subsurface/deco.c
Linus Torvalds b6c9301e58 Move more dive computer filled data to the divecomputer structure
This moves the fields 'duration', 'surfacetime', 'maxdepth',
'meandepth', 'airtemp', 'watertemp', 'salinity' and 'surface_pressure'
to the per-divecomputer data structure.  They are filled in by the dive
computer, and normally not edited.

NOTE! All actual *use* of this data was then changed from dive->field to
dive->dc.field programmatically with a shell-script and sed, and the
result then edited for details.  So while the XML save and restore code
has been updated, all the displaying etc will currently always just show
the first dive computer entry.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
2013-01-23 12:55:33 -08:00

281 lines
11 KiB
C

/* calculate deco values
* based on Bühlmann ZHL-16b
* based on an implemention by heinrichs weikamp for the DR5
* the original file was given to Subsurface under the GPLv2
* by Matthias Heinrichs
*
* The implementation below is a fairly complete rewrite since then
* (C) Robert C. Helling 2013 and released under the GPLv2
*
* add_segment() - add <seconds> at the given pressure, breathing gasmix
* deco_allowed_depth() - ceiling based on lead tissue, surface pressure, 3m increments or smooth
* set_gf() - set Buehlmann gradient factors
* clear_deco()
* cache_deco_state()
* restore_deco_state()
* dump_tissues()
*/
#include <math.h>
#include <string.h>
#include "dive.h"
//! Option structure for Buehlmann decompression.
struct buehlmann_config {
double satmult; //! safety at inert gas accumulation as percentage of effect (more than 100).
double desatmult; //! safety at inert gas depletion as percentage of effect (less than 100).
int last_deco_stop_in_mtr; //! depth of last_deco_stop.
double gf_high; //! gradient factor high (at surface).
double gf_low; //! gradient factor low (at bottom/start of deco calculation).
double gf_low_position_min; //! gf_low_position below surface_min_shallow.
};
struct buehlmann_config buehlmann_config = { 1.0, 1.01, 0, 0.75, 0.35, 2.0 };
struct dive_data {
double pressure; //! pesent ambient pressure
double surface; //! pressure at water surface
struct gasmix *gasmix; //! current selected gas
};
const double buehlmann_N2_a[] = {1.1696, 1.0, 0.8618, 0.7562,
0.62, 0.5043, 0.441, 0.4,
0.375, 0.35, 0.3295, 0.3065,
0.2835, 0.261, 0.248, 0.2327};
const double buehlmann_N2_b[] = {0.5578, 0.6514, 0.7222, 0.7825,
0.8126, 0.8434, 0.8693, 0.8910,
0.9092, 0.9222, 0.9319, 0.9403,
0.9477, 0.9544, 0.9602, 0.9653};
const double buehlmann_N2_t_halflife[] = {5.0, 8.0, 12.5, 18.5,
27.0, 38.3, 54.3, 77.0,
109.0, 146.0, 187.0, 239.0,
305.0, 390.0, 498.0, 635.0};
const double buehlmann_N2_factor_expositon_one_second[] = {
2.30782347297664E-003, 1.44301447809736E-003, 9.23769302935806E-004, 6.24261986779007E-004,
4.27777107246730E-004, 3.01585140931371E-004, 2.12729727268379E-004, 1.50020603047807E-004,
1.05980191127841E-004, 7.91232600646508E-005, 6.17759153688224E-005, 4.83354552742732E-005,
3.78761777920511E-005, 2.96212356654113E-005, 2.31974277413727E-005, 1.81926738960225E-005};
const double buehlmann_He_a[] = { 1.6189, 1.383 , 1.1919, 1.0458,
0.922 , 0.8205, 0.7305, 0.6502,
0.595 , 0.5545, 0.5333, 0.5189,
0.5181, 0.5176, 0.5172, 0.5119};
const double buehlmann_He_b[] = {0.4770, 0.5747, 0.6527, 0.7223,
0.7582, 0.7957, 0.8279, 0.8553,
0.8757, 0.8903, 0.8997, 0.9073,
0.9122, 0.9171, 0.9217, 0.9267};
const double buehlmann_He_t_halflife[] = {1.88, 3.02, 4.72, 6.99,
10.21, 14.48, 20.53, 29.11,
41.20, 55.19, 70.69, 90.34,
115.29, 147.42, 188.24, 240.03};
const double buehlmann_He_factor_expositon_one_second[] = {
6.12608039419837E-003, 3.81800836683133E-003, 2.44456078654209E-003, 1.65134647076792E-003,
1.13084424730725E-003, 7.97503165599123E-004, 5.62552521860549E-004, 3.96776399429366E-004,
2.80360036664540E-004, 2.09299583354805E-004, 1.63410794820518E-004, 1.27869320250551E-004,
1.00198406028040E-004, 7.83611475491108E-005, 6.13689891868496E-005, 4.81280465299827E-005};
#define WV_PRESSURE 0.0627 /* water vapor pressure */
#define DECO_STOPS_MULTIPLIER_MM 3000.0
#define GF_LOW_AT_MAXDEPTH 0
double tissue_n2_sat[16];
double tissue_he_sat[16];
double tissue_tolerated_ambient_pressure[16];
int ci_pointing_to_guiding_tissue;
double gf_low_pressure_this_dive;
#define TISSUE_ARRAY_SZ sizeof(tissue_n2_sat)
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 = dive->dc.surface_pressure.mbar / 1000.0;
double lowest_ceiling;
for (ci = 0; ci < 16; ci++)
{
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;
/* tissue_tolerated_ambient_pressure[ci] = (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
tissue_tolerated_ambient_pressure[ci] = (-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));
if (tissue_tolerated_ambient_pressure[ci] > ret_tolerance_limit_ambient_pressure)
{
ci_pointing_to_guiding_tissue = ci;
ret_tolerance_limit_ambient_pressure = tissue_tolerated_ambient_pressure[ci];
}
}
return ret_tolerance_limit_ambient_pressure;
}
/* add period_in_seconds at the given pressure and gas to the deco calculation */
double add_segment(double pressure, struct gasmix *gasmix, int period_in_seconds, double ccpo2, const struct dive *dive)
{
int ci;
int fo2 = gasmix->o2.permille ? gasmix->o2.permille : O2_IN_AIR;
double ppn2 = (pressure - WV_PRESSURE) * (1000 - fo2 - gasmix->he.permille) / 1000.0;
double pphe = (pressure - WV_PRESSURE) * gasmix->he.permille / 1000.0;
#if GF_LOW_AT_MAXDEPTH
if (pressure > gf_low_pressure_this_dive)
gf_low_pressure_this_dive = pressure;
#endif
if (ccpo2 > 0.0) { /* CC */
double rel_o2_amb, f_dilutent;
rel_o2_amb = ccpo2 / pressure;
f_dilutent = (1 - rel_o2_amb) / (1 - fo2 / 1000.0);
if (f_dilutent < 0) { /* setpoint is higher than ambient pressure -> pure O2 */
ppn2 = 0.0;
pphe = 0.0;
} else if (f_dilutent < 1.0) {
ppn2 *= f_dilutent;
pphe *= f_dilutent;
}
}
if (period_in_seconds == 1) { /* one second interval during dive */
for (ci = 0; ci < 16; ci++) {
if (ppn2 - tissue_n2_sat[ci] > 0)
tissue_n2_sat[ci] += buehlmann_config.satmult * (ppn2 - tissue_n2_sat[ci]) *
buehlmann_N2_factor_expositon_one_second[ci];
else
tissue_n2_sat[ci] += buehlmann_config.desatmult * (ppn2 - tissue_n2_sat[ci]) *
buehlmann_N2_factor_expositon_one_second[ci];
if (pphe - tissue_he_sat[ci] > 0)
tissue_he_sat[ci] += buehlmann_config.satmult * (pphe - tissue_he_sat[ci]) *
buehlmann_He_factor_expositon_one_second[ci];
else
tissue_he_sat[ci] += buehlmann_config.desatmult * (pphe - tissue_he_sat[ci]) *
buehlmann_He_factor_expositon_one_second[ci];
}
} else { /* all other durations */
for (ci = 0; ci < 16; ci++)
{
if (ppn2 - tissue_n2_sat[ci] > 0)
tissue_n2_sat[ci] += buehlmann_config.satmult * (ppn2 - tissue_n2_sat[ci]) *
(1 - pow(2.0,(- period_in_seconds / (buehlmann_N2_t_halflife[ci] * 60))));
else
tissue_n2_sat[ci] += buehlmann_config.desatmult * (ppn2 - tissue_n2_sat[ci]) *
(1 - pow(2.0,(- period_in_seconds / (buehlmann_N2_t_halflife[ci] * 60))));
if (pphe - tissue_he_sat[ci] > 0)
tissue_he_sat[ci] += buehlmann_config.satmult * (pphe - tissue_he_sat[ci]) *
(1 - pow(2.0,(- period_in_seconds / (buehlmann_He_t_halflife[ci] * 60))));
else
tissue_he_sat[ci] += buehlmann_config.desatmult * (pphe - tissue_he_sat[ci]) *
(1 - pow(2.0,(- period_in_seconds / (buehlmann_He_t_halflife[ci] * 60))));
}
}
return tissue_tolerance_calc(dive);
}
void dump_tissues()
{
int ci;
printf("N2 tissues:");
for (ci = 0; ci < 16; ci++)
printf(" %6.3e", tissue_n2_sat[ci]);
printf("\nHe tissues:");
for (ci = 0; ci < 16; ci++)
printf(" %6.3e", tissue_he_sat[ci]);
printf("\n");
}
void clear_deco(double surface_pressure)
{
int ci;
for (ci = 0; ci < 16; ci++) {
tissue_n2_sat[ci] = (surface_pressure - WV_PRESSURE) * N2_IN_AIR / 1000;
tissue_he_sat[ci] = 0.0;
tissue_tolerated_ambient_pressure[ci] = 0.0;
}
gf_low_pressure_this_dive = surface_pressure + buehlmann_config.gf_low_position_min;
}
void cache_deco_state(double tissue_tolerance, char **cached_datap)
{
char *data = *cached_datap;
if (!data) {
data = malloc(3 * TISSUE_ARRAY_SZ + 2 * sizeof(double) + sizeof(int));
*cached_datap = data;
}
memcpy(data, tissue_n2_sat, TISSUE_ARRAY_SZ);
data += TISSUE_ARRAY_SZ;
memcpy(data, tissue_he_sat, TISSUE_ARRAY_SZ);
data += TISSUE_ARRAY_SZ;
memcpy(data, tissue_tolerated_ambient_pressure, TISSUE_ARRAY_SZ);
data += TISSUE_ARRAY_SZ;
memcpy(data, &gf_low_pressure_this_dive, sizeof(double));
data += sizeof(double);
memcpy(data, &tissue_tolerance, sizeof(double));
data += sizeof(double);
memcpy(data, &ci_pointing_to_guiding_tissue, sizeof(int));
}
double restore_deco_state(char *data)
{
double tissue_tolerance;
memcpy(tissue_n2_sat, data, TISSUE_ARRAY_SZ);
data += TISSUE_ARRAY_SZ;
memcpy(tissue_he_sat, data, TISSUE_ARRAY_SZ);
data += TISSUE_ARRAY_SZ;
memcpy(tissue_tolerated_ambient_pressure, data, TISSUE_ARRAY_SZ);
data += TISSUE_ARRAY_SZ;
memcpy(&gf_low_pressure_this_dive, data, sizeof(double));
data += sizeof(double);
memcpy(&tissue_tolerance, data, sizeof(double));
data += sizeof(double);
memcpy(&ci_pointing_to_guiding_tissue, data, sizeof(int));
return tissue_tolerance;
}
unsigned int deco_allowed_depth(double tissues_tolerance, double surface_pressure, struct dive *dive, gboolean smooth)
{
unsigned int depth;
double pressure_delta;
/* Avoid negative depths */
pressure_delta = tissues_tolerance > surface_pressure ? tissues_tolerance - surface_pressure : 0.0;
depth = rel_mbar_to_depth(pressure_delta * 1000, dive);
if(!smooth)
depth = ceil(depth / DECO_STOPS_MULTIPLIER_MM) * DECO_STOPS_MULTIPLIER_MM;
if(depth > 0 && depth < buehlmann_config.last_deco_stop_in_mtr * 1000)
depth = buehlmann_config.last_deco_stop_in_mtr * 1000;
return depth;
}
void set_gf(double gflow, double gfhigh)
{
if (gflow != -1.0)
buehlmann_config.gf_low = gflow;
if (gfhigh != -1.0)
buehlmann_config.gf_high = gfhigh;
}