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slider_moves.go
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slider_moves.go
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package chessEngine
import (
"math/bits"
)
type MagicPackage struct {
MagicNumber uint64
Shift uint8
MaximalBlockerMask Bitboard
}
var RookMagicPackages [64]MagicPackage
var BishopMagicPackages [64]MagicPackage
func OccupyRookMagicNumbers() {
randomNumberGenerator := RandomNumberGenerator{}
for square := uint8(0); square < 64; square++ {
magicPackage := &RookMagicPackages[square]
magicPackage.MaximalBlockerMask = GetRookBlockerMask(square)
numOfBlockerMaskBits := magicPackage.MaximalBlockerMask.CountSetBits()
magicPackage.Shift = uint8(64 - numOfBlockerMaskBits)
blockerMasks := make([]Bitboard, 1<<numOfBlockerMaskBits)
blockerMask := EmptyBitBoard
blockerMaskNumber := 0
for ok := true; ok; ok = (blockerMask != 0) {
blockerMasks[blockerMaskNumber] = blockerMask
blockerMaskNumber++
blockerMask = (blockerMask - magicPackage.MaximalBlockerMask) & magicPackage.MaximalBlockerMask
}
randomNumberGenerator.Seed(RandomNumberGeneratorSeeds[Rank(square)])
correctMagicNumberNotFound := true
for correctMagicNumberNotFound {
magicNumberAttempt := randomNumberGenerator.SparseRandom64()
magicPackage.MagicNumber = magicNumberAttempt
correctMagicNumberNotFound = false
ComputedRookMoves[square] = [4096]Bitboard{}
for blockerMaskNumber = 0; blockerMaskNumber < (1 << numOfBlockerMaskBits); blockerMaskNumber++ {
hashIndex := (uint64(blockerMasks[blockerMaskNumber]) * magicNumberAttempt) >> magicPackage.Shift
moveBitboard := getRookMoveBitboard(square, blockerMasks[blockerMaskNumber])
if ComputedRookMoves[square][hashIndex] != EmptyBitBoard && ComputedRookMoves[square][hashIndex] != moveBitboard {
correctMagicNumberNotFound = true
break
}
ComputedRookMoves[square][hashIndex] = moveBitboard
}
}
}
}
func OccupyBishopMagicNumbers() {
randomNumberGenerator := RandomNumberGenerator{}
for square := uint8(0); square < 64; square++ {
magicPackage := &BishopMagicPackages[square]
magicPackage.MaximalBlockerMask = getBishopBlockerMask(square)
numOfBlockerMaskBits := magicPackage.MaximalBlockerMask.CountSetBits()
magicPackage.Shift = uint8(64 - numOfBlockerMaskBits)
blockerMasks := make([]Bitboard, 1<<numOfBlockerMaskBits)
blockerMask := EmptyBitBoard
blockerMaskNumber := 0
for ok := true; ok; ok = (blockerMask != 0) {
blockerMasks[blockerMaskNumber] = blockerMask
blockerMaskNumber++
blockerMask = (blockerMask - magicPackage.MaximalBlockerMask) & magicPackage.MaximalBlockerMask
}
randomNumberGenerator.Seed(RandomNumberGeneratorSeeds[Rank(square)])
correctMagicNumberNotFound := true
for correctMagicNumberNotFound {
magicNumberAttempt := randomNumberGenerator.SparseRandom64()
magicPackage.MagicNumber = magicNumberAttempt
correctMagicNumberNotFound = false
ComputedBishopMoves[square] = [512]Bitboard{}
for blockerMaskNumber = 0; blockerMaskNumber < (1 << numOfBlockerMaskBits); blockerMaskNumber++ {
hashIndex := (uint64(blockerMasks[blockerMaskNumber]) * magicNumberAttempt) >> magicPackage.Shift
moveBitboard := getBishopMoveBitboard(square, blockerMasks[blockerMaskNumber])
if ComputedBishopMoves[square][hashIndex] != EmptyBitBoard && ComputedBishopMoves[square][hashIndex] != moveBitboard {
correctMagicNumberNotFound = true
break
}
ComputedBishopMoves[square][hashIndex] = moveBitboard
}
}
}
}
func GetRookBlockerMask(square uint8) Bitboard {
mask := EmptyBitBoard
mask |= SetFileMasks[File(square)]
mask &= ClearRankMasks[Rank1]
mask &= ClearRankMasks[Rank8]
mask |= SetRankMasks[Rank(square)]
if square%8 == 0 {
mask.ClearBit(uint8(0))
mask.ClearBit(uint8(square + 7))
mask.ClearBit(uint8(56))
} else if (square+1)%8 == 0 {
mask.ClearBit(uint8(7))
mask.ClearBit(uint8(square - 7))
mask.ClearBit(uint8(63))
} else {
mask &= ClearFileMasks[FileA]
mask &= ClearFileMasks[FileH]
}
mask.ClearBit(square)
return mask
}
func getBishopBlockerMask(square uint8) Bitboard {
mask := EmptyBitBoard
mask |= MainDiagonalMasks[File(square)-Rank(square)+7]
mask |= AntiDiagonalMasks[14-(Rank(square)+File(square))]
mask &= ClearRankMasks[Rank1]
mask &= ClearRankMasks[Rank8]
mask &= ClearFileMasks[FileA]
mask &= ClearFileMasks[FileH]
mask.ClearBit(square)
return mask
}
func getRookMoveBitboard(square uint8, occupancy Bitboard) Bitboard {
piece := uint64(BitboardForSquare[square])
occupied := uint64(occupancy)
rankMask := uint64(SetRankMasks[Rank(square)])
fileMask := uint64(SetFileMasks[File(square)])
westMoves := (occupied & rankMask) - 2*piece
eastMoves := bits.Reverse64(bits.Reverse64(occupied&rankMask) - 2*bits.Reverse64(piece))
westEastMoves := (westMoves ^ eastMoves) & rankMask
northMoves := (occupied & fileMask) - 2*piece
southMoves := bits.Reverse64(bits.Reverse64(occupied&fileMask) - 2*bits.Reverse64(piece))
northSouthMoves := (northMoves ^ southMoves) & fileMask
return Bitboard(westEastMoves | northSouthMoves)
}
func getBishopMoveBitboard(square uint8, occupancy Bitboard) Bitboard {
piece := uint64(BitboardForSquare[square])
occupied := uint64(occupancy)
mainDiagonalMask := uint64(MainDiagonalMasks[File(square)-Rank(square)+7])
antiDiagonalMask := uint64(AntiDiagonalMasks[14-(Rank(square)+File(square))])
southWestMoves := (occupied & mainDiagonalMask) - 2*piece
NorthEastMoves := bits.Reverse64(bits.Reverse64(occupied&mainDiagonalMask) - 2*bits.Reverse64(piece))
mainDiagonalMoves := (southWestMoves ^ NorthEastMoves) & mainDiagonalMask
southEastMoves := (occupied & antiDiagonalMask) - 2*piece
northWestMoves := bits.Reverse64(bits.Reverse64(occupied&antiDiagonalMask) - 2*bits.Reverse64(piece))
antiDiagonalMoves := (southEastMoves ^ northWestMoves) & antiDiagonalMask
return Bitboard(mainDiagonalMoves | antiDiagonalMoves)
}