Further cleanup of pressure and volume conversions

I'm amazed at how many spots we were doing conversions - some of them
subtly different than others.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

diff --git a/dive.h b/dive.h
index fe4515ee6a26ea5b20a6b0572a823ed864a0d80f..783d640a08c4d8e298ecb5e3f349f58837acf859 100644 (file)
--- a/dive.h
+++ b/dive.h
@@ -91,9 +91,19 @@ extern double get_depth_units(unsigned int mm, int *frac, const char **units);
 extern double get_volume_units(unsigned int mm, int *frac, const char **units);
 extern double get_temp_units(unsigned int mm, const char **units);
 
+static inline double bar_to_atm(double bar)
+{
+       return bar / 1.01325;
+}
+
 static inline double ml_to_cuft(int ml)
 {
-       return ml / 28317.0;
+       return ml / 28316.8466;
+}
+
+static inline double cuft_to_ml(double cuft)
+{
+       return cuft * 28.3168466;
 }
 
 static inline double mm_to_feet(int mm)
@@ -137,6 +147,10 @@ static inline int to_K(temperature_t temp)
        return (temp.mkelvin + 499)/1000;
 }
 
+static inline double psi_to_bar(double psi)
+{
+       return psi / 14.5037738;
+}
 static inline int to_PSI(pressure_t pressure)
 {
        return pressure.mbar * 0.0145037738 + 0.5;

diff --git a/equipment.c b/equipment.c
index 12f39ae3f7c8bedab61ca1a91fa47c2c080f9a4e..64a05d5b024d3500ffbc6ff666cd3726d3ce99aa 100644 (file)
--- a/equipment.c
+++ b/equipment.c
@@ -49,18 +49,19 @@ struct cylinder_widget {
        GtkWidget *o2, *gasmix_button;
 };
 
+/* we want bar - so let's not use our unit functions */
 static int convert_pressure(int mbar, double *p)
 {
        int decimals = 1;
        double pressure;
 
-       pressure = mbar / 1000.0;
-       if (mbar) {
-               if (output_units.pressure == PSI) {
-                       pressure *= 14.5037738; /* Bar to PSI */
-                       decimals = 0;
-               }
+       if (output_units.pressure == PSI) {
+               pressure = mbar_to_PSI(mbar);
+               decimals = 0;
+       } else {
+               pressure = mbar / 1000.0;
        }
+
        *p = pressure;
        return decimals;
 }
@@ -70,17 +71,18 @@ static int convert_volume_pressure(int ml, int mbar, double *v, double *p)
        int decimals = 1;
        double volume, pressure;
 
-       volume = ml / 1000.0;
-       pressure = mbar / 1000.0;
        if (mbar) {
                if (output_units.volume == CUFT) {
-                       volume /= 28.3168466;   /* Liters to cuft */
-                       volume *= pressure / 1.01325;
-               }
+                       volume = ml_to_cuft(ml);
+                       volume *= bar_to_atm(mbar / 1000.0);
+               } else
+                       volume = ml / 1000.0;
+
                if (output_units.pressure == PSI) {
-                       pressure *= 14.5037738; /* Bar to PSI */
+                       pressure = mbar_to_PSI(mbar);
                        decimals = 0;
-               }
+               } else
+                       pressure = mbar / 1000.0;
        }
        *v = volume;
        *p = pressure;
@@ -352,14 +354,14 @@ static void fill_cylinder_info(struct cylinder_widget *cylinder, cylinder_t *cyl
        int mbar, ml;
 
        if (output_units.pressure == PSI) {
-               pressure /= 14.5037738;
-               start /= 14.5037738;
-               end /= 14.5037738;
+               pressure = psi_to_bar(pressure);
+               start = psi_to_bar(start);
+               end = psi_to_bar(end);
        }
 
        if (pressure && output_units.volume == CUFT) {
-               volume *= 28.3168466;   /* CUFT to liter */
-               volume /= pressure / 1.01325;
+               volume = cuft_to_ml(volume);
+               volume /= bar_to_atm(pressure);
        }
 
        ml = volume * 1000 + 0.5;
@@ -461,9 +463,9 @@ static void fill_tank_list(GtkListStore *store)
 
                /* Is it in cuft and psi? */
                if (psi) {
-                       double bar = 0.0689475729 * psi;
-                       double airvolume = 28316.8466 * size;
-                       double atm = bar / 1.01325;
+                       double bar = psi_to_bar(psi);
+                       double airvolume = cuft_to_ml(size);
+                       double atm = bar_to_atm(bar);
 
                        ml = airvolume / atm + 0.5;
                        mbar = bar*1000 + 0.5;