/*
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
////
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_EV_UP = 5, // Evaluation cache for upper bound
- VALUE_TYPE_EV_LO = 6 // Evaluation cache for lower bound
+ 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
};
VALUE_KNOWN_WIN = 15000,
VALUE_MATE = 30000,
VALUE_INFINITE = 30001,
- VALUE_NONE = 30002
+ VALUE_NONE = 30002,
+ VALUE_ENSURE_SIGNED = -1
};
-/// Score struct keeps a midgame and an endgame value in a single
-/// ScoreValue 64 bit union.
+/// 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.
-union ScoreValue {
- int64_t v64;
- struct {
- int32_t mgv;
- int32_t egv;
- } v32;
-};
+// 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)};
-struct Score {
+// 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); }
- Score() {}
- Score(const Score& s) { v = s.v; }
- Score(int mg, int eg) { v.v32.mgv = int32_t(mg); v.v32.egv = int32_t(eg); }
+// 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
- Score& operator=(const Score& s) { v = s.v; return *this; }
- Score& operator+=(const Score& s) { v.v32.mgv += s.v.v32.mgv; v.v32.egv += s.v.v32.egv; return *this; }
- Score& operator-=(const Score& s) { v.v32.mgv -= s.v.v32.mgv; v.v32.egv -= s.v.v32.egv; return *this; }
+inline Score make_score(int mg, int eg) { return Score((mg << 16) + eg); }
- Value mg() const { return Value(v.v32.mgv); }
- Value eg() const { return Value(v.v32.egv); }
+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)); }
-private:
- ScoreValue v;
-};
+// 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); }
-inline Score operator*(int i, Score s) { return Score(i * s.mg(), i * s.eg()); }
-inline Score operator*(Score s, int i) { return s * i; }
-inline Score operator-(Score s) { return Score(-s.mg(), -s.eg()); }
+// 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);
-extern std::ostream& operator<<(std::ostream& os, Score s);
////
//// Constants and variables
/// Bonus for having the side to move (modified by Joona Kiiski)
-const Score TempoValue = Score(48, 22);
+const Score TempoValue = make_score(48, 22);
////