Author: Peter Fendrich
Date: 12:27:10 08/19/98
continuing from Part1...
Method C (The Hacker trick without loops. Used by DarkThought)
..............................................
#define ONES ((uint64) 0x5555555555555555)
#define TWOS ((uint64) 0x3333333333333333)
#define FOURS ((unsigned __int32) 0x0f0f0f0f)
register unsigned __int32 n;
const uint64 a = TheBitBoard - ((TheBitBoard >> 1) & ONES);
const uint64 c = (a & TWOS) + ((a >> 2) & TWOS);
n = ((unsigned __int32) c) + ((unsigned __int32) (c >> 32));
n = (n & FOURS) + ((n >> 4) & FOURS);
n = (n & 0xFFFF) + (n >> 16);
n = (n & 0xFF) + (n >> 8);
return n;
..............................................
Pos Time Iter Mve# Nodes N/S
--- --- ---- ---- -------- -----
d1 111 10 1 3373271 30389
d2 179 9 13 5482500 30628
d3 92 8 2 1906069 20718
d4 93 8 3 2469504 26553
d5 92 9 6 3498022 38021
N1 97 8 30 3847980 39669
N2 92 9 6 2711814 29476
N3 116 9 1 3352784 28903
N4 91 8 13 3177590 34918
N5 103 9 1 4545646 44132
Total: 1066 87 34365180
Mean: 107 9 32238
Method D (Table lookup)
........................................
UINT register c;
c = table[TheBitBoard.row[0]];
c += table[TheBitBoard.row[1]];
c += table[TheBitBoard.row[2]];
c += table[TheBitBoard.row[3]];
c += table[TheBitBoard.row[4]];
c += table[TheBitBoard.row[5]];
c += table[TheBitBoard.row[6]];
c += table[TheBitBoard.row[7]];
return c;
.........................................
Pos Time Iter Mve# Nodes N/S
---- ---- ---- ---- -------- -----
d1 116 10 1 3373153 29078
d2 148 9 2 4530241 30609
d3 96 8 6 2097610 21850
d4 92 8 4 2508042 27261
d5 92 9 7 3393436 36885
N1 91 8 27 3457069 37989
N2 95 9 6 2647945 27873
N3 124 9 1 3359300 27091
N4 92 8 11 2965104 32229
N5 108 9 1 4456583 41264
Total: 1054 87 32788483
Mean: 105 9 31109
====================================================================
Conclusion:
Method A, "the Crafty" method works best for my program. This is confirmed by
other tests.
My program Terra uses the bitcounter very much in the Evaluation. Therefore it
has a big so impact on performance.
Comments?
I will continue with different getFirstBit, getLastBit, popFirstBit, popLastBit
etc...
//Peter
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