Author: Gerd Isenberg
Date: 12:52:39 04/14/04
Hi Rasjid,
i found a slight improvement in one of your three interesting sliding attack
macros. It replaces the "inbetween"-expression
isqBit(y)-1 & ~( isqBit(x)-1 | isqBit(x) )
by
isqBit(y) - isqBit(x+1)
or
isqBit(y) -(isqBit(x)<<1)
If one subtracts power of two values, greater minus less:
0100 0000
-0000 0100 the result is
=0011 1100 a "inner" sequence of ones, except "less" is included.
So we start with next greater bit of "less".
Couldn't resist to use inlines instead of macros ;-)
(not tested!)
Cheers,
Gerd
typedef unsigned _int64 U64
#define GetFile64(sq) ((sq) & 7)
#define GetRank64(sq) ((sq) >> 3)
#define iGetFile(sq88) ((sq88) & 7)
#define iGetRank(sq88) ((sq88) >> 4)
#define sq88Bit(sq88) ((U64)1 << (((sq88) + ((sq88) & 7)) >> 1))
#define sq64Bit(sq64) (((U64)1) << (sq64))
#define sq88RankBits(sq88) ((U64)0xff << ((sq88) >> 1 & 0370))
#define sq88FileBits(sq88) ((U64) 0x0101010101010101 << ((sq88) & 7))
//*** global variables
U64 all, diagonal[2][15];
inline // __forceinline
bool brq_path_clear(int x, int y, U64 path) {
if (x < y) return ((isqBit(y) - isqBit(x+1)) & path & all) == 0;
if (x > y) return ((isqBit(x) - isqBit(y+1)) & path & all) == 0;
return false;
}
inline // __forceinline
bool bstyle_attack(int x, int y) {
if ( iGetRank(x) + iGetFile(x) == iGetRank(y) + iGetFile(y) )
return brq_path_clear(x, y, diagonal[1][iGetRank(x) + iGetFile(x)]);
if ( iGetRank(x) - iGetFile(x) == iGetRank(y) - iGetFile(y) )
return brq_path_clear(x, y, diagonal[0][7 + iGetRank(x) - iGetFile(x)]);
return false;
}
inline // __forceinline
bool rstyle_attack(int x, int y) {
if ( iGetRank(x) == iGetRank(y) )
return brq_path_clear(x, y, isqRankBits(x));
if ( iGetFile(x) == iGetFile(y) )
return brq_path_clear(x, y, isqFileBits(x));
return false;
}
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