X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fvalue.h;h=364844555abead4ca5b79d62a819f024c6cad5a8;hp=4f19cdaa554b64f29a2d9c820dd1e2c77012f632;hb=a1b8c8109b464abd9d026b1ef740f1bace814b29;hpb=12aeac5e148ff842ed80a62db6c7a6c6c99a92ed

diff --git a/src/value.h b/src/value.h
index 4f19cdaa..36484455 100644
--- 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); }