add bitScanReverse; bitboardRooks

bitboard.cpp

@@ -2,13 +2,8 @@
 
 /*bitwise operations*/
 namespace bitwise {
-int BitScanForward(U64 bb) {
-	/**
-	 * returns the index of LSB between [0,63]
-	 * adapted by CPW, original by @author Kim Walisch (2012)
-	 */
-	if (!bb) throw std::domain_error("Bitboard is empty");
-    const int index64[64] = {
+
+const int index64[64] = {
    		 0, 47,  1, 56, 48, 27,  2, 60,
    		57, 49, 41, 37, 28, 16,  3, 61,
 		54, 58, 35, 52, 50, 42, 21, 44,
@@ -19,44 +14,77 @@ int BitScanForward(U64 bb) {
 		13, 18,  8, 12,  7,  6,  5, 63
 	};
 
+int bitScanForward(U64 bb) {
+	/**
+	 * returns the index of LSB between [0,63]
+	 * adapted by CPW, original by @author Kim Walisch (2012)
+	 */
+	if (!bb) throw std::domain_error("Bitboard is empty");
+
     const U64 debruijn64 = C64(0x03f79d71b4cb0a89);
     return index64[((bb ^ (bb-1)) * debruijn64) >> 58];
 }
 
+int bitScanReverse(U64 bb) {
+    /**
+	 * returns the index of MSB between [0,63]
+	 * adapted by CPW, original by @author Kim Walisch (2012)
+	 */
+    if (!bb) throw std::domain_error("Bitboard is empty");
+
+    bb |= bb >> 1; 
+    bb |= bb >> 2;
+    bb |= bb >> 4;
+    bb |= bb >> 8;
+    bb |= bb >> 16;
+    bb |= bb >> 32;
+    const U64 debruijn64 = C64(0x03f79d71b4cb0a89);
+    return index64[(bb * debruijn64) >> 58];
+}
+
+
 std::list<int> extractIndexes(U64 bb) {
     std::list<int> myList;
 	while (bb) {
-		myList.push_back(BitScanForward(bb));
+		myList.push_back(bitScanForward(bb));
 		bb &= bb-1; //reset LSB
 	}
 	return myList;
 }
 
+void printBitboard(std::ostream &out, U64 bb){
+    for (int rank = 7; rank >= 0; rank--) {
+        for (int file = 0; file < 8; file++) {
+            int index = rank*8+file;
+            if (bb & (1ULL << index)) out << "1 ";
+                else out << "0 ";
+        }
+        out << "\n";
+    }
+}
+
 } //namespace bitwise 
 
 
 Bitboard::Bitboard(U64 dec) {
     bb = dec;
 }
 
-int Bitboard::BitScanForward() {
-    return bitwise::BitScanForward(bb);
+int Bitboard::bitScanForward() {
+    return bitwise::bitScanForward(bb);
+}
+
+int Bitboard::bitScanReverse() {
+    return bitwise::bitScanReverse(bb);
 }
 
-void Bitboard::printNumber() const{
+void Bitboard::printNumber() const {
     std::cout << bb;
     return;
 }
 
 std::ostream& operator<<(std::ostream &out, const Bitboard board){
-    for (int rank = 7; rank >= 0; rank--) {
-        for (int file = 0; file < 8; file++) {
-            int index = rank*8+file;
-            if (board.bb & (1ULL << index)) out << "1 ";
-                else out << "0 ";
-        }
-        out << "\n";
-    }
+    bitwise::printBitboard(out, board.bb);
     return out;
 }
 
@@ -70,8 +98,9 @@ Bitboard Bitboard::getComplement() const {
 
 void Bitboard::bitToggle(int index) {
     bb ^= (1ULL << index);
-    return ;
+    return;
 }
+
 std::list<int> Bitboard::extractIndexes() const {
 	return bitwise::extractIndexes(bb);
 }

bitboard.hpp

@@ -16,7 +16,8 @@ class Bitboard {
         friend std::ostream& operator<<(std::ostream &out, Bitboard bit); //prints as chessboard
         void printNumber() const;                                               //prints number
         bool empty() const;
-        int BitScanForward();
+        int bitScanForward();
+        int bitScanReverse();
     protected:
         U64 bb; //bitboard 64bit
         static const U64 notAFile = 0xfefefefefefefefe;