subs: Make shp_check_nav() more like lnd_check_mar()

No functional change.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

include/sect.h

@@ -30,7 +30,7 @@
  *     Dave Pare
  *     Ken Stevens, 1995
  *     Steve McClure, 1998
- *     Markus Armbruster, 2004-2010
+ *     Markus Armbruster, 2004-2014
  */
 
 
@@ -92,6 +92,14 @@ struct sctstr {
     unsigned char sct_defense;	/* Defensive value of a sector */
 };
 
+enum d_navigation {
+    NAV_NONE,	/* ships can't navigate */
+    NAVOK,	/* ships can always navigate */
+    NAV_02,	/* requires 2% effic to navigate */
+    NAV_CANAL,	/* requires 2% effic to navigate and M_CANAL capability */
+    NAV_60	/* requires 60% effic to navigate */
+};
+
 struct dchrstr {
     unsigned char d_uid;
     char d_mnem;		/* map symbol */

include/ship.h

@@ -139,6 +139,14 @@ enum {
     SHP_TORP_SHELLS = 3		/* number of shells used by a torpedo */
 };
 
+/* Whether and why a ship is stuck in a sector */
+enum shp_stuck {
+    SHP_STUCK_NOT,		/* not stuck */
+    SHP_STUCK_CONSTRUCTION,	/* sector not efficient enough */
+    SHP_STUCK_CANAL,		/* ship lacks M_CANAL */
+    SHP_STUCK_IMPASSABLE	/* sector type not navigable */
+};
+
 extern int m_armor(struct mchrstr *, int);
 extern int m_speed(struct mchrstr *, int);
 extern int m_visib(struct mchrstr *, int);
@@ -165,7 +173,7 @@ extern void shp_sel(struct nstr_item *, struct emp_qelem *);
 extern struct ulist *shp_insque(struct shpstr *, struct emp_qelem *);
 extern void shp_nav(struct emp_qelem *, double *, double *, int *, natid);
 extern int shp_sweep(struct emp_qelem *, int, int, natid);
-extern enum d_navigation shp_check_nav(struct shpstr *, struct sctstr *);
+extern enum shp_stuck shp_check_nav(struct shpstr *, struct sctstr *);
 extern int sect_has_dock(struct sctstr *);
 extern int shp_hardtarget(struct shpstr *);
 extern int shp_nav_one_sector(struct emp_qelem *, int, natid, int);

include/types.h

@@ -27,7 +27,7 @@
  *  types.h: Empire types
  *
  *  Known contributors to this file:
- *     Markus Armbruster, 2006-2013
+ *     Markus Armbruster, 2006-2014
  */
 
 #ifndef TYPES_H
@@ -36,14 +36,6 @@
 typedef unsigned char natid;	/* NSC_NATID must match this */
 typedef short coord;
 
-enum d_navigation {
-    NAV_NONE,	/* ships can't navigate */
-    NAVOK,	/* ships can always navigate */
-    NAV_02,	/* requires 2% effic to navigate */
-    NAV_CANAL,	/* requires 2% effic to navigate and M_CANAL capability */
-    NAV_60	/* requires 60% effic to navigate */
-};
-
 struct bp;
 struct emp_qelem;
 struct empobj;

src/lib/subs/retreat.c

@@ -146,24 +146,20 @@ retreat_ship1(struct shpstr *sp, char code, int orig)
 
     getsect(sp->shp_x, sp->shp_y, &sect);
     switch (shp_check_nav(sp, &sect)) {
-    case NAV_02:
+    case SHP_STUCK_NOT:
-    case NAV_60:
+	break;
+    case SHP_STUCK_CONSTRUCTION:
 	wu(0, sp->shp_own,
 	   "%s %s,\nbut was caught in a construction zone, and couldn't retreat!\n",
 	   prship(sp), conditions[findcondition(code)].desc[orig]);
 	return 0;
-    case NAV_NONE:
-    case NAV_CANAL:
-	wu(0, sp->shp_own,
-	   "%s %s,\nbut was landlocked, and couldn't retreat!\n",
-	   prship(sp), conditions[findcondition(code)].desc[orig]);
-	return 0;
-    case NAVOK:
-	break;
     default:
 	CANT_REACH();
+	/* fall through */
+    case SHP_STUCK_CANAL:
+    case SHP_STUCK_IMPASSABLE:
 	wu(0, sp->shp_own,
-	   "%s %s,\nbut was subject to an empire error, and couldn't retreat!\n",
+	   "%s %s,\nbut was landlocked, and couldn't retreat!\n",
 	   prship(sp), conditions[findcondition(code)].desc[orig]);
 	return 0;
     }
@@ -199,7 +195,7 @@ retreat_ship1(struct shpstr *sp, char code, int orig)
 	mobcost = shp_mobcost(sp);
 
 	getsect(newx, newy, &sect);
-	if (shp_check_nav(sp, &sect) != NAVOK ||
+	if (shp_check_nav(sp, &sect) != SHP_STUCK_NOT ||
 	    (sect.sct_own
 	     && relations_with(sect.sct_own, sp->shp_own) < FRIENDLY)) {
 	    wu(0, sp->shp_own, "%s %s,\nbut could not retreat to %s!\n",

src/lib/subs/shpsub.c

@@ -142,19 +142,17 @@ shp_nav(struct emp_qelem *list, double *minmobp, double *maxmobp,
 	    continue;
 	}
 	switch (shp_check_nav(sp, &sect)) {
-	case NAV_02:
+	case SHP_STUCK_NOT:
-	case NAV_60:
+	    break;
+	case SHP_STUCK_CONSTRUCTION:
 	    shp_stays(actor, "is caught in a construction zone", mlp);
 	    continue;
-	case NAV_NONE:
-	case NAV_CANAL:
-	    shp_stays(actor, "is landlocked", mlp);
-	    continue;
-	case NAVOK:
-	    break;
 	default:
 	    CANT_REACH();
-	    shp_stays(actor, "was just swallowed by a big green worm", mlp);
+	    /* fall through */
+	case SHP_STUCK_CANAL:
+	case SHP_STUCK_IMPASSABLE:
+	    shp_stays(actor, "is landlocked", mlp);
 	    continue;
 	}
 	if (first) {
@@ -321,41 +319,34 @@ shp_stays(natid actor, char *str, struct ulist *mlp)
 }
 
 /*
- * Can SP navigate in SECTP?
+ * Return whether and why SP would be stuck in SECTP.
- * Sector ownership is *not* considered!
- * Return NAVOK when yes.
- * Return NAV_02 when it could if the sector was at least 2% efficient.
- * Return NAV_60 when it could if the sector was at least 60% efficient.
- * Return NAV_CANAL when it lacks capability M_CANAL.
- * Return NAV_NONE when this sector type isn't navigable at all.
  */
-enum d_navigation
+enum shp_stuck
 shp_check_nav(struct shpstr *sp, struct sctstr *sectp)
 {
     switch (dchr[sectp->sct_type].d_nav) {
     case NAVOK:
 	break;
     case NAV_CANAL:
-	if (mchr[sp->shp_type].m_flags & M_CANAL) {
+	if (!(mchr[sp->shp_type].m_flags & M_CANAL)) {
-	    if (sectp->sct_effic < 2)
+	    return SHP_STUCK_CANAL;
-		return NAV_02;
+	}
-	} else
+	/* fall through */
-	    return NAV_CANAL;
-	break;
     case NAV_02:
 	if (sectp->sct_effic < 2)
-	    return NAV_02;
+	    return SHP_STUCK_CONSTRUCTION;
 	break;
     case NAV_60:
 	if (sectp->sct_effic < 60)
-	    return NAV_60;
+	    return SHP_STUCK_CONSTRUCTION;
 	break;
     default:
 	CANT_REACH();
+	/* fall through */
     case NAV_NONE:
-	return NAV_NONE;
+	return SHP_STUCK_IMPASSABLE;
     }
-    return NAVOK;
+    return SHP_STUCK_NOT;
 }
 
 int
@@ -771,10 +762,10 @@ shp_nav_one_sector(struct emp_qelem *list, int dir, natid actor,
     coord newx;
     coord newy;
     int move;
+    enum shp_stuck stuck;
     int stopping = 0;
     double mobcost;
     char dp[80];
-    int navigate;
 
     if (dir <= DIR_STOP || dir >= DIR_VIEW) {
 	shp_nav_put(list, actor);
@@ -790,8 +781,8 @@ shp_nav_one_sector(struct emp_qelem *list, int dir, natid actor,
 	newx = xnorm(mlp->unit.ship.shp_x + dx);
 	newy = ynorm(mlp->unit.ship.shp_y + dy);
 	getsect(newx, newy, &sect);
-	navigate = shp_check_nav(&mlp->unit.ship, &sect);
+	stuck = shp_check_nav(&mlp->unit.ship, &sect);
-	if (navigate == NAVOK &&
+	if (stuck == SHP_STUCK_NOT &&
 	    (!sect.sct_own
 	     || relations_with(sect.sct_own, actor) >= FRIENDLY))
 	    move = 1;
@@ -803,11 +794,11 @@ shp_nav_one_sector(struct emp_qelem *list, int dir, natid actor,
 	newx = xnorm(mlp->unit.ship.shp_x + dx);
 	newy = ynorm(mlp->unit.ship.shp_y + dy);
 	getsect(newx, newy, &sect);
-	navigate = shp_check_nav(&mlp->unit.ship, &sect);
+	stuck = shp_check_nav(&mlp->unit.ship, &sect);
-	if (navigate != NAVOK ||
+	if (stuck != SHP_STUCK_NOT ||
 	    (sect.sct_own
 	     && relations_with(sect.sct_own, actor) < FRIENDLY)) {
-	    if (navigate == NAV_CANAL)
+	    if (stuck == SHP_STUCK_CANAL)
 		sprintf(dp,
 			"is too large to fit into the canal system at %s",
 			xyas(newx, newy, actor));