Support UCI ponder

src/search.c

@@ -63,6 +63,10 @@ void InitPruningAndReductionTables() {
   }
 }
 
+INLINE int StopSearch(SearchParams* params) {
+  return params->timeset && GetTimeMS() - params->start > min(params->alloc, params->max) && !params->pondering;
+}
+
 void* UCISearch(void* arg) {
   SearchArgs* args = (SearchArgs*)arg;
 
@@ -80,8 +84,14 @@ void* UCISearch(void* arg) {
 void BestMove(Board* board, SearchParams* params, ThreadData* threads, SearchResults* results) {
   Move bestMove;
   if ((bestMove = TBRootProbe(board))) {
+    while (params->pondering)
+      asm("");
+
     printf("bestmove %s\n", MoveToStr(bestMove));
   } else if ((bestMove = ProbeNoob(board))) {
+    while (params->pondering)
+      asm("");
+
     printf("bestmove %s\n", MoveToStr(bestMove));
   } else {
     pthread_t pthreads[threads->count];
@@ -100,7 +110,14 @@ void BestMove(Board* board, SearchParams* params, ThreadData* threads, SearchRes
     for (int i = 1; i < threads->count; i++)
       pthread_join(pthreads[i], NULL);
 
-    printf("bestmove %s\n", MoveToStr(results->bestMoves[results->depth]));
+    while (params->pondering)
+      asm("");
+
+    printf("bestmove %s", MoveToStr(results->bestMoves[results->depth]));
+    if (results->ponderMoves[results->depth])
+      printf(" ponder %s", MoveToStr(results->ponderMoves[results->depth]));
+
+    printf("\n");
   }
 }
 
@@ -204,6 +221,7 @@ void* Search(void* arg) {
       results->depth = depth;
       results->scores[depth] = thread->scores[0];
       results->bestMoves[depth] = thread->bestMoves[0];
+      results->ponderMoves[depth] = thread->pvs[0].count > 1 ? thread->pvs[0].moves[1] : NULL_MOVE;
 
       if (!mainThread || depth < 5 || !params->timeset)
         continue;
@@ -257,8 +275,7 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
   // Either mainthread has ended us OR we've run out of time
   // this second check is more expensive and done only every 1024 nodes
   // 1Mnps ~1ms
-  if (params->stopped ||
-      (!(data->nodes & 1023) && params->timeset && GetTimeMS() - params->start > min(params->alloc, params->max)))
+  if (params->stopped || (!(data->nodes & 1023) && StopSearch(params)))
     longjmp(thread->exit, 1);
 
   if (!isRoot) {
@@ -610,8 +627,7 @@ int Quiesce(int alpha, int beta, ThreadData* thread, PV* pv) {
   // Either mainthread has ended us OR we've run out of time
   // this second check is more expensive and done only every 1024 nodes
   // 1Mnps ~1ms
-  if (params->stopped ||
-      (!(data->nodes & 1023) && params->timeset && GetTimeMS() - params->start > min(params->alloc, params->max)))
+  if (params->stopped || (!(data->nodes & 1023) && StopSearch(params)))
     longjmp(thread->exit, 1);
 
   // draw check

src/search.h

@@ -47,7 +47,7 @@ int Quiesce(int alpha, int beta, ThreadData* thread, PV* pv);
 
 void PrintInfo(PV* pv, int score, ThreadData* thread, int alpha, int beta, int multiPV);
 void PrintPV(PV* pv);
-
+ 
 int MoveSearchedByMultiPV(ThreadData* thread, Move move);
 int MoveSearchable(SearchParams* params, Move move);
 

src/types.h

@@ -202,6 +202,7 @@ typedef struct {
   int movesToGo;
   int stopped;
   int quit;
+  int pondering;
   int multiPV;
   int searchMoves;
   SimpleMoveList searchable;
@@ -211,6 +212,7 @@ typedef struct {
   int depth;
   Score scores[MAX_SEARCH_PLY];
   Move bestMoves[MAX_SEARCH_PLY];
+  Move ponderMoves[MAX_SEARCH_PLY];
 } SearchResults;
 
 typedef struct {

src/uci.c

@@ -64,6 +64,7 @@ void ParseGo(char* in, SearchParams* params, Board* board, ThreadData* threads)
   params->stopped = 0;
   params->quit = 0;
   params->multiPV = MULTI_PV;
+  params->pondering = 0;
   params->searchMoves = 0;
   params->searchable.count = 0;
 
@@ -97,6 +98,9 @@ void ParseGo(char* in, SearchParams* params, Board* board, ThreadData* threads)
   if ((ptrChar = strstr(in, "depth")))
     depth = min(MAX_SEARCH_PLY - 1, atoi(ptrChar + 6));
 
+  if ((ptrChar = strstr(in, "ponder")))
+    params->pondering = 1;
+
   if ((ptrChar = strstr(in, "searchmoves"))) {
     params->searchMoves = 1;
 
@@ -243,12 +247,16 @@ void UCILoop() {
     } else if (!strncmp(in, "go", 2)) {
       ParseGo(in, &searchParameters, &board, threads);
     } else if (!strncmp(in, "stop", 4)) {
+      searchParameters.pondering = 0;
       searchParameters.stopped = 1;
     } else if (!strncmp(in, "quit", 4)) {
+      searchParameters.pondering = 0;
       searchParameters.quit = 1;
       break;
     } else if (!strncmp(in, "uci", 3)) {
       PrintUCIOptions();
+    } else if (!strncmp(in, "ponderhit", 9)) {
+      searchParameters.pondering = 0;
     } else if (!strncmp(in, "board", 5)) {
       PrintBoard(&board);
     } else if (!strncmp(in, "eval", 4)) {