Fix PV sorting during fail low

When an engine reports a fail low as thinking output, and then re-searches
the same move with larger window, it now gets a lower score. This line
would then be sorted below the earlier fail low, because it was mistaken
for a multi-PV line for an inferior move. This patch suppresses PVs
overtaking each other if they start with the same move.

diff --git a/engineoutput.c b/engineoutput.c
index 2b82948..d881ad0 100644 (file)
--- a/engineoutput.c
+++ b/engineoutput.c
@@ -74,6 +74,7 @@ typedef struct {
     char * hint;
     int an_move_index;
     int an_move_count;
+    int moveKey;
 } EngineOutputData;
 
 // called by other front-end
@@ -91,7 +92,7 @@ static char lastLine[2][MSG_SIZ];
 static char header[MSG_SIZ];
 
 #define MAX_VAR 400
-static int scores[MAX_VAR], textEnd[MAX_VAR], curDepth[2], nrVariations[2];
+static int scores[MAX_VAR], textEnd[MAX_VAR], keys[MAX_VAR], curDepth[2], nrVariations[2];
 
 extern int initialRulePlies;
 
@@ -161,6 +162,9 @@ SetProgramStats (FrontEndProgramStats * stats) // now directly called by back-en
     EngineOutputData ed;
     int clearMemo = FALSE;
     int which, depth, multi;
+    ChessMove moveType;
+    int ff, ft, rf, rt;
+    char pc;
 
     if( stats == 0 ) {
         SetEngineState( 0, STATE_IDLE, "" );
@@ -234,6 +238,10 @@ SetProgramStats (FrontEndProgramStats * stats) // now directly called by back-en
         }
     }
 
+    if(ParseOneMove(ed.pv, currentMove, &moveType, &ff, &rf, &ft, &rt, &pc))
+       ed.moveKey = (ff<<24 | rf << 16 | ft << 8 | rt) ^ pc*87161;
+    else ed.moveKey = ed.nodes; // kludge to get unique key unlikely to match any move
+
     /* Update */
     lastDepth[which] = depth == 1 && ed.nodes == 0 ? 0 : depth; // [HGM] info-line kudge
     lastForwardMostMove[which] = forwardMostMove;
@@ -398,10 +406,13 @@ InsertionPoint (int len, EngineOutputData *ed)
                offs = textEnd[i+n];
                textEnd[i+n+2] = offs + len;
                scores[i+n+2] = newScore;
-               if(newScore < scores[i+n]) break;
+               keys[i+n+2] = ed->moveKey;
+               if(ed->moveKey != keys[i+n] && // same move always tops previous one (as a higher score must be a fail low)
+                  newScore < scores[i+n]) break;
                // if it had higher score as previous, move previous in stead
                scores[i+n+2] = scores[i+n];
                textEnd[i+n+2] = textEnd[i+n] + len;
+               keys[i+n+2] = keys[i+n];
        }
        if(i<0) {
                offs = 0;