Author: Robert Hyatt
Date: 21:51:27 06/07/02
Go up one level in this thread
On June 07, 2002 at 14:05:04, Robert Henry Durrett wrote: >On June 07, 2002 at 13:59:22, Dann Corbit wrote: > >>On June 07, 2002 at 12:02:39, Robert Henry Durrett wrote: >> >>>When 16-bit seemed like the only possible future, people didn't write their >>>programs for ease of modification to 32-bit. >>> >>>Now that 64-bit is on the horizon, the 32-bit guys are starting to worry. >>> >>>The trend is there. There will be 128, 256, and who knows how big? >>> >>>It's a good idea to write programs so that the future mods will not be so >>>painful. >>> >>>Unfortunately, that may be easier said than done. >>> >>>Along with the increases in wordlength, there likely will be other changes not >>>so easy to forsee. >>> >>>Perhaps the new 64-bit processors are actually not just using longer word >>>lengths but also are different in other ways. >>> >>>Maybe it's not so easy to prepare after all. >> >>64 bit chips are a natural fit for chess programs. There are 64 squares on a >>chess board and 64 bits in a 64 bit integer. I don't think (except for better >>bandwidth) that 128 bits will do much for chess programs. > >Maybe someone will find a way to use the two bits per square? Can have more >information in two bits than in one. > >Just my "two bits worth." [Pardon the pun?] > >Bob D. One natural idea: 00 = empty square, 01 = white piece, 10=black piece. Now the "occupied square" bitboard can be ANDed with a mask containing nothing but 01010101 to find just the white pieces, or just 1010101010 for just white pieces, etc. As with the current 64-bit bitmaps, it will take some time and thought to come up with creative ways to use 128. In Crafty, for example, I might combine two of the rotated bitmaps into one 128 bit entry and update _both_ with one boolean operation (XOR)... Or I might expand a square to 2 (or 4 bits when we see 256 bit processors). 256 would be particularly nice since there are only 13 possible states for a square, 6 white pieces, 6 black pieces, or empty. That has interesting possibilities too... Now we might play around with the traditional "mailbox" approach but apply bitmap techniques to it since we can operate on the entire 64 square board with one instruction. Who knows what might come of that...
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.