From: ian <ian>
Date: Sun, 13 Apr 2008 22:15:28 +0000 (+0000)
Subject: check points wrong way
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=daaaf9a59811785491d058950cb0b5a932b91c09;p=trains.git

check points wrong way
---

diff --git a/hostside/TODO b/hostside/TODO
index f3aaccf..4646e4f 100644
--- a/hostside/TODO
+++ b/hostside/TODO
@@ -2,7 +2,6 @@ dunno but maybe before can test
 	wiring to gui display
 
 things not yet considered at all in safety code
-	coming up against points the wrong way
 	min. curve specifications
 
 
diff --git a/hostside/safety.c b/hostside/safety.c
index 381f9fc..cca1f99 100644
--- a/hostside/safety.c
+++ b/hostside/safety.c
@@ -72,8 +72,6 @@ static void lay_train_check_clash(LayTrainState *l, Segment *check,
       return;
     }
   }
-  if (check->movposcomb < 0)
-    l->ec= safety_problem(l->tra, report, "track route not set");
 }
 
 static void lay_train_pass(LayTrainState *l,
@@ -129,7 +127,25 @@ static void lay_train_pass(LayTrainState *l,
     *(check_clash ? &seg->until_here : &seg->until_detect)= time_until;
 
     if (!remain) break;
-    trackloc_further(&tloc, &remain);
+    int r= trackloc_further(&tloc, &remain);
+
+    if (r==-2) {
+      l->ec= safety_problem(l->tra, seg, "end of track");
+      return;
+    }
+    if (r==-1) {
+      l->ec= safety_problem(l->tra, seg, "track route not set");
+      return;
+    }
+    if (r>1) {
+      const SegPosCombInfo *pci= trackloc_segposcomb(&tloc);
+      const SegmentLinkInfo *link= trackloc_segmentlink(&tloc,pci,0);
+      if (link->next+segments != seg) {
+	l->ec= safety_problem(l->tra, link->next+segments,
+			      "track route set against us");
+	return;
+      }
+    }
   }
 }
 
diff --git a/hostside/safety.h b/hostside/safety.h
index 8796661..4d895a4 100644
--- a/hostside/safety.h
+++ b/hostside/safety.h
@@ -241,9 +241,16 @@ struct TrackLocation { /* transparent, and manipulable by trackloc_... fns */
 long trackloc_remaininseg(const TrackLocation *tloc);
   /* Returns dist that tloc can advance before it goes into next segment. */
 
-void trackloc_further(TrackLocation *tloc, long *remain_io);
-  /* Advances tloc, decrementing *remain_io, until either
-   * *remain_io becomes zero, or tloc->segn changes. */
+int trackloc_further(TrackLocation *tloc, long *remain_io);
+  /* Advances tloc, decrementing *remain_io, until one of the
+   * following happens:
+   *    tloc->segn changes               returns +1
+   *    *remain_io becomes zero          returns  0
+   *    unknown movpos found             returns -1
+   *    end of track reached             returns -2
+   * Does _not_ check that the movposcomb of the segment we
+   * are moving into is correct.
+   */
 
 void trackloc_reverse(TrackLocation *tloc);
   /* Reverses tloc without changing its actual location. */
diff --git a/hostside/trackloc.c b/hostside/trackloc.c
index 0818c6b..4d0ba11 100644
--- a/hostside/trackloc.c
+++ b/hostside/trackloc.c
@@ -8,6 +8,7 @@
 const SegPosCombInfo *trackloc_segposcomb(const TrackLocation *tloc) {
   Segment *seg= tloc->seg;
 
+  if (seg->movposcomb<0) return 0;
   assert(seg->movposcomb < seg->i->n_poscombs);
   return &seg->i->poscombs[seg->movposcomb];
 }
@@ -17,7 +18,7 @@ const SegmentLinkInfo *trackloc_segmentlink(const TrackLocation *tloc,
 					    unsigned far) {
   return (tloc->backwards ^ far) ? &pci->backwards : &pci->forwards;
 }
-  
+
 long trackloc_remaininseg(const TrackLocation *tloc) {
   const SegPosCombInfo *pci;
   long segment_len;
@@ -28,7 +29,7 @@ long trackloc_remaininseg(const TrackLocation *tloc) {
   return segment_len - tloc->into;
 }  
 
-void trackloc_further(TrackLocation *tloc, long *remain_io) {
+int trackloc_further(TrackLocation *tloc, long *remain_io) {
   const SegPosCombInfo *pci;
   const SegmentLinkInfo *lnki_far;
   long segment_remain;
@@ -38,13 +39,18 @@ void trackloc_further(TrackLocation *tloc, long *remain_io) {
   if (*remain_io <= segment_remain) {
     tloc->into += *remain_io;
     *remain_io= 0;
+    return 0;
   } else {
+    *remain_io -= segment_remain;
+    tloc->into += segment_remain;
     pci= trackloc_segposcomb(tloc);
+    if (!pci) return -1;
     lnki_far= trackloc_segmentlink(tloc, pci, 1);
-    *remain_io -= segment_remain;
+    if (!SOMEP(lnki_far->next)) return -2;
     tloc->seg= &segments[lnki_far->next];
     tloc->into= 0;
     tloc->backwards ^= lnki_far->next_backwards;
+    return +1;
   }
 }