X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=dd8023e9bd5770eef292f87301750dc55b1ccbcf;hp=04b46e5d3603f8275ad3643c4385ceab0d286074;hb=b833c8247afcfd4a5404b0473f31ebddb23f57d6;hpb=d1d44376994e356e0bc79ebb69607ef395ffa6e0

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 04b46e5d..dd8023e9 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -297,8 +297,8 @@ void init_bitboards() {
 
 #if defined(IS_64BIT) && !defined(USE_BSFQ)
 
-CACHE_LINE_ALIGNMENT
-static const int BitTable[64] = {
+static CACHE_LINE_ALIGNMENT
+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,
@@ -317,8 +317,8 @@ Square pop_1st_bit(Bitboard* b) {
 
 #elif !defined(USE_BSFQ)
 
-CACHE_LINE_ALIGNMENT
-static const int BitTable[64] = {
+static CACHE_LINE_ALIGNMENT
+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,
@@ -336,30 +336,72 @@ union b_union {
 
     Bitboard b;
     struct {
+#if defined (BIGENDIAN)
+        uint32_t h;
+        uint32_t l;
+#else
         uint32_t l;
         uint32_t h;
+#endif
     } dw;
 };
 
-// WARNING: Needs -fno-strict-aliasing compiler option
 Square pop_1st_bit(Bitboard* bb) {
 
-  b_union u;
+   b_union u;
+   Square ret;
+
+   u.b = *bb;
+
+   if (u.dw.l)
+   {
+       ret = Square(BitTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783a9b23) >> 26]);
+       u.dw.l &= (u.dw.l - 1);
+       *bb = u.b;
+       return ret;
+   }
+   ret = Square(BitTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783a9b23) >> 26]);
+   u.dw.h &= (u.dw.h - 1);
+   *bb = u.b;
+   return ret;
+}
 
-  u.b = *bb;
+#endif
 
-  if (u.dw.l)
-  {
-      *((uint32_t*)bb) = u.dw.l & (u.dw.l - 1);
-      return Square(BitTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783a9b23) >> 26]);
-  }
+// Optimized bitScanReverse32() implementation by Pascal Georges. Note
+// that first bit is 1, this allow to differentiate between 0 and 1.
+static CACHE_LINE_ALIGNMENT
+const char MsbTable[256] = {
+  0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5,
+  5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+  8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+  8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+  8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+  8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+  8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8
+};
 
-  *((uint32_t*)bb+1) = u.dw.h & (u.dw.h - 1); // Little endian only?
-  return Square(BitTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783a9b23) >> 26]);
+int bitScanReverse32(uint32_t b)
+{
+   int result = 0;
+
+   if (b > 0xFFFF)
+   {
+      b >>= 16;
+      result += 16;
+   }
+   if (b > 0xFF)
+   {
+      b >>= 8;
+      result += 8;
+   }
+   return result + MsbTable[b];
 }
 
-#endif
-
 namespace {
 
   // All functions below are used to precompute various bitboards during