From 4c563359cf355375fee27d8c8931c47055e990bc Mon Sep 17 00:00:00 2001
From: ian <ian>
Date: Sun, 13 Feb 2005 16:49:02 +0000
Subject: [PATCH] lay_train seems done-ish

---
 hostside/safety.c | 54 +++++++++++++++++------------------------------
 hostside/safety.h | 12 ++++++-----
 2 files changed, 26 insertions(+), 40 deletions(-)

diff --git a/hostside/safety.c b/hostside/safety.c
index b33984c..099bad0 100644
--- a/hostside/safety.c
+++ b/hostside/safety.c
@@ -28,37 +28,39 @@ static voi seg_clear_stale(SegmentState *seg) {
 }
 
 static void lay_train(ErrorCode *ec, TrainNum tran,
-		      TrackLocation tloc, long distance,
-		      unsigned detect_now, unsigned detect_future,
-		      unsigned here_now, unsigned here_future,
-		      unsigned clash_if_updated) {
+		      TrackLocation tloc, long advance,
+		      unsigned detect, unsigned clash_if_updated) {
   SegmentState *seg;
+  long overall, remain;
 
   if (*ec) return;
 
+  remain= overall= advance + tra->speed * SPEED_CLEAR_MULT;
+
   for (;;) {
     seg= s->segs[tloc.segn];
     if (clash_if_updated && seg->tr_updated) {
       *ec= safety_problem(tloc.segn, tran, tran, "collision with itself");
       return;
     }
-    if (seg->here_future) {
+    if (seg->owned) {
       if (seg->owner != tran) {
 	*ec= safety_problem(tloc.segn, tran, seg->owner, "collision");
 	return;
       }
       seg_clear_stale(seg);
     }
-    seg->tran= tran;
+    seg->owned= 1;
+    seg->owner_backwards= tloc.backwards;
     seg->tr_updated= 1;
-    seg->tr_here_now |= here_now;
-    seg->tr_here_future |= here_future;
-    seg->tr_detect_now |= detect_now;
-    seg->tr_detect_future |= detect_future;
+    seg->tran= tran;
 
-    if (!distance) break;
-    
-    trackloc_further(&tloc, &distance);
+    dist_until= (overall - remain) - advance;
+    time_until= (SPEED_FACTOR * dist_until) / tra->speed;
+    *(detect ? &seg->until_detect : &seg->until_here)= time_until;
+
+    if (!remain) break;
+    trackloc_further(&tloc, &remain);
   }
 }
 
@@ -98,34 +100,16 @@ void safety_train_changed(TrainNum tran) {
     tloc.into= JUSTARRIVED_DIST;
 
   head= tra->backwards ? trai->tail : trai->head;
-  future= tra->speed * SPEED_CLEAR_MULT;
+  lay_train(tran, &ec, tloc, head, 0,1);
 
   ec= 0;
-  lay_train(tran, &ec, tloc, head + future, 0,0,0,1);
-  lay_train(tran, &ec, tloc, head,          0,0,1,1);
-  lay_train(tran, &ec, tloc,        future, 0,1,0,1);
-  lay_train(tran, &ec, tloc, 0,             1,1,1,1);
+  lay_train(&ec, tran, tloc, head, 0,1);
+  lay_train(&ec, tran, tloc, 0,    1,0);
   lay_train_done(tran);
-
   if (ec) return ec;
-  
-    
-	    (
-	    
-	    );
-  lay_train(tloc,
-	    tra->backwards ? trai->tail : trai->head,
-	    
-    
 
-  remain= 
-    mark segment as being owned by train but not detectable;
-    
 
-  for (
-       remain
-  while (remain) {
-    trackloc_further
+
 
 
   segi= &safety_segis[segn];
diff --git a/hostside/safety.h b/hostside/safety.h
index 454a4fe..06101d4 100644
--- a/hostside/safety.h
+++ b/hostside/safety.h
@@ -6,6 +6,7 @@
 typedef unsigned short TrainNum;
 typedef unsigned short SegmentNum;
 typedef unsigned short LocationNum;
+typedef short TimeInterval;
 typedef short Distance;
 typedef char Speed; /* non-negative, units of 4mm/s */
 
@@ -19,14 +20,15 @@ typedef struct {
 
 typedef struct {
   unsigned
-    tr_detect_now:1, tr_detect_future:1, /* owning train draws current */
-    tr_here_now:1, tr_here_future:1, /* owning train is or will use space */
-    tr_backwards:1, /* train's motion is (would be) backwards wrt track */
+    owned:1, /* this track segment is reserved for a train */
+    owner_backwards:1, /* train's motion is (would be) backwards wrt track */
     pt_sideways:1, /* points are set to `alternative'. (no points?: 0) */
-    tr_autostop:1, /* owning train is slow and wants to stop on detection */
+    autostop:1, /* owning train is slow and wants to stop on detection */
     tr_updated:1; /* for use by safety_train_changed etc.; otherwise 0 */
+  TimeInterval until_here, /* ) nonnegative; */  /* ) always valid but */
+    until_detect;          /* ) 0 if already */  /* )  only meaningful */
+  TrainNum owner;                                /* )  iff owned       */
   /*polarity?*/
-  TrainNum tran; /* always valid but only meaningful iff tr_here_future */
 } SegmentState;
 
 typedef struct {
-- 
2.30.2