Retire USE_COMPACT_ROOK_ATTACKS and USE_FOLDED_BITSCAN defines

This greatly simplifies bitboard.cpp that now has only two setups,
respectively for 32 and 64 bits CPU according to IS_64BIT define
that is automatically set but can be tweaked manually in
bitboard.h

No functional change both in 32 and in 64 bits.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/Readme.txt b/Readme.txt
index dc76d74227862c7bde9ddb643ad37775358568b6..0c6f5c7210bec5e62f17f3a12d40e77c78673151 100644 (file)
--- a/Readme.txt
+++ b/Readme.txt
@@ -45,7 +45,6 @@ PolyGlot documentation.  The book file can be selected by setting the
 UCI parameter "Book File".\r
 \r
 \r
-\r
 4. Compiling it yourself\r
 ------------------------\r
 \r
@@ -54,27 +53,9 @@ Stockfish directly from the source code with the included Makefile.
 The exception is computer with big-endian CPUs, like PowerPC\r
 Macintoshes. Some of the bitboard routines in the current version of\r
 Stockfish are endianness-sensitive, and won't work on a big-endian CPU.\r
-Ensuring that the line with #define USE_32BIT_ATTACKS" near the top\r
-of bitboard.h is commented out should solve this problem.\r
-Commenting out the line with "#define USE_32BIT_ATTACKS" near the\r
-\r
-There is also a problem with compiling Stockfish on certain 64-bit\r
-systems, regardless of the endianness.  If Stockfish segfaults\r
-immediately after startup, try to comment out the line with\r
-"#define USE_FOLDED_BITSCAN" near the beginning of bitboard.h and\r
-recompile.\r
-\r
-Finally, even if Stockfish does work without any changes on your\r
-computer, it might be possible to improve the performance by changing\r
-some of the #define directives in bitboard.h.  The default settings\r
-are optimized for 64-bit CPUs.  On 32-bit CPUs, it is probably better\r
-to switch on USE_32BIT_ATTACKS, and to use BITCOUNT_SWAR_32 instead of\r
-BITCOUNT_SWAR_64.  For computers with very little memory (like\r
-handheld devices), it is possible to conserve memory by defining\r
-USE_COMPACT_ROOK_ATTACKS.\r
-\r
-\r
-6. Terms of use\r
+\r
+\r
+5. Terms of use\r
 ---------------\r
 \r
 Stockfish is free, and distributed under the GNU General Public License\r
@@ -93,7 +74,7 @@ For full details, read the copy of the GPL found in the file named
 Copying.txt.\r
 \r
 \r
-7. Feedback\r
+6. Feedback\r
 -----------\r
 \r
 The author's e-mail address is mcostalba@gmail.com\r

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index a73c5a2dc7ad970d6c8f16275ead918d2af46ac1..ba03d66ef85669cfe4d9f3c8ddf3fa19e272d99c 100644 (file)
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -22,16 +22,6 @@
 //// Includes
 ////
 
-#ifdef _MSC_VER
-    #include <intrin.h>
-    #ifdef _WIN64
-        #pragma intrinsic(_BitScanForward64)
-    #else
-        #pragma intrinsic(_BitScanForward)
-    #endif
-    #define USING_INTRINSICS
-#endif
-
 #include <iostream>
 
 #include "bitboard.h"
@@ -39,46 +29,33 @@
 #include "direction.h"
 
 
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-
-Bitboard RankAttacks[8][64], FileAttacks[8][64];
-
-#elif defined(USE_32BIT_ATTACKS)
-
-const uint64_t RMult[64] = {
-  0xd7445cdec88002c0ULL, 0xd0a505c1f2001722ULL, 0xe065d1c896002182ULL,
-  0x9a8c41e75a000892ULL, 0x8900b10c89002aa8ULL, 0x9b28d1c1d60005a2ULL,
-  0x15d6c88de002d9aULL, 0xb1dbfc802e8016a9ULL, 0x149a1042d9d60029ULL,
-  0xb9c08050599e002fULL, 0x132208c3af300403ULL, 0xc1000ce2e9c50070ULL,
-  0x9d9aa13c99020012ULL, 0xb6b078daf71e0046ULL, 0x9d880182fb6e002eULL,
-  0x52889f467e850037ULL, 0xda6dc008d19a8480ULL, 0x468286034f902420ULL,
-  0x7140ac09dc54c020ULL, 0xd76ffffa39548808ULL, 0xea901c4141500808ULL,
-  0xc91004093f953a02ULL, 0x2882afa8f6bb402ULL, 0xaebe335692442c01ULL,
-  0xe904a22079fb91eULL, 0x13a514851055f606ULL, 0x76c782018c8fe632ULL,
-  0x1dc012a9d116da06ULL, 0x3c9e0037264fffa6ULL, 0x2036002853c6e4a2ULL,
-  0xe3fe08500afb47d4ULL, 0xf38af25c86b025c2ULL, 0xc0800e2182cf9a40ULL,
-  0x72002480d1f60673ULL, 0x2500200bae6e9b53ULL, 0xc60018c1eefca252ULL,
-  0x600590473e3608aULL, 0x46002c4ab3fe51b2ULL, 0xa200011486bcc8d2ULL,
-  0xb680078095784c63ULL, 0x2742002639bf11aeULL, 0xc7d60021a5bdb142ULL,
-  0xc8c04016bb83d820ULL, 0xbd520028123b4842ULL, 0x9d1600344ac2a832ULL,
-  0x6a808005631c8a05ULL, 0x604600a148d5389aULL, 0xe2e40103d40dea65ULL,
-  0x945b5a0087c62a81ULL, 0x12dc200cd82d28eULL, 0x2431c600b5f9ef76ULL,
-  0xfb142a006a9b314aULL, 0x6870e00a1c97d62ULL, 0x2a9db2004a2689a2ULL,
-  0xd3594600caf5d1a2ULL, 0xee0e4900439344a7ULL, 0x89c4d266ca25007aULL,
-  0x3e0013a2743f97e3ULL, 0x180e31a0431378aULL, 0x3a9e465a4d42a512ULL,
-  0x98d0a11a0c0d9cc2ULL, 0x8e711c1aba19b01eULL, 0x8dcdc836dd201142ULL,
-  0x5ac08a4735370479ULL,
-};
+#if defined(IS_64BIT)
 
-const int RShift[64] = {
-  20, 21, 21, 21, 21, 21, 21, 20, 21, 22, 22, 22, 22, 22, 22, 21,
-  21, 22, 22, 22, 22, 22, 22, 21, 21, 22, 22, 22, 22, 22, 22, 21,
-  21, 22, 22, 22, 22, 22, 22, 21, 21, 22, 22, 22, 22, 22, 22, 21,
-  21, 22, 22, 22, 22, 22, 22, 21, 20, 21, 21, 21, 21, 21, 21, 20
+const uint64_t BMult[64] = {
+  0x440049104032280ULL, 0x1021023c82008040ULL, 0x404040082000048ULL,
+  0x48c4440084048090ULL, 0x2801104026490000ULL, 0x4100880442040800ULL,
+  0x181011002e06040ULL, 0x9101004104200e00ULL, 0x1240848848310401ULL,
+  0x2000142828050024ULL, 0x1004024d5000ULL, 0x102044400800200ULL,
+  0x8108108820112000ULL, 0xa880818210c00046ULL, 0x4008008801082000ULL,
+  0x60882404049400ULL, 0x104402004240810ULL, 0xa002084250200ULL,
+  0x100b0880801100ULL, 0x4080201220101ULL, 0x44008080a00000ULL,
+  0x202200842000ULL, 0x5006004882d00808ULL, 0x200045080802ULL,
+  0x86100020200601ULL, 0xa802080a20112c02ULL, 0x80411218080900ULL,
+  0x200a0880080a0ULL, 0x9a01010000104000ULL, 0x28008003100080ULL,
+  0x211021004480417ULL, 0x401004188220806ULL, 0x825051400c2006ULL,
+  0x140c0210943000ULL, 0x242800300080ULL, 0xc2208120080200ULL,
+  0x2430008200002200ULL, 0x1010100112008040ULL, 0x8141050100020842ULL,
+  0x822081014405ULL, 0x800c049e40400804ULL, 0x4a0404028a000820ULL,
+  0x22060201041200ULL, 0x360904200840801ULL, 0x881a08208800400ULL,
+  0x60202c00400420ULL, 0x1204440086061400ULL, 0x8184042804040ULL,
+  0x64040315300400ULL, 0xc01008801090a00ULL, 0x808010401140c00ULL,
+  0x4004830c2020040ULL, 0x80005002020054ULL, 0x40000c14481a0490ULL,
+  0x10500101042048ULL, 0x1010100200424000ULL, 0x640901901040ULL,
+  0xa0201014840ULL, 0x840082aa011002ULL, 0x10010840084240aULL,
+  0x420400810420608ULL, 0x8d40230408102100ULL, 0x4a00200612222409ULL,
+  0xa08520292120600ULL
 };
 
-#else // if defined(USE_32BIT_ATTACKS)
-
 const uint64_t RMult[64] = {
   0xa8002c000108020ULL, 0x4440200140003000ULL, 0x8080200010011880ULL,
   0x380180080141000ULL, 0x1a00060008211044ULL, 0x410001000a0c0008ULL,
@@ -104,6 +81,13 @@ const uint64_t RMult[64] = {
   0x410201ce5c030092ULL
 };
 
+const int BShift[64] = {
+  58, 59, 59, 59, 59, 59, 59, 58, 59, 59, 59, 59, 59, 59, 59, 59,
+  59, 59, 57, 57, 57, 57, 59, 59, 59, 59, 57, 55, 55, 57, 59, 59,
+  59, 59, 57, 55, 55, 57, 59, 59, 59, 59, 57, 57, 57, 57, 59, 59,
+  59, 59, 59, 59, 59, 59, 59, 59, 58, 59, 59, 59, 59, 59, 59, 58
+};
+
 const int RShift[64] = {
   52, 53, 53, 53, 53, 53, 53, 52, 53, 54, 54, 54, 54, 54, 54, 53,
   53, 54, 54, 54, 54, 54, 54, 53, 53, 54, 54, 54, 54, 54, 54, 53,
@@ -111,15 +95,7 @@ const int RShift[64] = {
   53, 54, 54, 54, 54, 54, 54, 53, 52, 53, 53, 53, 53, 53, 53, 52
 };
 
-#endif // defined(USE_32BIT_ATTACKS)
-
-#if !defined(USE_COMPACT_ROOK_ATTACKS)
-Bitboard RMask[64];
-int RAttackIndex[64];
-Bitboard RAttacks[0x19000];
-#endif
-
-#if defined(USE_32BIT_ATTACKS)
+#else // if !defined(IS_64BIT)
 
 const uint64_t BMult[64] = {
   0x54142844c6a22981ULL, 0x710358a6ea25c19eULL, 0x704f746d63a4a8dcULL,
@@ -146,6 +122,31 @@ const uint64_t BMult[64] = {
   0xdc01f6dca4bebbdcULL,
 };
 
+const uint64_t RMult[64] = {
+  0xd7445cdec88002c0ULL, 0xd0a505c1f2001722ULL, 0xe065d1c896002182ULL,
+  0x9a8c41e75a000892ULL, 0x8900b10c89002aa8ULL, 0x9b28d1c1d60005a2ULL,
+  0x15d6c88de002d9aULL, 0xb1dbfc802e8016a9ULL, 0x149a1042d9d60029ULL,
+  0xb9c08050599e002fULL, 0x132208c3af300403ULL, 0xc1000ce2e9c50070ULL,
+  0x9d9aa13c99020012ULL, 0xb6b078daf71e0046ULL, 0x9d880182fb6e002eULL,
+  0x52889f467e850037ULL, 0xda6dc008d19a8480ULL, 0x468286034f902420ULL,
+  0x7140ac09dc54c020ULL, 0xd76ffffa39548808ULL, 0xea901c4141500808ULL,
+  0xc91004093f953a02ULL, 0x2882afa8f6bb402ULL, 0xaebe335692442c01ULL,
+  0xe904a22079fb91eULL, 0x13a514851055f606ULL, 0x76c782018c8fe632ULL,
+  0x1dc012a9d116da06ULL, 0x3c9e0037264fffa6ULL, 0x2036002853c6e4a2ULL,
+  0xe3fe08500afb47d4ULL, 0xf38af25c86b025c2ULL, 0xc0800e2182cf9a40ULL,
+  0x72002480d1f60673ULL, 0x2500200bae6e9b53ULL, 0xc60018c1eefca252ULL,
+  0x600590473e3608aULL, 0x46002c4ab3fe51b2ULL, 0xa200011486bcc8d2ULL,
+  0xb680078095784c63ULL, 0x2742002639bf11aeULL, 0xc7d60021a5bdb142ULL,
+  0xc8c04016bb83d820ULL, 0xbd520028123b4842ULL, 0x9d1600344ac2a832ULL,
+  0x6a808005631c8a05ULL, 0x604600a148d5389aULL, 0xe2e40103d40dea65ULL,
+  0x945b5a0087c62a81ULL, 0x12dc200cd82d28eULL, 0x2431c600b5f9ef76ULL,
+  0xfb142a006a9b314aULL, 0x6870e00a1c97d62ULL, 0x2a9db2004a2689a2ULL,
+  0xd3594600caf5d1a2ULL, 0xee0e4900439344a7ULL, 0x89c4d266ca25007aULL,
+  0x3e0013a2743f97e3ULL, 0x180e31a0431378aULL, 0x3a9e465a4d42a512ULL,
+  0x98d0a11a0c0d9cc2ULL, 0x8e711c1aba19b01eULL, 0x8dcdc836dd201142ULL,
+  0x5ac08a4735370479ULL,
+};
+
 const int BShift[64] = {
   26, 27, 27, 27, 27, 27, 27, 26, 27, 27, 27, 27, 27, 27, 27, 27,
   27, 27, 25, 25, 25, 25, 27, 27, 27, 27, 25, 23, 23, 25, 27, 27,
@@ -153,41 +154,19 @@ const int BShift[64] = {
   27, 27, 27, 27, 27, 27, 27, 27, 26, 27, 27, 27, 27, 27, 27, 26
 };
 
-#else // if defined(USE_32BIT_ATTACKS)
-
-const uint64_t BMult[64] = {
-  0x440049104032280ULL, 0x1021023c82008040ULL, 0x404040082000048ULL,
-  0x48c4440084048090ULL, 0x2801104026490000ULL, 0x4100880442040800ULL,
-  0x181011002e06040ULL, 0x9101004104200e00ULL, 0x1240848848310401ULL,
-  0x2000142828050024ULL, 0x1004024d5000ULL, 0x102044400800200ULL,
-  0x8108108820112000ULL, 0xa880818210c00046ULL, 0x4008008801082000ULL,
-  0x60882404049400ULL, 0x104402004240810ULL, 0xa002084250200ULL,
-  0x100b0880801100ULL, 0x4080201220101ULL, 0x44008080a00000ULL,
-  0x202200842000ULL, 0x5006004882d00808ULL, 0x200045080802ULL,
-  0x86100020200601ULL, 0xa802080a20112c02ULL, 0x80411218080900ULL,
-  0x200a0880080a0ULL, 0x9a01010000104000ULL, 0x28008003100080ULL,
-  0x211021004480417ULL, 0x401004188220806ULL, 0x825051400c2006ULL,
-  0x140c0210943000ULL, 0x242800300080ULL, 0xc2208120080200ULL,
-  0x2430008200002200ULL, 0x1010100112008040ULL, 0x8141050100020842ULL,
-  0x822081014405ULL, 0x800c049e40400804ULL, 0x4a0404028a000820ULL,
-  0x22060201041200ULL, 0x360904200840801ULL, 0x881a08208800400ULL,
-  0x60202c00400420ULL, 0x1204440086061400ULL, 0x8184042804040ULL,
-  0x64040315300400ULL, 0xc01008801090a00ULL, 0x808010401140c00ULL,
-  0x4004830c2020040ULL, 0x80005002020054ULL, 0x40000c14481a0490ULL,
-  0x10500101042048ULL, 0x1010100200424000ULL, 0x640901901040ULL,
-  0xa0201014840ULL, 0x840082aa011002ULL, 0x10010840084240aULL,
-  0x420400810420608ULL, 0x8d40230408102100ULL, 0x4a00200612222409ULL,
-  0xa08520292120600ULL
+const int RShift[64] = {
+  20, 21, 21, 21, 21, 21, 21, 20, 21, 22, 22, 22, 22, 22, 22, 21,
+  21, 22, 22, 22, 22, 22, 22, 21, 21, 22, 22, 22, 22, 22, 22, 21,
+  21, 22, 22, 22, 22, 22, 22, 21, 21, 22, 22, 22, 22, 22, 22, 21,
+  21, 22, 22, 22, 22, 22, 22, 21, 20, 21, 21, 21, 21, 21, 21, 20
 };
 
-const int BShift[64] = {
-  58, 59, 59, 59, 59, 59, 59, 58, 59, 59, 59, 59, 59, 59, 59, 59,
-  59, 59, 57, 57, 57, 57, 59, 59, 59, 59, 57, 55, 55, 57, 59, 59,
-  59, 59, 57, 55, 55, 57, 59, 59, 59, 59, 57, 57, 57, 57, 59, 59,
-  59, 59, 59, 59, 59, 59, 59, 59, 58, 59, 59, 59, 59, 59, 59, 58
-};
+#endif
+
 
-#endif // defined(USE_32BIT_ATTACKS)
+Bitboard RMask[64];
+int RAttackIndex[64];
+Bitboard RAttacks[0x19000];
 
 Bitboard BMask[64];
 int BAttackIndex[64];
@@ -226,9 +205,6 @@ namespace {
                             const int shift[2], const Bitboard mult[],
                             int deltas[][2]);
   void init_pseudo_attacks();
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-  void init_file_and_rank_attacks();
-#endif
 }
 
 
@@ -260,41 +236,25 @@ void init_bitboards() {
   init_ray_bitboards();
   init_attacks();
   init_between_bitboards();
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-  init_file_and_rank_attacks();
-#else
-  init_sliding_attacks(RAttacks, RAttackIndex, RMask, RShift,
-                       RMult, rookDeltas);
-#endif
-  init_sliding_attacks(BAttacks, BAttackIndex, BMask, BShift,
-                       BMult, bishopDeltas);
+  init_sliding_attacks(RAttacks, RAttackIndex, RMask, RShift, RMult, rookDeltas);
+  init_sliding_attacks(BAttacks, BAttackIndex, BMask, BShift, BMult, bishopDeltas);
   init_pseudo_attacks();
 }
 
 
-#if defined(USE_FOLDED_BITSCAN)
-
-static const int BitTable[64] = {
-  63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
-  51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52,
-  26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28,
-  58, 20, 37, 17, 36, 8
-};
-
+/// pop_1st_bit() finds and clears the least significant nonzero bit in a
+/// nonzero bitboard.
 
-/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
+#if defined(IS_64BIT)
 
-Square first_1(Bitboard b) {
-  b ^= (b - 1);
-  uint32_t fold = int(b) ^ int(b >> 32);
+Square pop_1st_bit(Bitboard *b) {
+  Bitboard bb = *b ^ (*b - 1);
+  uint32_t fold = int(bb) ^ int(bb >> 32);
+  *b &= (*b - 1);
   return Square(BitTable[(fold * 0x783a9b23) >> 26]);
 }
 
-
-/// pop_1st_bit() finds and clears the least significant nonzero bit in a
-/// nonzero bitboard.
-
-#if defined(USE_32BIT_ATTACKS)
+#else
 
 // Use type-punning
 union b_union {
@@ -329,46 +289,8 @@ Square pop_1st_bit(Bitboard *bb) {
   return Square(BitTable[(b * 0x783a9b23) >> 26]);
 }
 
-#else
-
-Square pop_1st_bit(Bitboard *b) {
-  Bitboard bb = *b ^ (*b - 1);
-  uint32_t fold = int(bb) ^ int(bb >> 32);
-  *b &= (*b - 1);
-  return Square(BitTable[(fold * 0x783a9b23) >> 26]);
-}
-
 #endif
 
-#else // defined(USE_FOLDED_BITSCAN)
-
-static const int BitTable[64] = {
-  0, 1, 2, 7, 3, 13, 8, 19, 4, 25, 14, 28, 9, 34, 20, 40, 5, 17, 26, 38, 15,
-  46, 29, 48, 10, 31, 35, 54, 21, 50, 41, 57, 63, 6, 12, 18, 24, 27, 33, 39,
-  16, 37, 45, 47, 30, 53, 49, 56, 62, 11, 23, 32, 36, 44, 52, 55, 61, 22, 43,
-  51, 60, 42, 59, 58
-};
-
-
-/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
-
-Square first_1(Bitboard b) {
-  return Square(BitTable[((b & -b) * 0x218a392cd3d5dbfULL) >> 58]);
-}
-
-
-/// pop_1st_bit() finds and clears the least significant nonzero bit in a
-/// nonzero bitboard.
-
-Square pop_1st_bit(Bitboard *b) {
-  Bitboard bb = *b;
-  *b &= (*b - 1);
-  return Square(BitTable[((bb & -bb) * 0x218a392cd3d5dbfULL) >> 58]);
-}
-
-#endif // defined(USE_FOLDED_BITSCAN)
-
-
 namespace {
 
   // All functions below are used to precompute various bitboards during
@@ -481,25 +403,25 @@ namespace {
       attackIndex[i] = index;
       mask[i] = sliding_attacks(i, 0ULL, 4, deltas, 1, 6, 1, 6);
 
-#if defined(USE_32BIT_ATTACKS)
-      j = (1 << (32 - shift[i]));
-#else
+#if defined(IS_64BIT)
       j = (1 << (64 - shift[i]));
+#else
+      j = (1 << (32 - shift[i]));
 #endif
 
       for(k = 0; k < j; k++) {
 
-#if defined(USE_32BIT_ATTACKS)
+#if defined(IS_64BIT)
+        b = index_to_bitboard(k, mask[i]);
+        attacks[index + ((b * mult[i]) >> shift[i])] =
+          sliding_attacks(i, b, 4, deltas);
+#else
         b = index_to_bitboard(k, mask[i]);
         attacks[index +
                  (unsigned(int(b) * int(mult[i]) ^
                            int(b >> 32) * int(mult[i] >> 32))
                   >> shift[i])] =
           sliding_attacks(i, b, 4, deltas);
-#else
-        b = index_to_bitboard(k, mask[i]);
-        attacks[index + ((b * mult[i]) >> shift[i])] =
-          sliding_attacks(i, b, 4, deltas);
 #endif
       }
       index += j;
@@ -516,29 +438,4 @@ namespace {
     }
   }
 
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-  void init_file_and_rank_attacks() {
-    int i, j, k, l, m, s;
-    Bitboard b1, b2;
-    for(i = 0; i < 64; i++) {
-
-      for(m = 0; m <= 1; m++) {
-        b1 = 0ULL;
-        for(j = 0; j < 6; j++) if(i & (1<<j)) b1 |= (1ULL << ((j+1)*(1+m*7)));
-        for(j = 0; j < 8; j++) {
-          b2 = 0ULL;
-          for(k = 0, s = 1; k < 2; k++, s *= -1) {
-            for(l = j+s; l >= 0 && l <= 7; l += s) {
-              b2 |= (m? RankBB[l] : FileBB[l]);
-              if(b1 & (1ULL << (l*(1+m*7)))) break;
-            }
-          }
-          if(m) FileAttacks[j][(b1*0xd6e8802041d0c441ULL) >> 58] = b2;
-          else RankAttacks[j][i] = b2;
-        }
-      }
-    }
-  }
-#endif // defined(USE_COMPACT_ROOK_ATTACKS)
-
 }

diff --git a/src/bitboard.h b/src/bitboard.h
index 54ed50538a2d3b960a37f48eb65a73ffca4e7ea3..3429c42ea02a0146fe05c767634ef346d7a96396 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -26,10 +26,6 @@
 //// Defines
 ////
 
-// Comment following define if you prefer manually adjust
-// platform macros defined below
-#define AUTO_CONFIGURATION
-
 // Quiet a warning on Intel compiler
 #if !defined(__SIZEOF_INT__ )
 #define __SIZEOF_INT__ 0
@@ -40,19 +36,6 @@
 #define IS_64BIT
 #endif
 
-#if !defined(AUTO_CONFIGURATION) || defined(IS_64BIT)
-
-//#define USE_COMPACT_ROOK_ATTACKS
-//#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-
-#else
-
-#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-
-#endif
-
 ////
 //// Includes
 ////
@@ -144,6 +127,13 @@ const Bitboard InFrontBB[2][8] = {
   }
 };
 
+const int BitTable[64] = {
+  63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
+  51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52,
+  26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28,
+  58, 20, 37, 17, 36, 8
+};
+
 extern Bitboard SetMaskBB[65];
 extern Bitboard ClearMaskBB[65];
 
@@ -154,20 +144,12 @@ extern Bitboard BetweenBB[64][64];
 extern Bitboard PassedPawnMask[2][64];
 extern Bitboard OutpostMask[2][64];
 
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-
-extern Bitboard RankAttacks[8][64], FileAttacks[8][64];
-
-#else
-
 extern const uint64_t RMult[64];
 extern const int RShift[64];
 extern Bitboard RMask[64];
 extern int RAttackIndex[64];
 extern Bitboard RAttacks[0x19000];
 
-#endif // defined(USE_COMPACT_ROOK_ATTACKS)
-
 extern const uint64_t BMult[64];
 extern const int BShift[64];
 extern Bitboard BMask[64];
@@ -303,29 +285,24 @@ inline Bitboard ray_bb(Square s, SignedDirection d) {
 }
 
 
-/// Functions for computing sliding attack bitboards.  rook_attacks_bb(),
+/// Functions for computing sliding attack bitboards. rook_attacks_bb(),
 /// bishop_attacks_bb() and queen_attacks_bb() all take a square and a
 /// bitboard of occupied squares as input, and return a bitboard representing
 /// all squares attacked by a rook, bishop or queen on the given square.
 
-#if defined(USE_COMPACT_ROOK_ATTACKS)
-
-inline Bitboard file_attacks_bb(Square s, Bitboard blockers) {
-  Bitboard b = (blockers >> square_file(s)) & 0x01010101010100ULL;
-  return
-    FileAttacks[square_rank(s)][(b*0xd6e8802041d0c441ULL)>>58] & file_bb(s);
-}
+#if defined(IS_64BIT)
 
-inline Bitboard rank_attacks_bb(Square s, Bitboard blockers) {
-  Bitboard b = (blockers >> ((s & 56) + 1)) & 63;
-  return RankAttacks[square_file(s)][b] & rank_bb(s);
+inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
+  Bitboard b = blockers & RMask[s];
+  return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
 }
 
-inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
-  return file_attacks_bb(s, blockers) | rank_attacks_bb(s, blockers);
+inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
+  Bitboard b = blockers & BMask[s];
+  return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
 }
 
-#elif defined(USE_32BIT_ATTACKS)
+#else // if !defined(IS_64BIT)
 
 inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
   Bitboard b = blockers & RMask[s];
@@ -335,17 +312,6 @@ inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
                    >> RShift[s])];
 }
 
-#else
-
-inline Bitboard rook_attacks_bb(Square s, Bitboard blockers) {
-  Bitboard b = blockers & RMask[s];
-  return RAttacks[RAttackIndex[s] + ((b * RMult[s]) >> RShift[s])];
-}
-
-#endif
-
-#if defined(USE_32BIT_ATTACKS)
-
 inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
   Bitboard b = blockers & BMask[s];
   return BAttacks[BAttackIndex[s] +
@@ -354,14 +320,7 @@ inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
                    >> BShift[s])];
 }
 
-#else // defined(USE_32BIT_ATTACKS)
-
-inline Bitboard bishop_attacks_bb(Square s, Bitboard blockers) {
-  Bitboard b = blockers & BMask[s];
-  return BAttacks[BAttackIndex[s] + ((b * BMult[s]) >> BShift[s])];
-}
-
-#endif // defined(USE_32BIT_ATTACKS)
+#endif
 
 inline Bitboard queen_attacks_bb(Square s, Bitboard blockers) {
   return rook_attacks_bb(s, blockers) | bishop_attacks_bb(s, blockers);
@@ -423,13 +382,31 @@ inline Bitboard isolated_pawn_mask(Square s) {
 }
 
 
+/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
+
+#if defined(IS_64BIT)
+
+inline Square first_1(Bitboard b) {
+  return Square(BitTable[((b & -b) * 0x218a392cd3d5dbfULL) >> 58]);
+}
+
+#else
+
+inline Square first_1(Bitboard b) {
+  b ^= (b - 1);
+  uint32_t fold = int(b) ^ int(b >> 32);
+  return Square(BitTable[(fold * 0x783a9b23) >> 26]);
+}
+
+#endif
+
+
 ////
 //// Prototypes
 ////
 
 extern void print_bitboard(Bitboard b);
 extern void init_bitboards();
-extern Square first_1(Bitboard b);
 extern Square pop_1st_bit(Bitboard *b);