Fix GameListHighlight WB

The routine to highlight a game line in the Game List listbox of WinBoard
used an extremely inefficient linear search to find the game amongst the
selected games. This has now been replaced by bisection, after finding
an upper limit to the number of entries in the listbox by doubling
a trial size.

diff --git a/winboard/wgamelist.c b/winboard/wgamelist.c
index 17e78f1..196c837 100644 (file)
--- a/winboard/wgamelist.c
+++ b/winboard/wgamelist.c
@@ -437,14 +437,22 @@ VOID GameListPopDown(void)
 VOID GameListHighlight(int index)\r
 {\r
   char buf[MSG_SIZ];\r
-  int i, res = 0;\r
+  int i, j, k, n, res = 0;\r
   if (gameListDialog == NULL) return;\r
-  for(i=0; res != LB_ERR; i++) {\r
+  for(i=64; ; i+=i) {\r
         res = SendDlgItemMessage( gameListDialog, OPT_GameListText, LB_GETTEXT, i, (LPARAM)buf );\r
-        if(index <= atoi( buf )) break;\r
+        if(res == LB_ERR || index < atoi( buf )) break;\r
   }\r
-  SendDlgItemMessage(gameListDialog, OPT_GameListText,\r
-    LB_SETCURSEL, i, 0);\r
+  j = i/2;\r
+  while(i-j > 1) {\r
+        n = (i + j) >> 1;\r
+        res = SendDlgItemMessage( gameListDialog, OPT_GameListText, LB_GETTEXT, n, (LPARAM)buf );\r
+        if(res == LB_ERR || index < (k = atoi( buf ))) i = n; else {\r
+            j = n;\r
+            if(index == k) break;\r
+        }\r
+  }\r
+  SendDlgItemMessage(gameListDialog, OPT_GameListText, LB_SETCURSEL, j, 0);\r
 }\r
 \r
 \r