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#ifndef DIVE_H
#define DIVE_H
/*
* Some silly typedefs to make our units very explicit.
*
* Also, the units are chosen so that values can be expressible as
* integers, so that we never have FP rounding issues. And they
* are small enough that converting to/from imperial units doesn't
* really matter.
*
* We also strive to make '0' a meaningless number saying "not
* initialized", since many values are things that may not have
* been reported (eg tank pressure or temperature from dive
* computers that don't support them). But sometimes -1 is an even
* more explicit way of saying "not there".
*
* Thus "millibar" for pressure, for example, or "millikelvin" for
* temperatures. Doing temperatures in celsius or fahrenheit would
* make for loss of precision when converting from one to the other,
* and using millikelvin is SI-like but also means that a temperature
* of '0' is clearly just a missing temperature or tank pressure.
*
* Also strive to use units that can not possibly be mistaken for a
* valid value in a "normal" system without conversion. If the max
* depth of a dive is '20000', you probably didn't convert from mm on
* output, or if the max depth gets reported as "0.2ft" it was either
* a really boring dive, or there was some missing input conversion,
* and a 60-ft dive got recorded as 60mm.
*
* Doing these as "structs containing value" means that we always
* have to explicitly write out those units in order to get at the
* actual value. So there is hopefully little fear of using a value
* in millikelvin as Fahrenheit by mistake.
*
* We don't actually use these all yet, so maybe they'll change, but
* I made a number of types as guidelines.
*/
typedef struct {
int seconds;
} duration_t;
typedef struct {
int mm;
} depth_t;
typedef struct {
int mbar;
} pressure_t;
typedef struct {
int mkelvin;
} temperature_t;
typedef struct {
int mliter;
} volume_t;
typedef struct {
int permille;
} fraction_t;
typedef struct {
int grams;
} weight_t;
typedef struct {
fraction_t o2;
fraction_t n2;
fraction_t he2;
} gasmix_t;
typedef struct {
volume_t size;
pressure_t pressure;
} tank_type_t;
static inline int to_feet(depth_t depth)
{
return depth.mm * 0.00328084 + 0.5;
}
static inline int to_C(temperature_t temp)
{
if (!temp.mkelvin)
return 0;
return (temp.mkelvin - 273150) / 1000;
}
static inline int to_PSI(pressure_t pressure)
{
return pressure.mbar * 0.0145037738 + 0.5;
}
struct sample {
duration_t time;
depth_t depth;
temperature_t temperature;
pressure_t tankpressure;
int tankindex;
};
struct dive {
time_t when;
depth_t maxdepth, meandepth;
duration_t duration, surfacetime;
depth_t visibility;
temperature_t airtemp, watertemp;
pressure_t beginning_pressure, end_pressure;
int samples;
struct sample sample[];
};
#endif /* DIVE_H */
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