Restore correct 64 bit version of pop_1st_bit()

Was erroneusly changed with the 32bit in recent
patch "Retire USE_COMPACT_ROOK_ATTACKS...".

Also another clean up of define magics. Move compiler
specific definitions in types.h and remove redundant cruft.

Now this macro ugly mess seems more reasonable.

No functional change.

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

src/bitboard.cpp

@@ -242,20 +242,44 @@ void init_bitboards() {
 }
 
 
+/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
 /// nonzero bitboard.
 
 #if defined(IS_64BIT) && !defined(USE_BSFQ)
 
+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
+};
+
+Square first_1(Bitboard b) {
+  return Square(BitTable[((b & -b) * 0x218a392cd3d5dbfULL) >> 58]);
+}
+
 Square pop_1st_bit(Bitboard* b) {
-  Bitboard bb = *b ^ (*b - 1);
+  Bitboard bb = *b;
-  uint32_t fold = int(bb) ^ int(bb >> 32);
   *b &= (*b - 1);
-  return Square(BitTable[(fold * 0x783a9b23) >> 26]);
+  return Square(BitTable[((bb & -bb) * 0x218a392cd3d5dbfULL) >> 58]);
 }
 
 #elif !defined(USE_BSFQ)
 
+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
+};
+
+Square first_1(Bitboard b) {
+  b ^= (b - 1);
+  uint32_t fold = int(b) ^ int(b >> 32);
+  return Square(BitTable[(fold * 0x783a9b23) >> 26]);
+}
+
 // Use type-punning
 union b_union {
 

src/bitboard.h

@@ -22,25 +22,6 @@
 #if !defined(BITBOARD_H_INCLUDED)
 #define BITBOARD_H_INCLUDED
 
-////
-//// Defines
-////
-
-// Quiet a warning on Intel compiler
-#if !defined(__SIZEOF_INT__ )
-#define __SIZEOF_INT__ 0
-#endif
-
-// Check for 64 bits for different compilers: Intel, MSVC and gcc
-#if defined(__x86_64) || defined(_WIN64) || (__SIZEOF_INT__ > 4)
-#define IS_64BIT
-#endif
-
-#if defined(IS_64BIT) && (defined(__GNUC__) || defined(__INTEL_COMPILER))
-#define USE_BSFQ
-#endif
-
-
 ////
 //// Includes
 ////
@@ -51,13 +32,6 @@
 #include "types.h"
 
 
-////
-//// Types
-////
-
-typedef uint64_t Bitboard;
-
-
 ////
 //// Constants and variables
 ////
@@ -132,13 +106,6 @@ 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];
 
@@ -407,12 +374,7 @@ inline Square __attribute__((always_inline)) pop_1st_bit(Bitboard* b) {
 
 #else // if !defined(USE_BSFQ)
 
-inline Square first_1(Bitboard b) {
+extern Square first_1(Bitboard b);
-  b ^= (b - 1);
-  uint32_t fold = int(b) ^ int(b >> 32);
-  return Square(BitTable[(fold * 0x783a9b23) >> 26]);
-}
-
 extern Square pop_1st_bit(Bitboard* b);
 
 #endif

src/bitcount.h

@@ -28,29 +28,7 @@
 //#define DISABLE_POPCNT_SUPPORT
 
 
-#include "bitboard.h"
+#include "types.h"
-
-
-// Select type of software bit count function to use
-
-#if !defined(AUTO_CONFIGURATION) || defined(IS_64BIT)
-
-//#define USE_COMPACT_ROOK_ATTACKS
-//#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-
-#define BITCOUNT_SWAR_64
-//#define BITCOUNT_SWAR_32
-//#define BITCOUNT_LOOP
-
-#else
-
-#define USE_32BIT_ATTACKS
-#define USE_FOLDED_BITSCAN
-#define BITCOUNT_SWAR_32
-
-#endif
-
 
 // Select type of intrinsic bit count instruction to use
 
@@ -86,24 +64,29 @@ inline bool cpu_has_popcnt() { return false; }
 
 #define POPCNT_INTRINSIC(x) count_1s(x)
 
-#endif
+#endif // cpu_has_popcnt() selection
 
 
 /// Software implementation of bit count functions
 
-#if defined(BITCOUNT_LOOP)
+#if defined(IS_64BIT)
 
 inline int count_1s(Bitboard b) {
-  int r;
+  b -= ((b>>1) & 0x5555555555555555ULL);
-  for(r = 0; b; r++, b &= b - 1);
+  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
-  return r;
+  b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
+  b *= 0x0101010101010101ULL;
+  return int(b >> 56);
 }
 
 inline int count_1s_max_15(Bitboard b) {
-  return count_1s(b);
+  b -= (b>>1) & 0x5555555555555555ULL;
+  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
+  b *= 0x1111111111111111ULL;
+  return int(b >> 60);
 }
 
-#elif defined(BITCOUNT_SWAR_32)
+#else // if !defined(IS_64BIT)
 
 inline int count_1s(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
@@ -128,23 +111,6 @@ inline int count_1s_max_15(Bitboard b) {
   return int(v >> 28);
 }
 
-#elif defined(BITCOUNT_SWAR_64)
-
-inline int count_1s(Bitboard b) {
-  b -= ((b>>1) & 0x5555555555555555ULL);
-  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
-  b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
-  b *= 0x0101010101010101ULL;
-  return int(b >> 56);
-}
-
-inline int count_1s_max_15(Bitboard b) {
-  b -= (b>>1) & 0x5555555555555555ULL;
-  b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
-  b *= 0x1111111111111111ULL;
-  return int(b >> 60);
-}
-
 #endif // BITCOUNT
 
 
@@ -177,7 +143,7 @@ const bool CpuHasPOPCNT = cpu_has_popcnt();
 
 // Global variable used to print info about the use of 64 optimized
 // functions to verify that a 64bit compile has been correctly built.
-#if defined(BITCOUNT_SWAR_64)
+#if defined(IS_64BIT)
 const bool CpuHas64BitPath = true;
 #else
 const bool CpuHas64BitPath = false;

src/types.h

@@ -41,7 +41,29 @@ typedef __int64 int64_t;
 
 #endif // !defined(_MSC_VER)
 
-// Hash keys:
+// Hash keys
 typedef uint64_t Key;
 
+// Bitboard type
+typedef uint64_t Bitboard;
+
+
+////
+//// Compiler specific defines
+////
+
+// Quiet a warning on Intel compiler
+#if !defined(__SIZEOF_INT__ )
+#define __SIZEOF_INT__ 0
+#endif
+
+// Check for 64 bits for different compilers: Intel, MSVC and gcc
+#if defined(__x86_64) || defined(_WIN64) || (__SIZEOF_INT__ > 4)
+#define IS_64BIT
+#endif
+
+#if defined(IS_64BIT) && (defined(__GNUC__) || defined(__INTEL_COMPILER))
+#define USE_BSFQ
+#endif
+
 #endif // !defined(TYPES_H_INCLUDED)