Retire bitScanReverse32()

Use log() instead because we are not in speed
critical paths.

Also a bit of renaming and code shuffle while there.

No functional change.

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

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index f014fe1939b6d4da4b13c5eafe1d286b8ae3312a..063204c5020f7ec2f54a5104ee705a618068fc4b 100644 (file)
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -373,39 +373,6 @@ Square pop_1st_bit(Bitboard* bb) {
 
 #endif
 
 
 #endif
 

-// 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
-};
-
-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];
-}

 
 namespace {
 
 
 namespace {
 

diff --git a/src/bitboard.h b/src/bitboard.h
index 1ad5fdcb305b8a09ce2ac9cb37020c1d3a5dd784..9d0611867a4990ecf4f5e37ec48d39c4f8ef14b5 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -342,7 +342,6 @@ extern Square pop_1st_bit(Bitboard* b);
 
 extern void print_bitboard(Bitboard b);
 extern void init_bitboards();
 
 extern void print_bitboard(Bitboard b);
 extern void init_bitboards();

-extern int bitScanReverse32(uint32_t b);

 
 
 #endif // !defined(BITBOARD_H_INCLUDED)
 
 
 #endif // !defined(BITBOARD_H_INCLUDED)

diff --git a/src/search.cpp b/src/search.cpp
index f11388c595a162a1d77ddddb046d192bfd01945e..30179e8f27fafa2c931c3ef0840d95875a21b568 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -337,6 +337,51 @@ void exit_threads() { TM.exit_threads(); }
 int64_t nodes_searched() { return TM.nodes_searched(); }
 
 
 int64_t nodes_searched() { return TM.nodes_searched(); }
 
 

+/// init_search() is called during startup. It initializes various lookup tables
+
+void init_search() {
+
+  int d;  // depth (OnePly == 2)
+  int hd; // half depth (OnePly == 1)
+  int mc; // moveCount
+
+  // Init reductions array
+  for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++)
+  {
+      double    pvRed = log(double(hd)) * log(double(mc)) / 3.0;
+      double nonPVRed = log(double(hd)) * log(double(mc)) / 1.5;
+      ReductionMatrix[PV][hd][mc]    = (int8_t) (   pvRed >= 1.0 ? floor(   pvRed * int(OnePly)) : 0);
+      ReductionMatrix[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
+  }
+
+  // Init futility margins array
+  for (d = 0; d < 16; d++) for (mc = 0; mc < 64; mc++)
+      FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1) - 8 * mc + 45;
+
+  // Init futility move count array
+  for (d = 0; d < 32; d++)
+      FutilityMoveCountArray[d] = 3 + (1 << (3 * d / 8));
+}
+
+
+// SearchStack::init() initializes a search stack. Used at the beginning of a
+// new search from the root.
+void SearchStack::init(int ply) {
+
+  pv[ply] = pv[ply + 1] = MOVE_NONE;
+  currentMove = threatMove = MOVE_NONE;
+  reduction = Depth(0);
+  eval = VALUE_NONE;
+}
+
+void SearchStack::initKillers() {
+
+  mateKiller = MOVE_NONE;
+  for (int i = 0; i < KILLER_MAX; i++)
+      killers[i] = MOVE_NONE;
+}
+
+

 /// perft() is our utility to verify move generation is bug free. All the legal
 /// moves up to given depth are generated and counted and the sum returned.
 
 /// perft() is our utility to verify move generation is bug free. All the legal
 /// moves up to given depth are generated and counted and the sum returned.
 


@@ -549,51 +594,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
 }
 
 
 }
 
 

-/// init_search() is called during startup. It initializes various lookup tables
-
-void init_search() {
-
-  // Init our reduction lookup tables
-  for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
-      for (int j = 1; j < 64; j++) // j == moveNumber
-      {
-          double    pvRed = log(double(i)) * log(double(j)) / 3.0;
-          double nonPVRed = log(double(i)) * log(double(j)) / 1.5;
-          ReductionMatrix[PV][i][j]    = (int8_t) (   pvRed >= 1.0 ? floor(   pvRed * int(OnePly)) : 0);
-          ReductionMatrix[NonPV][i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
-      }
-
-  // Init futility margins array
-  for (int i = 0; i < 16; i++) // i == depth (OnePly = 2)
-      for (int j = 0; j < 64; j++) // j == moveNumber
-      {
-          // FIXME: test using log instead of BSR
-          FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j + 45;
-      }
-
-  // Init futility move count array
-  for (int i = 0; i < 32; i++) // i == depth (OnePly = 2)
-      FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8));
-}
-
-
-// SearchStack::init() initializes a search stack. Used at the beginning of a
-// new search from the root.
-void SearchStack::init(int ply) {
-
-  pv[ply] = pv[ply + 1] = MOVE_NONE;
-  currentMove = threatMove = MOVE_NONE;
-  reduction = Depth(0);
-  eval = VALUE_NONE;
-}
-
-void SearchStack::initKillers() {
-
-  mateKiller = MOVE_NONE;
-  for (int i = 0; i < KILLER_MAX; i++)
-      killers[i] = MOVE_NONE;
-}
-

 namespace {
 
   // id_loop() is the main iterative deepening loop. It calls root_search
 namespace {
 
   // id_loop() is the main iterative deepening loop. It calls root_search