X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=b19d401af19ad6e13bf36071cdba05cbca9bca5f;hp=ccde19057c0893106789f10df6c659dc9f629401;hb=2af2c67650c4ac2531e6ab2753830f91c0999876;hpb=822695d4d3a9336dc54bfabd0996e75865358ae2

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index ccde1905..b19d401a 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -45,27 +45,11 @@ Magic BishopMagics[SQUARE_NB];
 
 namespace {
 
-  // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
-  const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL;
-  const uint32_t DeBruijn32 = 0x783A9B23;
-
-  int MSBTable[256];            // To implement software msb()
-  Square BSFTable[SQUARE_NB];   // To implement software bitscan
   Bitboard RookTable[0x19000];  // To store rook attacks
   Bitboard BishopTable[0x1480]; // To store bishop attacks
 
   void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
 
-  // bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses
-  // Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch.
-
-  unsigned bsf_index(Bitboard b) {
-    b ^= b - 1;
-    return Is64Bit ? (b * DeBruijn64) >> 58
-                   : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26;
-  }
-
-
   // popcount16() counts the non-zero bits using SWAR-Popcount algorithm
 
   unsigned popcount16(unsigned u) {
@@ -76,46 +60,6 @@ namespace {
   }
 }
 
-#ifdef NO_BSF
-
-/// Software fall-back of lsb() and msb() for CPU lacking hardware support
-
-Square lsb(Bitboard b) {
-  assert(b);
-  return BSFTable[bsf_index(b)];
-}
-
-Square msb(Bitboard b) {
-
-  assert(b);
-  unsigned b32;
-  int result = 0;
-
-  if (b > 0xFFFFFFFF)
-  {
-      b >>= 32;
-      result = 32;
-  }
-
-  b32 = unsigned(b);
-
-  if (b32 > 0xFFFF)
-  {
-      b32 >>= 16;
-      result += 16;
-  }
-
-  if (b32 > 0xFF)
-  {
-      b32 >>= 8;
-      result += 8;
-  }
-
-  return Square(result + MSBTable[b32]);
-}
-
-#endif // ifdef NO_BSF
-
 
 /// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
 /// to be printed to standard output. Useful for debugging.
@@ -145,13 +89,7 @@ void Bitboards::init() {
       PopCnt16[i] = (uint8_t) popcount16(i);
 
   for (Square s = SQ_A1; s <= SQ_H8; ++s)
-  {
-      SquareBB[s] = 1ULL << s;
-      BSFTable[bsf_index(SquareBB[s])] = s;
-  }
-
-  for (Bitboard b = 2; b < 256; ++b)
-      MSBTable[b] = MSBTable[b - 1] + !more_than_one(b);
+      SquareBB[s] = make_bitboard(s);
 
   for (File f = FILE_A; f <= FILE_H; ++f)
       FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;