Drawbridge jams

include/extern.h

@@ -320,11 +320,13 @@ extern boolean is_open_air(int, int);
 extern schar db_under_typ(int);
 extern int is_drawbridge_wall(int, int);
 extern boolean is_db_wall(int, int);
+extern boolean is_jammed_db(int, int);
 extern boolean find_drawbridge(int *, int *);
 extern boolean create_drawbridge(int, int, int, boolean);
 extern void open_drawbridge(int, int);
 extern void close_drawbridge(int, int);
 extern void destroy_drawbridge(int, int);
+extern int unjam_drawbridge(int, int);
 
 /* ### decl.c ### */
 

include/rm.h

@@ -192,20 +192,22 @@ enum door_states {
 /*
  * The four directions for a DrawBridge.
  */
-#define DB_NORTH 0
-#define DB_SOUTH 1
-#define DB_EAST 2
-#define DB_WEST 3
-#define DB_DIR 3 /* mask for direction */
+#define DB_NORTH 0x0
+#define DB_SOUTH 0x1
+#define DB_EAST  0x2
+#define DB_WEST  0x3
+#define DB_DIR   0x3 /* mask for direction */
 
 /*
  * What's under a drawbridge.
  */
-#define DB_MOAT 0
-#define DB_LAVA 4
-#define DB_ICE 8
-#define DB_FLOOR 16
-#define DB_UNDER 28 /* mask for underneath */
+#define DB_MOAT  0x0
+#define DB_LAVA  0x4
+#define DB_ICE   0x8
+#define DB_FLOOR 0xc
+#define DB_UNDER 0xc /* mask for underneath */
+
+#define DB_JAM   0x10
 
 /*
  * Wall information.  Nondiggable also applies to iron bars.

src/dbridge.c

@@ -181,6 +181,15 @@ is_db_wall(int x, int y)
     return (boolean) (levl[x][y].typ == DBWALL);
 }
 
+boolean
+is_jammed_db(int x, int y)
+{
+    if (!find_drawbridge(&x, &y))
+        return FALSE;
+    else
+        return ((levl[x][y].drawbridgemask & DB_JAM) != 0);
+}
+
 /*
  * Return true with x,y pointing to the drawbridge if x,y initially indicate
  * a drawbridge or drawbridge wall.
@@ -974,4 +983,45 @@ destroy_drawbridge(int x, int y)
     nokiller();
 }
 
+int
+unjam_drawbridge(int x, int y)
+{
+    boolean under_u = (!u.dx && !u.dy);
+    struct monst *mtmp = m_at(x, y);
+
+    if (!is_jammed_db(x, y)) {
+        impossible("unjam_drawbridge: clearing nonexistant jam?");
+        return 0;
+    }
+
+    if (mtmp) {
+        pline("%s is in the way.", Monnam(mtmp));
+        return 0;
+    }
+    if (sobj_at(BOULDER, x, y) && !Passes_walls && !under_u) {
+        There("is a boulder in your way.");
+        return 0;
+    }
+    /* duplicate tight-space checks from test_move */
+    if (u.dx && u.dy && bad_rock(g.youmonst.data, u.ux, y)
+        && bad_rock(g.youmonst.data, x, u.uy)) {
+        if ((g.invent && (inv_weight() + weight_cap() > 600))
+            || bigmonst(g.youmonst.data)) {
+            /* don't allow untrap if they can't get thru to it */
+            You("are unable to reach the mechanism!");
+            return 0;
+        }
+    }
+    if (rn2(3)) {
+        You("are having a difficult time clearing the jam.");
+        return 1;
+    }
+
+    /* ok, disarm it. */
+    You("unjam the mechanism.");
+    (void) find_drawbridge(&x, &y);
+    levl[x][y].drawbridgemask &= ~DB_JAM;
+    return 1;
+}
+
 /*dbridge.c*/

src/music.c

@@ -757,14 +757,12 @@ do_play_instrument(struct obj* instr)
                             u.uevent.uheard_tune = 2;
                             record_achievement(ACH_TUNE);
                             if (levl[x][y].typ == DRAWBRIDGE_DOWN) {
-                                if (!rn2(5)) {
-                                    /* Future improvement: if flags is ever
-                                     * expanded beyond 5 bits, could set a bit
-                                     * here to make the mechanism continue to be
-                                     * stuck until some condition is met, such
-                                     * as opening/closing magic used on it */
-                                    pline("The mechanism seems to get jammed.");
+                                boolean jammed = is_jammed_db(x, y);
+                                if (!rn2(5) || jammed) {
+                                    pline("The mechanism seems to %s jammed.",
+                                          jammed ? "be" : "get");
                                     pline("It won't close.");
+                                    levl[x][y].drawbridgemask |= DB_JAM;
                                     return ECMD_TIME;
                                 }
                                 close_drawbridge(x, y);

src/trap.c

@@ -5449,7 +5449,10 @@ untrap(
                     return 0;
                 }
             }
-        } /* end if */
+        }
+        else if (is_jammed_db(x, y)) {
+            return unjam_drawbridge(x, y);
+        }
 
         if (boxcnt) {
             /* 3.7: this used to allow searching for traps on multiple