diff options
Diffstat (limited to 'profile.c')
| -rw-r--r-- | profile.c | 34 |
1 files changed, 21 insertions, 13 deletions
@@ -1011,32 +1011,40 @@ static void set_sac_color(struct graphics_context *gc, int sac, int avg_sac) } } -static double get_local_sac(struct plot_data *entry1, struct plot_data *entry2, struct dive *dive) +/* Get local sac-rate (in ml/min) between entry1 and entry2 */ +static int get_local_sac(struct plot_data *entry1, struct plot_data *entry2, struct dive *dive) { int index = entry1->cylinderindex; - int delta_time = entry2->sec - entry1->sec; - double depth; - long delta_pressure = GET_PRESSURE(entry1) - GET_PRESSURE(entry2); - long mliter; + cylinder_t *cyl; + int duration = entry2->sec - entry1->sec; + int depth, airuse; + pressure_t a, b; + double atm; if (entry2->cylinderindex != index) return 0; - if (delta_pressure <= 0) + if (duration <= 0) return 0; - if (delta_time <= 0) + a.mbar = GET_PRESSURE(entry1); + b.mbar = GET_PRESSURE(entry2); + if (!a.mbar || !b.mbar) return 0; - depth = (entry1->depth + entry2->depth) / 2.0; - mliter = dive->cylinder[index].type.size.mliter; + /* Mean pressure in ATM */ + depth = (entry1->depth + entry2->depth) / 2; + atm = (double) depth_to_mbar(depth, dive) / SURFACE_PRESSURE; - return delta_pressure * mliter / - (delta_time / 60.0) / - depth_to_mbar(depth, dive); + cyl = dive->cylinder + index; + + airuse = gas_volume(cyl, a) - gas_volume(cyl, b); + + /* milliliters per minute */ + return airuse / atm * 60 / duration; } /* calculate the current SAC in ml/min and convert to int */ #define GET_LOCAL_SAC(_entry1, _entry2, _dive) \ - (int) get_local_sac(_entry1, _entry2, _dive) + get_local_sac(_entry1, _entry2, _dive) #define SAC_WINDOW 45 /* sliding window in seconds for current SAC calculation */ |