Author: Gerd Isenberg
Date: 06:42:31 01/06/04
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On January 06, 2004 at 08:12:57, Anthony Cozzie wrote: >On January 06, 2004 at 03:09:57, Matt Thomas wrote: > >>This question is for those who have designed and built their own chess engine. >>How long did it take you? > >It takes years. I started working on Zappa almost 3 years ago; it is still far >from competitive with crafty / yace, let alone the commercial programs. It also >depends on how much stuff you copy from Crafty/Gerbil/TSCP. > >>seemed to me that they would be handled with twice the amount of instruction >>cycles because there are only 32 bit registers and each 64 bit value would >>likely be broken into two 32 bit values for math operations. So the appearance >>of a single-pass 64 bit math operation really is handled as two 32 bit values >>would be handled. ...unless I am missing something. >> >>I ask because I had seen a 64 bit integer value being used in some code and >>thought it was not really giving a speed gain on 32 bit hardware. > >It isn't. Bitboards are slower than attack tables on 32 bit hardware. For >example, a 64 bit shift on 32 bit hardware is something like 10 instructions and >includes a conditional branch. On x86-32 64-bit shift are two instructions only, 7 bytes opcode: shld edx,ecx,9 shl ecx,9 shrd ecx,edx,7 shr edx,7 > I _think_ they are faster on 64 bit hardware, >but there aren't really enough data points. I have a dual opteron though, so >we'll be finding out soon :) > >anthony
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