Parser: remove global state

The parser had global state in the form of a linear regression
and the "plot_depth" variable. Collect that in the deco_state struct and
pass it down the call-chain. Move out the code to update the
regression data to not bother other callers of tissue_tolerance_calc().

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Signed-off-by: Robert C. Helling <helling@atdotde.de>

3 files changed, 60 insertions, 54 deletions

diff --git a/core/deco.c b/core/deco.c
index cb8273f41..0dd4051c2 100644
--- a/core/deco.c
+++ b/core/deco.c
@@ -37,8 +37,6 @@
 // was introduced in v4.6.3 this can be set to a value of 1.0 which means no correction.
 #define subsurface_conservatism_factor 1.0
 
-extern int plot_depth;
-
 //! Option structure for Buehlmann decompression.
 struct buehlmann_config {
 	double satmult;			//! safety at inert gas accumulation as percentage of effect (more than 100).
@@ -157,10 +155,6 @@ static const double vpmb_conservatism_lvls[] = { 1.0, 1.05, 1.12, 1.22, 1.35 };
 
 #define TISSUE_ARRAY_SZ sizeof(ds->tissue_n2_sat)
 
-static int  sum1;
-static long sumx, sumxx;
-static double sumy, sumxy;
-
 static double get_crit_radius_He()
 {
 	if (vpmb_config.conservatism <= 4)
@@ -223,7 +217,6 @@ static double vpmb_tolerated_ambient_pressure(struct deco_state *ds, double refe
 	return ds->tissue_n2_sat[ci] + ds->tissue_he_sat[ci] + vpmb_config.other_gases_pressure - total_gradient;
 }
 
-
 double tissue_tolerance_calc(struct deco_state *ds, const struct dive *dive, double pressure)
 {
 	int ci = -1;
@@ -292,23 +285,6 @@ double tissue_tolerance_calc(struct deco_state *ds, const struct dive *dive, dou
 			}
 		// We are doing ok if the gradient was computed within ten centimeters of the ceiling.
 		} while (fabs(ret_tolerance_limit_ambient_pressure - reference_pressure) > 0.01);
-
-		if (plot_depth) {
-			++sum1;
-			sumx += plot_depth;
-			sumxx += (long)plot_depth * plot_depth;
-			double n2_gradient, he_gradient, total_gradient;
-			n2_gradient = update_gradient(ds, depth_to_bar(plot_depth, &displayed_dive), ds->bottom_n2_gradient[ds->ci_pointing_to_guiding_tissue]);
-			he_gradient = update_gradient(ds, depth_to_bar(plot_depth, &displayed_dive), ds->bottom_he_gradient[ds->ci_pointing_to_guiding_tissue]);
-			total_gradient = ((n2_gradient * ds->tissue_n2_sat[ds->ci_pointing_to_guiding_tissue]) + (he_gradient * ds->tissue_he_sat[ds->ci_pointing_to_guiding_tissue]))
-					/ (ds->tissue_n2_sat[ds->ci_pointing_to_guiding_tissue] + ds->tissue_he_sat[ds->ci_pointing_to_guiding_tissue]);
-
-			double buehlmann_gradient = (1.0 / ds->buehlmann_inertgas_b[ds->ci_pointing_to_guiding_tissue] - 1.0) * depth_to_bar(plot_depth, &displayed_dive) + ds->buehlmann_inertgas_a[ds->ci_pointing_to_guiding_tissue];
-			double gf = (total_gradient - vpmb_config.other_gases_pressure) / buehlmann_gradient;
-			sumxy += gf * plot_depth;
-			sumy += gf;
-			plot_depth = 0;
-		}
 	}
 	return ret_tolerance_limit_ambient_pressure;
 }
@@ -639,30 +615,50 @@ double get_gf(struct deco_state *ds, double ambpressure_bar, const struct dive *
 	return gf;
 }
 
-double regressiona()
+double regressiona(const struct deco_state *ds)
 {
-	if (sum1 > 1) {
-		double avxy = sumxy / sum1;
-		double avx = (double)sumx / sum1;
-		double avy = sumy / sum1;
-		double avxx = (double) sumxx / sum1;
+	if (ds->sum1 > 1) {
+		double avxy = ds->sumxy / ds->sum1;
+		double avx = (double)ds->sumx / ds->sum1;
+		double avy = ds->sumy / ds->sum1;
+		double avxx = (double) ds->sumxx / ds->sum1;
 		return (avxy - avx * avy) / (avxx - avx*avx);
 	}
 	else
 		return 0.0;
 }
 
-double regressionb()
+double regressionb(const struct deco_state *ds)
 {
-	if (sum1)
-		return sumy / sum1 - sumx * regressiona() / sum1;
+	if (ds->sum1)
+		return ds->sumy / ds->sum1 - ds->sumx * regressiona(ds) / ds->sum1;
 	else
 		return 0.0;
 }
 
-void reset_regression()
+void reset_regression(struct deco_state *ds)
 {
-	sum1 = 0;
-	sumxx = sumx = 0L;
-	sumy = sumxy = 0.0;
+	ds->sum1 = 0;
+	ds->sumxx = ds->sumx = 0L;
+	ds->sumy = ds->sumxy = 0.0;
+}
+
+void update_regression(struct deco_state *ds, const struct dive *dive)
+{
+	if (!ds->plot_depth)
+		return;
+	ds->sum1 += 1;
+	ds->sumx += ds->plot_depth;
+	ds->sumxx += (long)ds->plot_depth * ds->plot_depth;
+	double n2_gradient, he_gradient, total_gradient;
+	n2_gradient = update_gradient(ds, depth_to_bar(ds->plot_depth, dive), ds->bottom_n2_gradient[ds->ci_pointing_to_guiding_tissue]);
+	he_gradient = update_gradient(ds, depth_to_bar(ds->plot_depth, dive), ds->bottom_he_gradient[ds->ci_pointing_to_guiding_tissue]);
+	total_gradient = ((n2_gradient * ds->tissue_n2_sat[ds->ci_pointing_to_guiding_tissue]) + (he_gradient * ds->tissue_he_sat[ds->ci_pointing_to_guiding_tissue]))
+			/ (ds->tissue_n2_sat[ds->ci_pointing_to_guiding_tissue] + ds->tissue_he_sat[ds->ci_pointing_to_guiding_tissue]);
+
+	double buehlmann_gradient = (1.0 / ds->buehlmann_inertgas_b[ds->ci_pointing_to_guiding_tissue] - 1.0) * depth_to_bar(ds->plot_depth, dive) + ds->buehlmann_inertgas_a[ds->ci_pointing_to_guiding_tissue];
+	double gf = (total_gradient - vpmb_config.other_gases_pressure) / buehlmann_gradient;
+	ds->sumxy += gf * ds->plot_depth;
+	ds->sumy += gf;
+	ds->plot_depth = 0;
 }
diff --git a/core/deco.h b/core/deco.h
index 4bdc5840d..29a492c93 100644
--- a/core/deco.h
+++ b/core/deco.h
@@ -41,6 +41,10 @@ struct deco_state {
 	double gf_low_pressure_this_dive;
 	int deco_time;
 	bool icd_warning;
+	int  sum1;
+	long sumx, sumxx;
+	double sumy, sumxy;
+	int plot_depth;
 };
 
 extern const double buehlmann_N2_t_halflife[];
@@ -63,9 +67,10 @@ extern void vpmb_start_gradient(struct deco_state *ds);
 extern void clear_vpmb_state(struct deco_state *ds);
 extern void add_segment(struct deco_state *ds, double pressure, struct gasmix gasmix, int period_in_seconds, int setpoint, enum divemode_t divemode, int sac);
 
-extern double regressiona();
-extern double regressionb();
-extern void reset_regression();
+extern double regressiona(const struct deco_state *ds);
+extern double regressionb(const struct deco_state *ds);
+extern void reset_regression(struct deco_state *ds);
+extern void update_regression(struct deco_state *ds, const struct dive *dive);
 
 #ifdef __cplusplus
 }
diff --git a/core/planner.c b/core/planner.c
index 0743a6a52..e2c5cf035 100644
--- a/core/planner.c
+++ b/core/planner.c
@@ -36,7 +36,6 @@ static int decostoplevels_imperial[] = { 0, 3048, 6096, 9144, 12192, 15240, 1828
 					325120, 345440, 365760, 386080 };
 
 char *disclaimer;
-int plot_depth = 0;
 #if DEBUG_PLAN
 void dump_plan(struct diveplan *diveplan)
 {
@@ -557,23 +556,28 @@ static bool trial_ascent(struct deco_state *ds, int wait_time, int trial_depth,
 		add_segment(ds, depth_to_bar(trial_depth, dive),
 			    gasmix,
 			    wait_time, po2, divemode, prefs.decosac);
-	if (decoMode() == VPMB && (deco_allowed_depth(tissue_tolerance_calc(ds, dive,depth_to_bar(stoplevel, dive)),
-						      surface_pressure, dive, 1)
-				   > stoplevel)) {
-		restore_deco_state(trial_cache, ds, false);
-		free(trial_cache);
-		return false;
+	if (decoMode() == VPMB) {
+		double tolerance_limit = tissue_tolerance_calc(ds, dive, depth_to_bar(stoplevel, dive));
+		update_regression(ds, dive);
+		if (deco_allowed_depth(tolerance_limit, surface_pressure, dive, 1) > stoplevel) {
+			restore_deco_state(trial_cache, ds, false);
+			free(trial_cache);
+			return false;
+		}
 	}
 
 	while (trial_depth > stoplevel) {
+		double tolerance_limit;
 		int deltad = ascent_velocity(trial_depth, avg_depth, bottom_time) * TIMESTEP;
 		if (deltad > trial_depth) /* don't test against depth above surface */
 			deltad = trial_depth;
 		add_segment(ds, depth_to_bar(trial_depth, dive),
 			    gasmix,
 			    TIMESTEP, po2, divemode, prefs.decosac);
-		if (deco_allowed_depth(tissue_tolerance_calc(ds, dive, depth_to_bar(trial_depth, dive)),
-				       surface_pressure, dive, 1) > trial_depth - deltad) {
+		tolerance_limit = tissue_tolerance_calc(ds, dive, depth_to_bar(trial_depth, dive));
+		if (decoMode() == VPMB)
+			update_regression(ds, dive);
+		if (deco_allowed_depth(tolerance_limit, surface_pressure, dive, 1) > trial_depth - deltad) {
 			/* We should have stopped */
 			clear_to_ascend = false;
 			break;
@@ -878,7 +882,8 @@ bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, i
 		first_stop_depth = 0;
 		stopidx = bottom_stopidx;
 		ds->first_ceiling_pressure.mbar = depth_to_mbar(
-					deco_allowed_depth(tissue_tolerance_calc(ds, dive, depth_to_bar(depth, dive)), diveplan->surface_pressure / 1000.0, dive, 1),
+					deco_allowed_depth(tissue_tolerance_calc(ds, dive, depth_to_bar(depth, dive)),
+							   diveplan->surface_pressure / 1000.0, dive, 1),
 					dive);
 		if (ds->max_bottom_ceiling_pressure.mbar > ds->first_ceiling_pressure.mbar)
 			ds->first_ceiling_pressure.mbar = ds->max_bottom_ceiling_pressure.mbar;
@@ -894,7 +899,7 @@ bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, i
 			report_error(translate("gettextFromC", "Can't find gas %s"), gasname(gas));
 			current_cylinder = 0;
 		}
-		reset_regression();
+		reset_regression(ds);
 		while (1) {
 			/* We will break out when we hit the surface */
 			do {
@@ -918,7 +923,7 @@ bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, i
 				depth -= deltad;
 				/* Print VPM-Gradient as gradient factor, this has to be done from within deco.c */
 				if (decodive)
-					plot_depth = depth;
+					ds->plot_depth = depth;
 			} while (depth > 0 && depth > stoplevels[stopidx]);
 
 			if (depth <= 0)
@@ -1089,8 +1094,8 @@ bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, i
 
 	plan_add_segment(diveplan, clock - previous_point_time, 0, current_cylinder, po2, false, divemode);
 	if (decoMode() == VPMB) {
-		diveplan->eff_gfhigh = lrint(100.0 * regressionb());
-		diveplan->eff_gflow = lrint(100.0 * (regressiona() * first_stop_depth + regressionb()));
+		diveplan->eff_gfhigh = lrint(100.0 * regressionb(ds));
+		diveplan->eff_gflow = lrint(100.0 * (regressiona(ds) * first_stop_depth + regressionb(ds)));
 	}
 
 	for (int i = 0; i < MAX_CYLINDERS; i++)