entry->ambpressure - surface_pressure) / (gf_low_pressure_this_dive - surface_pressure) *
(prefs.gflow - prefs.gfhigh) +
prefs.gfhigh) *
(100.0 - AMB_PERCENTAGE) / 100.0 + AMB_PERCENTAGE;
if (t0 > t1) {
fprintf(stderr, "non-monotonous dive stamps %d %d\n", t0, t1);
int xchg = t1;
t1 = t0;
t0 = xchg;
}
if (t0 != t1 && t1 - t0 < time_stepsize)
time_stepsize = t1 - t0;
for (j = t0 + time_stepsize; j <= t1; j += time_stepsize) {
int depth = interpolate(entry[-1].depth, entry[0].depth, j - t0, t1 - t0);
add_segment(depth_to_bar(depth, dive),
&dive->cylinder[entry->cylinderindex].gasmix, time_stepsize, entry->o2pressure.mbar, dive, entry->sac);
if ((t1 - j < time_stepsize) && (j < t1))
time_stepsize = t1 - j;
}
if (t0 == t1) {
entry->ceiling = (entry - 1)->ceiling;
} else {
/* Keep updating the VPM-B gradients until the start of the ascent phase of the dive. */
if (prefs.deco_mode == VPMB && !in_planner() && (entry - 1)->ceiling >= first_ceiling && first_iteration == true) {
nuclear_regeneration(t1);
vpmb_start_gradient();
/* For CVA calculations, start by guessing deco time = dive time remaining */
deco_time = pi->maxtime - t1;
vpmb_next_gradient(deco_time, surface_pressure / 1000.0);
}
entry->ceiling = deco_allowed_depth(tissue_tolerance_calc(dive, depth_to_bar(entry->depth, dive)), surface_pressure, dive, !prefs.calcceiling3m);
/* If using VPM-B outside the planner, take first_ceiling_pressure as the deepest ceiling */
if (prefs.deco_mode == VPMB && !in_planner()) {
if (entry->ceiling >= first_ceiling) {
time_deep_ceiling = t1;
first_ceiling = entry->ceiling;
first_ceiling_pressure.mbar = depth_to_mbar(first_ceiling, dive);
if (first_iteration) {
nuclear_regeneration(t1);
vpmb_start_gradient();
/* For CVA calculations, start by guessing deco time = dive time remaining */
deco_time = pi->maxtime - t1;
vpmb_next_gradient(deco_time, surface_pressure / 1000.0);
}
}
// Use the point where the ceiling clears as the end of deco phase for CVA calculations
if (entry->ceiling > 0)
time_clear_ceiling = 0;
else if (time_clear_ceiling == 0)
time_clear_ceiling = t1;
}
}
for (j = 0; j < 16; j++) {
double m_value = buehlmann_inertgas_a[j] + entry->ambpressure / buehlmann_inertgas_b[j];
entry->ceilings[j] = deco_allowed_depth(tolerated_by_tissue[j], surface_pressure, dive, 1);
entry->percentages[j] = tissue_inertgas_saturation[j] < entry->ambpressure ?
tissue_inertgas_saturation[j] / entry->ambpressure * AMB_PERCENTAGE :
AMB_PERCENTAGE + (tissue_inertgas_saturation[j] - entry->ambpressure) / (m_value - entry->ambpressure) * (100.0 - AMB_PERCENTAGE);
}
/* should we do more calculations?
* We don't for print-mode because this info doesn't show up there
* If the ceiling hasn't cleared by the last data point, we need tts for VPM-B CVA calculation
* It is not necessary to do these calculation on the first VPMB iteration, except for the last data point */
if ((prefs.calcndltts && !print_mode && (prefs.deco_mode != VPMB || in_planner() || !first_iteration)) ||
(prefs.deco_mode == VPMB && !in_planner() && i == pi->nr - 1)) {
/* only calculate ndl/tts on every 30 seconds */
if ((entry->sec - last_ndl_tts_calc_time) < 30 && i != pi->nr - 1) {
struct plot_data *prev_entry = (entry - 1);
entry->stoptime_calc = prev_entry->stoptime_calc;
entry->stopdepth_calc = prev_entry->stopdepth_calc;
entry->tts_calc = prev_entry->tts_calc;
entry->ndl_calc = prev_entry->ndl_calc;
continue;
}
last_ndl_tts_calc_time = entry->sec;
/* We are going to mess up deco state, so store it for later restore */
char *cache_data = NULL;
cache_deco_state(&cache_data);
calculate_ndl_tts(entry, dive, surface_pressure);
if (prefs.deco_mode == VPMB && !in_planner() && i == pi->nr - 1)
final_tts = entry->tts_calc;
/* Restore "real" deco state for next real time step */
restore_deco_state(cache_data);
free(cache_data);
}
}
if (prefs.deco_mode == VPMB && !in_planner()) {
prev_deco_time = deco_time;
// Do we need to update deco_time?
if (final_tts > 0)
deco_time = pi->maxtime + final_tts - time_deep_ceiling;
else if (time_clear_ceiling > 0)
deco_time = time_clear_ceiling - time_deep_ceiling;
vpmb_next_gradient(deco_time, surface_pressure / 1000.0);
final_tts = 0;
last_ndl_tts_calc_time = 0;
first_ceiling = 0;
first_iteration = false;
count_iteration ++;
restore_deco_state(cache_data_initial);
} else {
// With Buhlmann, or not in planner, iterating isn't needed. This makes the while condition false.
prev_deco_time = deco_time = 0;
}
}
free(cache_data_initial);
#if DECO_CALC_DEBUG & 1
dump_tissues();
#endif
}
