[gnugo-devel] breakin and readconnect fixes

[Arend Bayer]

> Arend wrote:
> > Btw, Paul, I tried to get on good terms with your change of the connection
> > queue logic (only storing the origin instead of each stone of a string)
> > and failed badly. So I hope you won't be too upset in case I revert that
> > change soon...

I still don't like it very much (as it transforms each loop over every
intersection in the connection queue into a double loop) but...

> I would like to see profiles before and after, btw.

...you seem to have a point here. (My reverting patch caused about 2%
performance penalty, I didn't investigate very closely.)

So instead of reverting your change, here is a patch with 3 fixes, two
of them resolving issues caused by your patch:

1. Ladder attack against "secondary target" in break-in reading only
makes sense in block_off reading (unrelated).

2. add_to_start_queue must be called with string origin.

3. Allow for strings to be partially in the break-in goal.

Arend

- fixes for breakin and connection reading

Index: engine/readconnect.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/readconnect.c,v
retrieving revision 1.70
diff -u -p -r1.70 readconnect.c
--- engine/readconnect.c        11 Feb 2004 12:36:27 -0000      1.70
+++ engine/readconnect.c        24 Mar 2004 15:24:06 -0000
@@ -2753,12 +2753,21 @@ find_break_moves(int str, const char goa

   compute_connection_distances(str, NO_MOVE, 2.501, &conn1, 1);
   for (k = 0; k < conn1.queue_end; k++)
-    if (goal[conn1.queue[k]]
-       && board[conn1.queue[k]] == color) {
-      str2 = conn1.queue[k];
-      TRACE("%oUsing %1m as secondary target.\n", str2);
-      mark_string(str2, breakin_shadow, 1);
-      break;
+    if (board[conn1.queue[k]] == color) {
+      int stones[MAX_BOARD * MAX_BOARD];
+      int num_stones = findstones(conn1.queue[k],
+                                 MAX_BOARD * MAX_BOARD, stones);
+      int i;
+      for (i = 0; i < num_stones; i++) {
+       if (goal[stones[i]]) {
+         str2 = find_origin(stones[i]);
+         TRACE("%oUsing %1m as secondary target.\n", str2);
+         mark_string(str2, breakin_shadow, 1);
+         break;
+       }
+      }
+      if (i < num_stones)
+       break;
     }

   /* Add all stones in the goal to the queue. */
@@ -2802,7 +2811,7 @@ find_break_moves(int str, const char goa
                                      moves, *total_distance, cutoff);
   }

-  {
+  if (color_to_move != board[str]) {
     int move;
     if (num_moves < MAX_MOVES
        && ON_BOARD(str2)
@@ -2810,6 +2819,7 @@ find_break_moves(int str, const char goa
       moves[num_moves++] = move;
     }
   }
+
   for (k = 0; k < num_moves; k++)
     breakin_shadow[moves[k]] = 1;

@@ -4093,7 +4103,7 @@ compute_connection_distances(int str, in
   clear_connection_data(conn);

   /* Add the origin of the initial string to the queue. */
-  add_to_start_queue(str, 0.0, conn);
+  add_to_start_queue(find_origin(str), 0.0, conn);

   conn->target = target;
   conn->cutoff_distance = cutoff;