Add the ability to cache our deco state

We kept reduing all the deco calculations, including the previous dives
(if any) for each segment we add to the dive plan. This simply remembers
the last stage and then just adds to that.

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

1 files changed, 44 insertions, 0 deletions

diff --git a/deco.c b/deco.c
index 05adba555..cd8f417d1 100644
--- a/deco.c
+++ b/deco.c
@@ -11,8 +11,11 @@
  * deco_allowed_depth(tissues_tolerance, surface_pressure, dive, smooth)
  *				- ceiling based on lead tissue, surface pressure, 3m increments or smooth
  * set_gf(gflow, gfhigh) - set Buehlmann gradient factors
+ * void cache_deco_state(tissue_tolerance, char **datap) - cache the relevant data allocate memory if needed
+ * double restore_deco_state(char *data) - restore the state and return the tissue_tolerance
  */
 #include <math.h>
+#include <string.h>
 #include "dive.h"
 
 //! Option structure for Buehlmann decompression.
@@ -88,6 +91,7 @@ double tissue_he_sat[16];
 double tissue_tolerated_ambient_pressure[16];
 int ci_pointing_to_guiding_tissue;
 double gf_low_position_this_dive;
+#define TISSUE_ARRAY_SZ sizeof(tissue_n2_sat)
 
 static double actual_gradient_limit(const struct dive_data *data)
 {
@@ -222,6 +226,46 @@ void clear_deco(double surface_pressure)
 	gf_low_position_this_dive = buehlmann_config.gf_low_position_min;
 }
 
+void cache_deco_state(double tissue_tolerance, char **cached_datap)
+{
+	char *data = *cached_datap;
+
+	if (!data) {
+		data = malloc(3 * TISSUE_ARRAY_SZ + 2 * sizeof(double) + sizeof(int));
+		*cached_datap = data;
+	}
+	memcpy(data, tissue_n2_sat, TISSUE_ARRAY_SZ);
+	data += TISSUE_ARRAY_SZ;
+	memcpy(data, tissue_he_sat, TISSUE_ARRAY_SZ);
+	data += TISSUE_ARRAY_SZ;
+	memcpy(data, tissue_tolerated_ambient_pressure, TISSUE_ARRAY_SZ);
+	data += TISSUE_ARRAY_SZ;
+	memcpy(data, &gf_low_position_this_dive, sizeof(double));
+	data += sizeof(double);
+	memcpy(data, &tissue_tolerance, sizeof(double));
+	data += sizeof(double);
+	memcpy(data, &ci_pointing_to_guiding_tissue, sizeof(int));
+}
+
+double restore_deco_state(char *data)
+{
+	double tissue_tolerance;
+
+	memcpy(tissue_n2_sat, data, TISSUE_ARRAY_SZ);
+	data += TISSUE_ARRAY_SZ;
+	memcpy(tissue_he_sat, data, TISSUE_ARRAY_SZ);
+	data += TISSUE_ARRAY_SZ;
+	memcpy(tissue_tolerated_ambient_pressure, data, TISSUE_ARRAY_SZ);
+	data += TISSUE_ARRAY_SZ;
+	memcpy(&gf_low_position_this_dive, data, sizeof(double));
+	data += sizeof(double);
+	memcpy(&tissue_tolerance, data, sizeof(double));
+	data += sizeof(double);
+	memcpy(&ci_pointing_to_guiding_tissue, data, sizeof(int));
+
+	return tissue_tolerance;
+}
+
 unsigned int deco_allowed_depth(double tissues_tolerance, double surface_pressure, struct dive *dive, gboolean smooth)
 {
 	unsigned int depth, multiples_of_3m;