1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
/* calculate deco values
* based on Bühlmann ZHL-16b
* based on an implemention by heinrichs weikamp for the DR5
* the original file doesn't carry a license and is used here with
* the permission of Matthias Heinrichs
*
* The implementation below is (C) Dirk Hohndel 2012 and released under the GPLv2
*
* clear_deco() - call to initialize for a new deco calculation
* add_segment(pressure, gasmix) - add 1 second at the given pressure, breathing gasmix
* deco_allowed_depth(tissues_tolerance, surface_pressure, dive, smooth)
* - ceiling based on lead tissue, surface pressure, 3m increments or smooth
*/
#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).
double safety_dist_deco_stop;//! assumed distance to official decompression where decompression takes places.
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.
double gf_low_position_max; //! gf_low_position below surface_max_depth.
double gf_high_emergency; //! emergency gf factors
double gf_low_emergency; //! gradient factor low (at bottom/start of deco calculation).
};
struct buehlmann_config buehlmann_config = { 1.0, 1.01, 0.5, 3, 75.0, 35.0, 10.0, 30.0, 95.0, 95.0 };
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 DIST_FROM_3_MTR 0.28
#define PRESSURE_CHANGE_3M 0.3
#define TOLERANCE 0.02
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_position_this_dive;
int divetime;
static double actual_gradient_limit(const struct dive_data *data)
{
double pressure_diff, limit_at_position;
double gf_high = buehlmann_config.gf_high;
double gf_low = buehlmann_config.gf_low;
pressure_diff = data->pressure - data->surface;
if (pressure_diff > TOLERANCE) {
if (pressure_diff < gf_low_position_this_dive)
limit_at_position = gf_high - ((gf_high - gf_low) * pressure_diff / gf_low_position_this_dive);
else
limit_at_position = gf_low;
} else {
limit_at_position = gf_high;
}
return limit_at_position;
}
static double gradient_factor_calculation(const struct dive_data *data)
{
double tissue_inertgas_saturation;
tissue_inertgas_saturation = tissue_n2_sat[ci_pointing_to_guiding_tissue] +
tissue_he_sat[ci_pointing_to_guiding_tissue];
if (tissue_inertgas_saturation < data->pressure)
return 0.0;
else
return (tissue_inertgas_saturation - data->pressure) /
(tissue_inertgas_saturation - tissue_tolerated_ambient_pressure[ci_pointing_to_guiding_tissue]);
}
static double tissue_tolerance_calc(void)
{
int ci = -1;
double tissue_inertgas_saturation, buehlmann_inertgas_a, buehlmann_inertgas_b;
double ret_tolerance_limit_ambient_pressure = -1.0;
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 (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 a second at the given pressure and gas to the deco calculation */
double add_segment(double pressure, struct gasmix *gasmix)
{
int ci;
double ppn2 = (pressure - WV_PRESSURE) * (1000 - gasmix->o2.permille - gasmix->he.permille) / 1000.0;
double pphe = (pressure - WV_PRESSURE) * gasmix->he.permille / 1000.0;
divetime++;
/* right now we just do OC */
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];
}
return tissue_tolerance_calc();
}
void clear_deco()
{
int ci;
for (ci = 0; ci < 16; ci++) {
tissue_n2_sat[ci] = 0.0;
tissue_he_sat[ci] = 0.0;
tissue_tolerated_ambient_pressure[ci] = 0.0;
}
divetime = 0;
}
unsigned int deco_allowed_depth(double tissues_tolerance, double surface_pressure, struct dive *dive, gboolean smooth)
{
unsigned int depth, multiples_of_3m;
gboolean below_gradient_limit;
double new_gradient_factor;
double pressure_delta = tissues_tolerance - surface_pressure;
struct dive_data mydata;
if (pressure_delta > 0) {
if (!smooth) {
multiples_of_3m = (pressure_delta + DIST_FROM_3_MTR) / 0.3;
depth = 3000 * multiples_of_3m;
} else {
depth = rel_mbar_to_depth(pressure_delta * 1000, dive);
}
} else {
depth = 0;
}
mydata.pressure = surface_pressure + depth / 10000.0;
mydata.surface = surface_pressure;
new_gradient_factor = gradient_factor_calculation(&mydata);
below_gradient_limit = (new_gradient_factor < actual_gradient_limit(&mydata));
while(!below_gradient_limit)
{
mydata.pressure += PRESSURE_CHANGE_3M;
new_gradient_factor = gradient_factor_calculation(&mydata);
below_gradient_limit = (new_gradient_factor < actual_gradient_limit(&mydata));
}
return depth;
}
|
