Fix silly MSVC warning

[stockfish] / src / value.h

diff --git a/src/value.h b/src/value.h
index 03ae24b7832770fa19128c5dc8e609bd230ec2d9..364844555abead4ca5b79d62a819f024c6cad5a8 100644 (file)
--- a/src/value.h
+++ b/src/value.h
@@ -52,13 +52,26 @@ enum Value {
 };
 
 
-/// Score struct keeps a midgame and an endgame value in a single
-/// ScoreValue 64 bit union.
-
-enum Score;
-
+/// 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)); }
-inline Value mg_value(Score s) { return Value((int(s) + 32768) >> 16); }
+#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); }
 
@@ -68,20 +81,14 @@ 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)); }
-inline Score operator/(Score s, int i) { return Score(int(s) / i); }
+
+// 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);
 
-// Following are only declared to prevent erroneus instantations
-inline Score operator*(Score s, int i);
-inline Score operator/(Score s1, Score s2);
-inline Score operator+(Score s, int i);
-inline Score operator+(int i, Score s);
-inline Score operator-(Score s, int i);
-inline Score operator-(int i, Score s);
-
 
 ////
 //// Constants and variables