fixed bug with random calls

There also seemed to be a bug with the shuffling of opening positions; I had changed the declaration of the position number from long long int to u64 to comply with MSVC, but this suppressed shuffling completely. I now changed it to int. I recently noted a problem with true randomizing anyway: this was based on srand(time()), but time() apparently did not change fast enough, so that starting several games in rapid succession (because the book line contained a 3-fold repetition) produced identical games. So I now seed the random once and for all during startup, based on the msec of the time mark, and removed the other calls to srand().

diff --git a/backend.c b/backend.c
index 711d1e0..891d3e0 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -619,6 +619,7 @@ InitBackEnd1()
     ShowThinkingEvent(); // [HGM] thinking: make sure post/nopost state is set according to options\r
 \r
     GetTimeMark(&programStartTime);\r
+    srand(programStartTime.ms); // [HGM] book: makes sure random is unpredictabe to msec level\r
 \r
     ClearProgramStats();\r
     programStats.ok_to_send = 1;\r
@@ -4255,106 +4256,7 @@ ParseOneMove(move, moveNum, moveType, fromX, fromY, toX, toY, promoChar)
     }\r
 }\r
 \r
-#if 0\r
-/* [AS] FRC game initialization */\r
-static int FindEmptySquare( Board board, int n )\r
-{\r
-    int i = 0;\r
-\r
-    while( 1 ) {\r
-        while( board[0][i] != EmptySquare ) i++;\r
-        if( n == 0 )\r
-            break;\r
-        n--;\r
-        i++;\r
-    }\r
-\r
-    return i;\r
-}\r
-\r
-static void ShuffleFRC( Board board )\r
-{\r
-    int i;\r
-\r
-    srand( time(0) );\r
-    \r
-    for( i=0; i<8; i++ ) {\r
-        board[0][i] = EmptySquare;\r
-    }\r
-\r
-    board[0][(rand() % 4)*2  ] = WhiteBishop; /* On dark square */\r
-    board[0][(rand() % 4)*2+1] = WhiteBishop; /* On lite square */\r
-    board[0][FindEmptySquare(board, rand() % 6)] = WhiteQueen;\r
-    board[0][FindEmptySquare(board, rand() % 5)] = WhiteKnight;\r
-    board[0][FindEmptySquare(board, rand() % 4)] = WhiteKnight;\r
-    board[0][ i=FindEmptySquare(board, 0) ] = WhiteRook;\r
-    initialRights[1]  = initialRights[4]  =\r
-    castlingRights[0][1] = castlingRights[0][4] = i;\r
-    board[0][ i=FindEmptySquare(board, 0) ] = WhiteKing;\r
-    initialRights[2]  = initialRights[5]  =\r
-    castlingRights[0][2] = castlingRights[0][5] = i;\r
-    board[0][ i=FindEmptySquare(board, 0) ] = WhiteRook;\r
-    initialRights[0]  = initialRights[3]  =\r
-    castlingRights[0][0] = castlingRights[0][3] = i;\r
-\r
-    for( i=BOARD_LEFT; i<BOARD_RGHT; i++ ) {\r
-        board[BOARD_HEIGHT-1][i] = board[0][i] + BlackPawn - WhitePawn;\r
-    }\r
-}\r
-\r
-static unsigned char FRC_KnightTable[10] = {\r
-    0x00, 0x01, 0x02, 0x03, 0x11, 0x12, 0x13, 0x22, 0x23, 0x33\r
-};\r
-\r
-static void SetupFRC( Board board, int pos_index )\r
-{\r
-    int i;\r
-    unsigned char knights;\r
-\r
-    /* Bring the position index into a safe range (just in case...) */\r
-    if( pos_index < 0 ) pos_index = 0;\r
-\r
-    pos_index %= 960;\r
-\r
-    /* Clear the board */\r
-    for( i=0; i<8; i++ ) {\r
-        board[0][i] = EmptySquare;\r
-    }\r
-\r
-    /* Place bishops and queen */\r
-    board[0][ (pos_index % 4)*2 + 1 ] = WhiteBishop; /* On lite square */\r
-    pos_index /= 4;\r
-    \r
-    board[0][ (pos_index % 4)*2     ] = WhiteBishop; /* On dark square */\r
-    pos_index /= 4;\r
-\r
-    board[0][ FindEmptySquare(board, pos_index % 6) ] = WhiteQueen;\r
-    pos_index /= 6;\r
-\r
-    /* Place knigths */\r
-    knights = FRC_KnightTable[ pos_index ];\r
-\r
-    board[0][ FindEmptySquare(board, knights / 16) ] = WhiteKnight;\r
-    board[0][ FindEmptySquare(board, knights % 16) ] = WhiteKnight;\r
-\r
-    /* Place rooks and king */\r
-    board[0][ i=FindEmptySquare(board, 0) ] = WhiteRook;\r
-    initialRights[1]  = initialRights[4]  =\r
-    castlingRights[0][1] = castlingRights[0][4] = i;\r
-    board[0][ i=FindEmptySquare(board, 0) ] = WhiteKing;\r
-    initialRights[2]  = initialRights[5]  =\r
-    castlingRights[0][2] = castlingRights[0][5] = i;\r
-    board[0][ i=FindEmptySquare(board, 0) ] = WhiteRook;\r
-    initialRights[0]  = initialRights[3]  =\r
-    castlingRights[0][0] = castlingRights[0][3] = i;\r
-\r
-    /* Mirror piece placement for black */\r
-    for( i=BOARD_LEFT; i<BOARD_RGHT; i++ ) {\r
-        board[BOARD_HEIGHT-1][i] = board[0][i] + BlackPawn - WhitePawn;\r
-    }\r
-}\r
-#else\r
-// [HGM] shuffle: a more general way to suffle opening setups, applicable to arbitrry variants.\r
+// [HGM] shuffle: a general way to suffle opening setups, applicable to arbitrary variants.\r
 // All positions will have equal probability, but the current method will not provide a unique\r
 // numbering scheme for arrays that contain 3 or more pieces of the same kind.\r
 #define DARK 1\r
@@ -4363,7 +4265,7 @@ static void SetupFRC( Board board, int pos_index )
 \r
 int squaresLeft[4];\r
 int piecesLeft[(int)BlackPawn];\r
-u64 seed, nrOfShuffles;\r
+int seed, nrOfShuffles;\r
 \r
 void GetPositionNumber()\r
 {      // sets global variable seed\r
@@ -4371,7 +4273,6 @@ void GetPositionNumber()
 \r
        seed = appData.defaultFrcPosition;\r
        if(seed < 0) { // randomize based on time for negative FRC position numbers\r
-               srandom(time(0)); \r
                for(i=0; i<50; i++) seed += random();\r
                seed = random() ^ random() >> 8 ^ random() << 8;\r
                if(seed<0) seed = -seed;\r
@@ -4510,8 +4411,6 @@ void SetUpShuffle(Board board, int number)
        if(number >= 0) appData.defaultFrcPosition %= nrOfShuffles; // normalize\r
 }\r
 \r
-#endif\r
-\r
 int SetCharTable( char *table, const char * map )\r
 /* [HGM] moved here from winboard.c because of its general usefulness */\r
 /*       Basically a safe strcpy that uses the last character as King */\r

diff --git a/book.c b/book.c
index 124344f..2ec8546 100644 (file)
--- a/book.c
+++ b/book.c
@@ -500,7 +500,6 @@ char *ProbeBook(int moveNr, char *book)
     for(i=0; i<count; i++){
         total_weight += entries[i].weight;
     }
-    srandom( time(0) );
     j = (random() & 0x7FFF) * total_weight >> 15; // create random < total_weight
     total_weight = 0;
     for(i=0; i<count; i++){