Use a flag in TT to track null search values

[stockfish] / src / value.h

diff --git a/src/value.h b/src/value.h
index 6e030db48c0debef8037b2c6f46675c505da29d9..4b62027267847592c63ef4a50895dc5b292625e4 100644 (file)
--- a/src/value.h
+++ b/src/value.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2009 Marco Costalba
+  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, 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
@@ -33,11 +33,16 @@
 ////
 
 enum ValueType {
-  VALUE_TYPE_NONE = 0,
+  VALUE_TYPE_NONE =  0,
   VALUE_TYPE_UPPER = 1,  // Upper bound
   VALUE_TYPE_LOWER = 2,  // Lower bound
   VALUE_TYPE_EXACT = 3,  // Exact score
-  VALUE_TYPE_EVAL  = 4   // Evaluation cache
+  VALUE_TYPE_EVAL  = 4,  // Static evaluation value
+  VALUE_TYPE_NULL  = 8,  // Null search value
+
+  VALUE_TYPE_EV_UP = VALUE_TYPE_EVAL | VALUE_TYPE_UPPER,
+  VALUE_TYPE_EV_LO = VALUE_TYPE_EVAL | VALUE_TYPE_LOWER,
+  VALUE_TYPE_NS_LO = VALUE_TYPE_NULL | VALUE_TYPE_LOWER,
 };
 
 
@@ -46,10 +51,49 @@ enum Value {
   VALUE_KNOWN_WIN = 15000,
   VALUE_MATE = 30000,
   VALUE_INFINITE = 30001,
-  VALUE_NONE = 30002
+  VALUE_NONE = 30002,
+  VALUE_ENSURE_SIGNED = -1
 };
 
 
+/// Score enum keeps a midgame and an endgame value in a single
+/// integer (enum), first LSB 16 bits are used to store endgame
+/// value, while upper bits are used for midgame value.
+
+// Compiler is free to choose the enum type as long as can keep
+// its data, so ensure Score to be an integer type.
+enum Score { ENSURE_32_BITS_SIZE_P = (1 << 16), ENSURE_32_BITS_SIZE_N = -(1 << 16)};
+
+// Extracting the _signed_ lower and upper 16 bits it not so trivial
+// because according to the standard a simple cast to short is
+// implementation defined and so is a right shift of a signed integer.
+inline Value mg_value(Score s) { return Value(((int(s) + 32768) & ~0xffff) / 0x10000); }
+
+// Unfortunatly on Intel 64 bit we have a small speed regression, so use a faster code in
+// this case, although not 100% standard compliant it seems to work for Intel and MSVC.
+#if defined(IS_64BIT) && (!defined(__GNUC__) || defined(__INTEL_COMPILER))
+inline Value eg_value(Score s) { return Value(int16_t(s & 0xffff)); }
+#else
+inline Value eg_value(Score s) { return Value((int)(unsigned(s) & 0x7fffu) - (int)(unsigned(s) & 0x8000u)); }
+#endif
+
+inline Score make_score(int mg, int eg) { return Score((mg << 16) + eg); }
+
+inline Score operator-(Score s) { return Score(-int(s)); }
+inline Score operator+(Score s1, Score s2) { return Score(int(s1) + int(s2)); }
+inline Score operator-(Score s1, Score s2) { return Score(int(s1) - int(s2)); }
+inline void operator+=(Score& s1, Score s2) { s1 = Score(int(s1) + int(s2)); }
+inline void operator-=(Score& s1, Score s2) { s1 = Score(int(s1) - int(s2)); }
+inline Score operator*(int i, Score s) { return Score(i * int(s)); }
+
+// Division must be handled separately for each term
+inline Score operator/(Score s, int i) { return make_score(mg_value(s) / i, eg_value(s) / i); }
+
+// Only declared but not defined. We don't want to multiply two scores due to
+// a very high risk of overflow. So user should explicitly convert to integer.
+inline Score operator*(Score s1, Score s2);
+
+
 ////
 //// Constants and variables
 ////
@@ -95,8 +139,7 @@ const Value PieceValueEndgame[17] = {
 
 /// Bonus for having the side to move (modified by Joona Kiiski)
 
-const Value TempoValueMidgame = Value(46);
-const Value TempoValueEndgame = Value(28);
+const Score TempoValue = make_score(48, 22);
 
 
 ////