Using Bitboards for Move Generation in Shogi

In this paper it will be explained how to use bitboards for move generation in shogi. In chess, bitboards have been used in most strong programs because of the easy representation of a chess board by a single 64-bit integer. For shogi, a less efficient representation has to be used because a shogi board has 81 squares instead of 64. A representation with an array of three integers is proposed, where each integer represents 27 squares of the board. This representation is then used for move generation in a similar way to the methods used in chess, for example by using rotated bitboards for generating the moves of the sliding pieces rook, bishop and lance. A comparison of move generation speed between the method using bitboards and by using the more common method of attack tables showed that by using bitboards the move generation speed of the program Spear was improved by 48.8%.

• Type: Journal
• Year: 2007
• Where: ICGA
• Authors: Reijer Grimbergen
• Keywords: Generation, ICGA 1997, ICGA 2007, Shogi, Single 64-bit Integer