From: ian <ian>
Date: Sun, 4 May 2008 22:11:43 +0000 (+0000)
Subject: no really proper tail-eating
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=d0fc7aabe33c7587b84f9d93d618b0c4609117e6;p=trains.git

no really proper tail-eating
---

diff --git a/hostside/resolve.c b/hostside/resolve.c
index 4b0350d..63ba1f6 100644
--- a/hostside/resolve.c
+++ b/hostside/resolve.c
@@ -506,7 +506,7 @@ static int resolve_complete_ends_train(Train *tra) {
   }
 
   report_train_position(tra);
-  report_train_ownerships(tra, u.furthest, 0);
+  report_train_ownerships(tra, t.seg, 1);
 
   return 0;
 }
diff --git a/hostside/safety.c b/hostside/safety.c
index 859465d..c4ef91c 100644
--- a/hostside/safety.c
+++ b/hostside/safety.c
@@ -235,7 +235,7 @@ typedef struct {
     count_time:1,
     accelerating:1,
     usecurrentposn:1, /* for pred_getmovpos */
-    forceusemotions:1, /* for report_train_ownerships only */
+    alwaysusemotions:1, /* for report_train_ownerships only */
     walk_compute_polarise:1, /* nose_nextseg still needs to worry */
     need_polarise:1, /* when we commit */
     train_polarity_inverted:1, /* right now, or if know_best, the best */
@@ -244,7 +244,7 @@ typedef struct {
   TrackAdvanceContext nosec, tailc, fdetc;
   TimeInterval elapsed; /* from now, minimum */
   Distance was_distance;
-  Segment *furthest;
+  Segment *hindmost;
 
   PredictionProblemCallback *problem_callback;
   void *problem_callback_u;
@@ -292,7 +292,7 @@ static void pred_callback_debug(const char *what, TrackLocation *t,
   PredictUserContext *u= c->u;
   
   oprintf(DUPO("safety") " predict   %s"
-	  " %s%s until=%ld dist=%d (was %d) %c%c%c.%c  %c%c%c%c.%c%c%c%c"
+	  " %s%s until=%ld dist=%d (was %d) %c%c%c.%c  %c%c%c.%c%c%c%c"
 	  " elapsed=%ld nit=%d,%d\n",
 	  what,
 	  t->backwards?"-":"", t->seg->i->pname, (long)t->seg->until,
@@ -307,7 +307,6 @@ static void pred_callback_debug(const char *what, TrackLocation *t,
 	  "-t"[ u->count_time ],
 	  "-a"[ u->accelerating ],
 	  "-c"[ u->usecurrentposn ],
-	  "-f"[ u->forceusemotions ],
 	  
 	  "-w"[ u->walk_compute_polarise ],
 	  "-n"[ u->need_polarise ],
@@ -444,7 +443,6 @@ static int nose_nextseg(TrackLocation *t, TrackAdvanceContext *c,
   t->seg->tr_backwards= t->backwards;
   t->seg->pred_present= 1;
   t->seg->until= u->elapsed;
-  u->furthest= t->seg;
   return 0; /* yay! */
 }
 
@@ -592,9 +590,8 @@ static int report_nextseg(TrackLocation *t, struct TrackAdvanceContext *c,
   int r;
 
   if (t->seg->owner != u->train) return -1;
-  if (t->seg == u->furthest) {
-    /* We've gone back past our own tail into the place where our
-     * head is going to be in the far future.   */
+  if (t->seg == u->hindmost && t->seg->tr_backwards == t->backwards) {
+    /* We've looped the loop. */
     oprintf(UPO, " ...");
     return -1;
   }
@@ -607,10 +604,10 @@ static int report_nextseg(TrackLocation *t, struct TrackAdvanceContext *c,
     strcat(flags,".");
   if (t->seg == u->train->foredetect) {
     strcat(flags,"!");
-    u->usecurrentposn=u->forceusemotions;
+    u->usecurrentposn= 0;
   }
 
-  oprintf(UPO," %s%s", t->seg->tr_backwards?"-":"", t->seg->i->pname);
+  oprintf(UPO," %s%s", t->backwards?"-":"", t->seg->i->pname);
 
   if (t->seg->i->n_poscombs > 1) {
     r= pred_getmovpos(t,c,mpc);  assert(!r);  assert(*mpc>=0);
@@ -621,35 +618,35 @@ static int report_nextseg(TrackLocation *t, struct TrackAdvanceContext *c,
   return 0;
 }
 
-void report_train_ownerships(Train *tra, Segment *furthest,
-			     int force_use_motions) {
+void report_train_ownerships(Train *tra, Segment *hindmost,
+			     int always_use_motions) {
   PredictUserContext u;
   MovPosComb mpc;
   int r;
 
   memset(&u,0,sizeof(u));
   u.train= tra;
-  u.furthest= 0;
-  u.usecurrentposn= 0;
-  u.forceusemotions= force_use_motions;
+  u.hindmost= 0;
+  u.alwaysusemotions= always_use_motions;
+  u.usecurrentposn= !always_use_motions;
   
-  /* Walk backwards along the train printing its segments: */
+  /* Walk along the train printing its segments: */
   oprintf(UPO, "train %s has", tra->pname);
   
-  u.tail.seg= furthest;
-  u.tail.remain= 0;
-  u.tail.backwards= !u.tail.seg->tr_backwards;
+  u.nose.seg= hindmost;
+  u.nose.remain= 0;
+  u.nose.backwards= hindmost->tr_backwards;
 
-  u.tailc.distance= TL_DIST_INF;;
-  u.tailc.nextseg= report_nextseg;
-  u.tailc.getmovpos= pred_getmovpos;
-  u.tailc.u= &u;
+  u.nosec.distance= TL_DIST_INF;;
+  u.nosec.nextseg= report_nextseg;
+  u.nosec.getmovpos= pred_getmovpos;
+  u.nosec.u= &u;
 
-  mpc= furthest->movposcomb;
-  r= report_nextseg(&u.tail,&u.tailc,&mpc,0);  assert(!r);
+  mpc= u.nose.seg->movposcomb;
+  r= report_nextseg(&u.nose,&u.nosec,&mpc,0);  assert(!r);
 
-  u.furthest= furthest;
-  trackloc_advance(&u.tail,&u.tailc);
+  u.hindmost= hindmost;
+  trackloc_advance(&u.nose,&u.nosec);
 
   oprintf(UPO, "\n");
 }
@@ -690,7 +687,6 @@ ErrorCode predict(Train *tra, int accelerate,
   u.accelerating= accelerate;
   u.walk_compute_polarise= 1;
   u.train_polarity_inverted= foredet->seg_inverted ^ foredet->tr_backwards;
-  u.furthest= tra->foredetect;
   u.usecurrentposn= 1;
 
   u.fdetc.getmovpos= pred_getmovpos;
@@ -717,6 +713,8 @@ ErrorCode predict(Train *tra, int accelerate,
   ec= trackloc_advance(&u.tail,&u.tailc);  assert(!ec);
   trackloc_reverse_exact(&u.tail,0);
 
+  u.hindmost= u.tail.seg;
+
   /* find the train's nose */
 
   u.nose= u.fdet;
@@ -790,7 +788,7 @@ ErrorCode predict(Train *tra, int accelerate,
   if (u.need_polarise)
     actual_inversions_done();
 
-  report_train_ownerships(tra,u.furthest,0);
+  report_train_ownerships(tra,u.hindmost,0);
   return 0;
 
  xproblem:
diff --git a/hostside/safety.h b/hostside/safety.h
index 458494d..520867b 100644
--- a/hostside/safety.h
+++ b/hostside/safety.h
@@ -117,7 +117,7 @@ ErrorCode predict(Train *tra, int accelerate,
 
 void report_train_position(Train *tra);
 void report_train_ownerships(Train *tra, Segment *furthest,
-			     int force_use_motions);
+			     int always_use_motions);
   /* ... for use by things which update these only, which
    * is basically safety.c and resolve.c */