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
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
|
/* 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, 3, 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 N2_IN_AIR 0.7902
#define DECO_STOPS_MULTIPLIER_MM 3000.0
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->surface_pressure.mbar / 1000.0;
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; */
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 : 209;
double ppn2 = (pressure - WV_PRESSURE) * (1000 - fo2 - gasmix->he.permille) / 1000.0;
double pphe = (pressure - WV_PRESSURE) * gasmix->he.permille / 1000.0;
if (pressure > gf_low_pressure_this_dive)
gf_low_pressure_this_dive = pressure;
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;
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;
}
|
