Author: Gerd Isenberg
Date: 23:31:57 12/05/05
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On December 05, 2005 at 17:23:16, Alessandro Damiani wrote: >Just wondering: does anyone use flood-fill to detect open files? > >Alessandro I do it indirectly, i have front-span and back-span of both white and black pawns. Oring all spans and the pawns itself gets a set of all pawn occupied files - and the complement is the open-file set. Direct calculation is like that: bb = allPawns; bb |= bb >> 8; bb |= bb >> 16; bb |= bb >> 32; bb = ~bb & 0xff; // if you only need a file-set, take it here bb |= bb << 8; bb |= bb << 16; bb |= bb << 32; openFileSet = bb; Gerd
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