Author: Tom Kerrigan
Date: 10:39:20 06/13/00
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On June 13, 2000 at 12:18:34, TEERAPONG TOVIRAT wrote: >Hi, > >I have 3 questions. >1. Does two level transpositional table have significant >advantages over one level table ? If so,how much we >gain in % ? > >2.In board representation,besides bitboard ,which is faster >between board 12x10(or 12x12) and board 0x88 ? >To generate the move,after obtaining piece and location, >the former takes one array look up and one arithmetic >operation to get a valid square.On the other hand,the >latter takes 2 times table look up(map and unmap) >and one arithmetic and one bitwise operation(&0x88) . >I think the former is better. Am I right ? I think this is the code that you're talking about. First, for the 10x12 board: n = a[b[n] + c]; // 1 add, 2 table lookups if (n == -1) // 1 subtract break; // 1 branch And here's the 0x88 code: n += c; // 1 add if (n & 0x88) // 1 logic break; // 1 branch So they're identical, except for the table lookups. The table lookups are what kill you though. With today's processors, addition and logic operations are basically instantaneous. So the 0x88 approach is much better. -Tom
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