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Helper function for partial pressure calculation

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This patch introduces a new structure holding partial pressures (doubles in bar) for
all three gases and a helper function to compute them from gasmix (which holds fractions)
and ambient pressure. Currentlty this works for OC and CCR, to be extended later to PSCR.

Currently the dive_comp_type argument is unused.

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
This commit is contained in:
Robert C. Helling 2014-09-15 14:55:20 +02:00 • committed by Dirk Hohndel
parent ae6b0468b1
commit d6abb739d9
8 changed files with 61 additions and 60 deletions
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23
dive.c
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@ -1454,6 +1454,29 @@ int gasmix_distance(const struct gasmix *a, const struct gasmix *b)
return delta_he + delta_o2;
}
/* Compute partial gas pressures in bar from gasmix and ambient pressures, possibly for OC or CCR, to be extended to PSCT */
extern void fill_pressures(struct gas_pressures *pressures, const double amb_pressure, const struct gasmix *mix, double po2, const enum dive_comp_type type)
{
if (po2) {
/* we have an O₂ partial pressure in the sample - so this
* is likely a CC dive... use that instead of the value
* from the cylinder info */
if (po2 >= amb_pressure || get_o2(mix) == 1000) {
pressures->o2 = amb_pressure;
pressures->he = 0;
pressures->n2 = 0;
} else {
pressures->he = (amb_pressure - pressures->o2) * (double)get_he(mix) / (1000 - get_o2(mix));
pressures->n2 = amb_pressure - pressures->o2 - pressures->he;
}
} else {
pressures->o2 = get_o2(mix) / 1000.0 * amb_pressure;
pressures->he = get_he(mix) / 1000.0 * amb_pressure;
pressures->n2 = (1000 - get_o2(mix) - get_he(mix)) / 1000.0 * amb_pressure;
}
}
static int find_cylinder_match(cylinder_t *cyl, cylinder_t array[], unsigned int used)
{
int i;