+#define SAC_COLORS 9
+static const rgb_t sac_color[SAC_COLORS] = {
+ { 0.0, 0.4, 0.2},
+ { 0.2, 0.6, 0.2},
+ { 0.4, 0.8, 0.2},
+ { 0.6, 0.8, 0.2},
+ { 0.8, 0.8, 0.2},
+ { 0.8, 0.6, 0.2},
+ { 0.8, 0.4, 0.2},
+ { 0.9, 0.3, 0.2},
+ { 1.0, 0.2, 0.2},
+};
+
+/* set the color for the pressure plot according to temporary sac rate
+ * as compared to avg_sac; the calculation simply maps the delta between
+ * sac and avg_sac to indexes 0 .. (SAC_COLORS - 1) with everything
+ * more than 6000 ml/min below avg_sac mapped to 0 */
+
+static void set_sac_color(struct graphics_context *gc, int sac, int avg_sac)
+{
+ int sac_index = 0;
+ int delta = sac - avg_sac + 7000;
+
+ sac_index = delta / 2000;
+ if (sac_index < 0)
+ sac_index = 0;
+ if (sac_index > SAC_COLORS - 1)
+ sac_index = SAC_COLORS - 1;
+ set_source_rgb_struct(gc, &sac_color[sac_index]);
+}
+
+/* calculate the current SAC in ml/min and convert to int */
+#define GET_LOCAL_SAC(_entry1, _entry2, _dive) (int) \
+ ((GET_PRESSURE((_entry1)) - GET_PRESSURE((_entry2))) * \
+ (_dive)->cylinder[(_entry1)->cylinderindex].type.size.mliter / \
+ (((_entry2)->sec - (_entry1)->sec) / 60.0) / \
+ (1 + ((_entry1)->depth + (_entry2)->depth) / 20000.0) / \
+ 1000.0)
+
+#define SAC_WINDOW 45 /* sliding window in seconds for current SAC calculation */
+
+static void plot_cylinder_pressure(struct graphics_context *gc, struct plot_info *pi,
+ struct dive *dive)