Author: Gerd Isenberg
Date: 11:12:03 08/17/02
Go up one level in this thread
Hi Vincent,
actually it's faster on my AthlonXP with USE_LOOKUP_XYZ defined!?
Strange, i also would bet that the one without lookup is faster,
which only needs 4 instructions by your definition. I don't understand this
CISC-processors.
Tested in wrong bishop endings and KBN-K (without ETBs), where these inlines are
used quite often in eval and recognizers. In KBN-K 660KNodes versus 656KNodes.
But i don't played with optimizations so far (MSC++ minimize size optimization).
May be it's because m_sUDR[a][b] is accessed frequently with quite equal "a" or
"b" and therefore is mostly already in first level cache - or a lack of
registers. But the code is definitely shorter with lookup.
#ifdef USE_LOOKUP_XYZ
inline BOOL sameSquareColor(int a, int b) {return (m_sUDR[a][b]^1) & 1;}
inline BOOL oppoSquareColor(int a, int b) {return m_sUDR[a][b] & 1;}
#else
inline BOOL sameSquareColor(int a, int b) {return (((a^b)>>3)^(a^b)^1) & 1;}
inline BOOL oppoSquareColor(int a, int b) {return (((a^b)>>3)^(a^b)) & 1;}
#endif
(((a^b)>>3)^(a^b)) & 1;
2 xors because only one (a^b) is necessary
1 shift
1 and
------
4 instructions
see you,
Gerd
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