Ascend along fixed stops instead of along rounded ceiling

4 files changed, 47 insertions, 114 deletions

diff --git a/src/deco.c b/src/deco.c
index 3f27a33..51cdf0e 100644
--- a/src/deco.c
+++ b/src/deco.c
@@ -197,31 +197,17 @@ double get_gf(const decostate_t *ds, const double depth)
     const unsigned char lo = ds->gflo;
     const unsigned char hi = ds->gfhi;
 
-    const double last_stop_gauge = LAST_STOP_AT_SIX ? msw_to_bar(6) : ds->ceil_multiple;
-
     if (ds->firststop == -1)
         return lo;
 
-    if (depth <= SURFACE_PRESSURE + last_stop_gauge)
+    if (depth <= SURFACE_PRESSURE)
         return hi;
 
     if (depth >= ds->firststop)
         return lo;
 
     /* interpolate lo and hi between first stop and last stop */
-    return hi - (hi - lo) * gauge_depth(depth - ds->ceil_multiple) / gauge_depth(ds->firststop - ds->ceil_multiple);
-}
-
-double round_ceiling(const decostate_t *ds, const double c)
-{
-    assert(ds->ceil_multiple != 0);
-
-    double ceil_gauge = ds->ceil_multiple * ceil(RND(gauge_depth(c) / ds->ceil_multiple));
-
-    if (LAST_STOP_AT_SIX && ceil_gauge < msw_to_bar(6) && ceil_gauge > 0)
-        return abs_depth(msw_to_bar(6));
-    else
-        return abs_depth(ceil_gauge);
+    return hi - (hi - lo) * gauge_depth(depth) / gauge_depth(ds->firststop);
 }
 
 double ceiling(const decostate_t *ds, double gf)
@@ -249,7 +235,7 @@ double ceiling(const decostate_t *ds, double gf)
         c = max(c, ((pn2 + phe) - (a * gf)) / (gf / b + 1 - gf));
     }
 
-    return round_ceiling(ds, c);
+    return c;
 }
 
 double gf99(const decostate_t *ds, double depth)
diff --git a/src/deco.h b/src/deco.h
index 11f6bc9..cef35d4 100644
--- a/src/deco.h
+++ b/src/deco.h
@@ -75,7 +75,6 @@ double add_segment_ascdec(decostate_t *ds, const double dstart, const double den
                           const gas_t *gas);
 double add_segment_const(decostate_t *ds, const double depth, const double time, const gas_t *gas);
 double get_gf(const decostate_t *ds, const double depth);
-double round_ceiling(const decostate_t *ds, const double c);
 double ceiling(const decostate_t *ds, double gf);
 double gf99(const decostate_t *ds, double depth);
 
diff --git a/src/schedule.c b/src/schedule.c
index bf5a8ec..00a2b13 100644
--- a/src/schedule.c
+++ b/src/schedule.c
@@ -18,7 +18,7 @@ const gas_t *best_gas(const double depth, const gas_t *gasses, const int nof_gas
     for (int i = 0; i < nof_gasses; i++) {
         double mod = gas_mod(&gasses[i]);
 
-        if (depth <= mod && (mod_best == -1 || mod < mod_best)) {
+        if (depth - mod < 1E-2 && (mod_best == -1 || mod < mod_best)) {
             best = &gasses[i];
             mod_best = mod;
         }
@@ -27,23 +27,6 @@ const gas_t *best_gas(const double depth, const gas_t *gasses, const int nof_gas
     return best;
 }
 
-const gas_t *next_gas(const double depth, const gas_t *gasses, const int nof_gasses)
-{
-    const gas_t *next = NULL;
-    double mod_best = 0;
-
-    for (int i = 0; i < nof_gasses; i++) {
-        double mod = gas_mod(&gasses[i]);
-
-        if (depth > mod && mod > mod_best) {
-            next = &gasses[i];
-            mod_best = mod;
-        }
-    }
-
-    return next;
-}
-
 int direct_ascent(const decostate_t *ds, const double depth, const double time, const gas_t *gas)
 {
     decostate_t ds_ = *ds;
@@ -109,7 +92,8 @@ double calc_ndl(decostate_t *ds, const double depth, const double ascrate, const
     return ndl;
 }
 
-double deco_stop(decostate_t *ds, const double depth, const double current_gf, const gas_t *gas)
+double deco_stop(decostate_t *ds, const double depth, const double next_stop, const double current_gf,
+                 const gas_t *gas)
 {
     double stoplen = 0;
 
@@ -119,7 +103,7 @@ double deco_stop(decostate_t *ds, const double depth, const double current_gf, c
     for (;;) {
         double tmp = add_segment_const(&ds_, depth, STOPLEN_ROUGH, gas);
 
-        if (ceiling(&ds_, current_gf) != depth)
+        if (ceiling(&ds_, current_gf) <= next_stop)
             break;
 
         stoplen += tmp;
@@ -129,33 +113,15 @@ double deco_stop(decostate_t *ds, const double depth, const double current_gf, c
         add_segment_const(ds, depth, stoplen, gas);
 
     /* fine steps */
-    while (ceiling(ds, current_gf) == depth)
+    while (ceiling(ds, current_gf) > next_stop)
         stoplen += add_segment_const(ds, depth, STOPLEN_FINE, gas);
 
     return stoplen;
 }
 
-int should_switch(const gas_t **next, double *switch_depth, const decostate_t *ds, const double depth,
-                  const double next_stop, const gas_t *deco_gasses, const int nof_gasses)
+static int surfaced(const double depth)
 {
-    /* check if we switch at MOD or just at stops */
-    if (!SWITCH_INTERMEDIATE)
-        return 0;
-
-    /* check if there is a gas to switch to */
-    *next = next_gas(depth, deco_gasses, nof_gasses);
-
-    if (*next == NULL)
-        return 0;
-
-    /* check if the switch happens before the current ceiling */
-    *switch_depth = round_ceiling(ds, (*next)->mod) - ds->ceil_multiple;
-    assert(*switch_depth <= (*next)->mod);
-
-    if (*switch_depth <= next_stop)
-        return 0;
-
-    return 1;
+    return fabs(depth - SURFACE_PRESSURE) < 1E-2;
 }
 
 decoinfo_t calc_deco(decostate_t *ds, const double start_depth, const gas_t *start_gas, const gas_t *deco_gasses,
@@ -175,44 +141,20 @@ decoinfo_t calc_deco(decostate_t *ds, const double start_depth, const gas_t *sta
         return ret;
     }
 
-    /* determine first stop */
-    double current_gf = get_gf(ds, depth);
+    double next_stop = abs_depth(ds->ceil_multiple * (ceil(gauge_depth(depth) / ds->ceil_multiple) - 1));
+    double current_gf = get_gf(ds, next_stop);
 
-    if (ds->firststop == -1)
-        ds->firststop = ceiling(ds, current_gf);
-
-    /* switch to best deco gas if there is one available */
-    const gas_t *best = best_gas(depth, deco_gasses, nof_gasses);
-
-    if (best)
-        gas = best;
-
-    /* alternate between ascending and stopping */
     for (;;) {
         /* extra bookkeeping because waypoints and segments do not match 1:1 */
         double last_waypoint_depth = depth;
         double waypoint_time;
 
-        /* ascend */
-        for (;;) {
-            /* determine next stop */
-            double next_stop = ceiling(ds, current_gf);
-
-            /* find out if we need to switch gas on the way */
-            const gas_t *next;
-            double switch_depth;
-
-            if (should_switch(&next, &switch_depth, ds, depth, next_stop, deco_gasses, nof_gasses)) {
-                /* ascend to gas switch */
-                ret.tts += add_segment_ascdec(ds, depth, switch_depth, fabs(depth - switch_depth) / asc_per_min, gas);
-                depth = switch_depth;
-                current_gf = get_gf(ds, depth);
-
-                /*
-                 * since we're stopping for a switch next, this is the last of
-                 * any number of consecutive travel segments and the waypoint
-                 * callback should be called.
-                 */
+        while (ceiling(ds, current_gf) < next_stop && !surfaced(depth)) {
+            /* switch to better gas if available */
+            const gas_t *best = best_gas(depth, deco_gasses, nof_gasses);
+
+            if (SWITCH_INTERMEDIATE && best && best != gas) {
+                /* emit waypoint */
                 waypoint_time = fabs(last_waypoint_depth - depth) / asc_per_min;
 
                 if (wp_cb)
@@ -221,9 +163,9 @@ decoinfo_t calc_deco(decostate_t *ds, const double start_depth, const gas_t *sta
                 last_waypoint_depth = depth;
 
                 /* switch gas */
-                gas = next;
+                gas = best;
 
-                ret.tts += add_segment_const(ds, switch_depth, 1, gas);
+                ret.tts += add_segment_const(ds, depth, 1, gas);
 
                 if (wp_cb)
                     wp_cb(ds, (waypoint_t){.depth = depth, .time = 1, .gas = gas}, SEG_GAS_SWITCH);
@@ -231,32 +173,40 @@ decoinfo_t calc_deco(decostate_t *ds, const double start_depth, const gas_t *sta
                 continue;
             }
 
-            /* ascend to current ceiling */
+            /* ascend to next stop */
             ret.tts += add_segment_ascdec(ds, depth, next_stop, fabs(depth - next_stop) / asc_per_min, gas);
             depth = next_stop;
-            current_gf = get_gf(ds, depth);
 
-            /* if the ceiling moved while we ascended, keep ascending */
-            if (depth > ceiling(ds, current_gf))
-                continue;
+            /* make next stop shallower */
+            next_stop -= ds->ceil_multiple;
+
+            if (LAST_STOP_AT_SIX && next_stop < abs_depth(msw_to_bar(6)))
+                next_stop = SURFACE_PRESSURE;
+
+            /* recalculate gf */
+            current_gf = get_gf(ds, next_stop);
+        }
+
+        if (ds->firststop == -1) {
+            ds->firststop = depth;
 
             /*
-             * since we've actually reached the ceiling, this is the last of
-             * any number of consecutive travel segments and the waypoint
-             * callback should be called.
+             * if the first stop wasn't know yet during the previous call to
+             * get_gf, the result was inaccurate and needs to be recalculated
              */
-            waypoint_time = fabs(last_waypoint_depth - depth) / asc_per_min;
-            enum segtype_t segtype = depth <= abs_depth(0) ? SEG_SURFACE : SEG_TRAVEL;
+            current_gf = get_gf(ds, next_stop);
+        }
 
-            if (wp_cb)
-                wp_cb(ds, (waypoint_t){.depth = depth, .time = waypoint_time, .gas = gas}, segtype);
+        /* emit waypoint */
+        waypoint_time = fabs(last_waypoint_depth - depth) / asc_per_min;
+        enum segtype_t segtype = surfaced(depth) ? SEG_SURFACE : SEG_TRAVEL;
 
-            break;
-        }
+        if (wp_cb && waypoint_time)
+            wp_cb(ds, (waypoint_t){.depth = depth, .time = waypoint_time, .gas = gas}, segtype);
 
         /* terminate if we surfaced */
-        if (depth <= abs_depth(0))
-            break;
+        if (surfaced(depth))
+            return ret;
 
         /* switch to better gas if available */
         const gas_t *best = best_gas(depth, deco_gasses, nof_gasses);
@@ -264,13 +214,12 @@ decoinfo_t calc_deco(decostate_t *ds, const double start_depth, const gas_t *sta
         if (best)
             gas = best;
 
-        /* stop */
-        double stoplen = deco_stop(ds, depth, current_gf, gas);
+        /* stop until ceiling rises above next stop */
+        double stoplen = deco_stop(ds, depth, next_stop, current_gf, gas);
+
         ret.tts += stoplen;
 
         if (wp_cb)
             wp_cb(ds, (waypoint_t){.depth = depth, .time = stoplen, .gas = gas}, SEG_DECO_STOP);
     }
-
-    return ret;
 }
diff --git a/src/schedule.h b/src/schedule.h
index 2af6481..e3b69ec 100644
--- a/src/schedule.h
+++ b/src/schedule.h
@@ -36,7 +36,6 @@ extern int SWITCH_INTERMEDIATE;
 typedef void (*waypoint_callback_t)(const decostate_t *ds, const waypoint_t, const segtype_t);
 
 const gas_t *best_gas(const double depth, const gas_t *gasses, const int nof_gasses);
-const gas_t *next_gas(const double depth, const gas_t *gasses, const int nof_gasses);
 
 int direct_ascent(const decostate_t *ds, const double depth, const double time, const gas_t *gas);
 double calc_ndl(decostate_t *ds, const double depth, const double ascrate, const gas_t *gas);