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// SPDX-License-Identifier: GPL-2.0
#ifndef GAS_H
#define GAS_H
#include "divemode.h"
#include "units.h"
#ifdef __cplusplus
extern "C" {
#else
#include <stdbool.h>
#endif
enum gas_component { N2, HE, O2 };
// o2 == 0 && he == 0 -> air
// o2 < 0 -> invalid
struct gasmix {
fraction_t o2;
fraction_t he;
};
static const struct gasmix gasmix_invalid = { { -1 }, { -1 } };
static const struct gasmix gasmix_air = { { 0 }, { 0 } };
struct icd_data { // This structure provides communication between function isobaric_counterdiffusion() and the calling software.
int dN2; // The change in fraction (permille) of nitrogen during the change
int dHe; // The change in fraction (permille) of helium during the change
};
extern bool isobaric_counterdiffusion(struct gasmix oldgasmix, struct gasmix newgasmix, struct icd_data *results);
extern double gas_compressibility_factor(struct gasmix gas, double bar);
extern double isothermal_pressure(struct gasmix gas, double p1, int volume1, int volume2);
extern double gas_density(struct gasmix gas, int pressure);
extern int same_gasmix(struct gasmix a, struct gasmix b);
static inline int get_o2(struct gasmix mix)
{
return mix.o2.permille ?: O2_IN_AIR;
}
static inline int get_he(struct gasmix mix)
{
return mix.he.permille;
}
static inline int get_n2(struct gasmix mix)
{
return 1000 - get_o2(mix) - get_he(mix);
}
struct gas_pressures {
double o2, n2, he;
};
extern void sanitize_gasmix(struct gasmix *mix);
extern int gasmix_distance(struct gasmix a, struct gasmix b);
extern fraction_t get_gas_component_fraction(struct gasmix mix, enum gas_component component);
extern void fill_pressures(struct gas_pressures *pressures, double amb_pressure, struct gasmix mix, double po2, enum divemode_t dctype);
extern bool gasmix_is_air(struct gasmix gasmix);
#ifdef __cplusplus
}
#endif
#endif
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