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62 lines
1.3 KiB
62 lines
1.3 KiB
4 years ago
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package chess
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import (
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"strconv"
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"strings"
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)
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// bitboard is a board representation encoded in an unsigned 64-bit integer. The
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// 64 board positions begin with A1 as the most significant bit and H8 as the least.
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type bitboard uint64
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func newBitboard(m map[Square]bool) bitboard {
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s := ""
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for sq := 0; sq < numOfSquaresInBoard; sq++ {
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if m[Square(sq)] {
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s += "1"
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} else {
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s += "0"
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}
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}
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bb, err := strconv.ParseUint(s, 2, 64)
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if err != nil {
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panic(err)
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}
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return bitboard(bb)
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}
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func (b bitboard) Mapping() map[Square]bool {
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m := map[Square]bool{}
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for sq := 0; sq < numOfSquaresInBoard; sq++ {
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if b&bbForSquare(Square(sq)) > 0 {
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m[Square(sq)] = true
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}
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}
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return m
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}
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// String returns a 64 character string of 1s and 0s starting with the most significant bit.
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func (b bitboard) String() string {
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s := strconv.FormatUint(uint64(b), 2)
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return strings.Repeat("0", numOfSquaresInBoard-len(s)) + s
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}
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// Draw returns visual representation of the bitboard useful for debugging.
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func (b bitboard) Draw() string {
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s := "\n A B C D E F G H\n"
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for r := 7; r >= 0; r-- {
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s += Rank(r).String()
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for f := 0; f < numOfSquaresInRow; f++ {
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sq := getSquare(File(f), Rank(r))
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if b.Occupied(sq) {
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s += "1"
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} else {
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s += "0"
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}
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s += " "
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}
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s += "\n"
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}
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return s
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}
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