Author: Uri Blass
Date: 02:53:17 10/16/03
Go up one level in this thread
On October 16, 2003 at 05:07:43, Gerd Isenberg wrote: >On October 16, 2003 at 03:16:58, Axel Schumacher wrote: > >>Hi, >>I stumbled across the new engine Gothic Vortex, which seems to be a 80 bit >>engine! What is your opinion to this approach? > >Hi Axel, > >an interesting chess vaiant with 10*8 board and two new pieces, the "Chancellor" >combines Knight and Rook, "Archbishop" Knight and Bishop. >I only know about the Archbishop in "Janusschach", also with 10*8 board, but >with two Archbishops per side between Rook and Knight in the initial position. > >Some statements in the paper are questionable: > ><snip> >>... However, not all computer operating systems perform native >>64-bit math manipulations. So, 64-bit program code is "emulated" by using pairs >>of 32-bit constructions. >> >>Such emulation slows down the overall performance by at least a factor of two. >>But what other choices does one have? > >Considering internal datapathes are already 64-bit or more in current 32-bit >cpu's and 32-bit instructions are shorter and may processed simultaniously, that >statement seems to be too optimistic. > >The problem with current 32-bit architectures like x86-32 is the lack of 32-bit >registers. > >> >>It is possible to use an Array Move Generator. Most programmers who attempt to >>write something as complex as a chess program first build an Array Move >>Generator. On the plus side, an Array Move Generator is easier to program and >>debug. It also "makes sense" to think in terms of an Array Move Generator, since >>the computer instructions used to encode the program closely resemble the >>process a human player might use to do the same thing. On the minus side, an >>Array Move Generator is many times slower than a Bitboard Move Generator. A >>recent experiment showed that the Bitboard Move Generator in the Gothic Vortex >>program is about 30 times as fast as the Array Move Generator found in the >>Zillions-Of-Games engine. > >Ok, i guess the "Array" Move Generator is simply a very "bad" implementation. >And as we all know Move Generation is at most a negligible part of a chess >engine. I think it is dependent on the engine(an engine may generate moves as part of its evaluation function and give a score for every move) Note that I do not understand how can you be 30 times slower with an array. I have arrays for king moves and for knight moves something like: kingmove[64][8] knightmove[64][8] numkingmoves[64] numknightmoves[64] It may be not the best way to generate moves and it is possible that something like 16 bit int array directionkingknight[64] and a loop on the directions may be faster but I do not think that it is so slow that it is possible to find the relevant squares and to check the color of the target square 30 times faster. Uri
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