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bitboard_utils.py
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bitboard_utils.py
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from numba import njit, void, uint64, int8, int16
from numba.types import UniTuple
import numpy as np
LEFT_MASK = 0x7F7F7F7F7F7F7F7F
RIGHT_MASK = 0xFEFEFEFEFEFEFEFE
@njit(int8(uint64), cache = True)
def count_bits(x):
# https://www.chessprogramming.org/Population_Count
"""
Count the number of 1 bits in a 64-bit integer using bitwise operations.
Parameters:
- x (uint64): The 64-bit integer.
Returns:
- int8: The number of 1 bits in the integer.
"""
k1 = 0x5555555555555555
k2 = 0x3333333333333333
k4 = 0x0f0f0f0f0f0f0f0f
kf = 0x0101010101010101
x = x - ((x >> 1) & k1)
x = (x & k2) + ((x >> 2) & k2)
x = (x + (x >> 4)) & k4
x = (x * kf) >> 56
return x
@njit(int8(uint64), cache = True)
def bit_scan_forward(bit_board):
# https://www.chessprogramming.org/BitScan
"""
Find the index of the least significant 1 bit in a 64-bit integer.
Parameters:
- bit_board (uint64): The 64-bit integer.
Returns:
- int8: The index of the least significant 1 bit.
"""
return count_bits((bit_board & -bit_board) - 1)
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_up(player_disks, opponent_disks, empty_squares):
potential = (player_disks >> 8) & opponent_disks
potential = (potential >> 8); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = (potential >> 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential >> 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential >> 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential >> 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential >> 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_up_right(player_disks, opponent_disks, empty_squares):
potential = ((player_disks >> 7) & RIGHT_MASK) & opponent_disks
potential = ((potential >> 7) & RIGHT_MASK); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 7) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 7) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 7) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 7) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 7) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_right(player_disks, opponent_disks, empty_squares):
potential = ((player_disks << 1) & RIGHT_MASK) & opponent_disks
potential = ((potential << 1) & RIGHT_MASK); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = ((potential << 1) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 1) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 1) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 1) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 1) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_down_right(player_disks, opponent_disks, empty_squares):
potential = ((player_disks << 9) & RIGHT_MASK) & opponent_disks
potential = ((potential << 9) & RIGHT_MASK); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = ((potential << 9) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 9) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 9) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 9) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 9) & RIGHT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_down(player_disks, opponent_disks, empty_squares):
potential = (player_disks << 8) & opponent_disks
potential = (potential << 8); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = (potential << 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential << 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential << 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential << 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = (potential << 8); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_down_left(player_disks, opponent_disks, empty_squares):
potential = ((player_disks << 7) & LEFT_MASK) & opponent_disks
potential = ((potential << 7) & LEFT_MASK); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = ((potential << 7) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 7) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 7) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 7) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential << 7) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_left(player_disks, opponent_disks, empty_squares):
potential = ((player_disks >> 1) & LEFT_MASK) & opponent_disks
potential = ((potential >> 1) & LEFT_MASK); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 1) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 1) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 1) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 1) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 1) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def validate_up_left(player_disks, opponent_disks, empty_squares):
potential = ((player_disks >> 9) & LEFT_MASK) & opponent_disks
potential = ((potential >> 9) & LEFT_MASK); valid_plays = potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 9) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 9) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 9) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 9) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
potential = ((potential >> 9) & LEFT_MASK); valid_plays |= potential & empty_squares; potential &= opponent_disks
return valid_plays
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def possible_moves(player_disks, opponent_disks, empty_squares):
# https://www.chessprogramming.org/Dumb7Fill
"""
Determine all possible moves for the current player.
Parameters:
- player_disks (uint64): Bitboard representing the current player's pieces.
- opponent_disks (uint64): Bitboard representing the opponent's pieces.
- empty_squares (uint64): Bitboard representing empty squares.
Returns:
- uint64: Bitboard representing all possible moves.
"""
return (validate_up(player_disks, opponent_disks, empty_squares) |
validate_up_right(player_disks, opponent_disks, empty_squares) |
validate_right(player_disks, opponent_disks, empty_squares) |
validate_down_right(player_disks, opponent_disks, empty_squares) |
validate_down(player_disks, opponent_disks, empty_squares) |
validate_down_left(player_disks, opponent_disks, empty_squares) |
validate_left(player_disks, opponent_disks, empty_squares) |
validate_up_left(player_disks, opponent_disks, empty_squares))
@njit(int8[::1](uint64), cache=True, nogil=True)
def get_moves_index(bitboard):
"""
Get the indices of all set bits in a bitboard.
Parameters:
- bitboard (uint64): The bitboard.
Returns:
- int8[::1]: Array of indices of set bits.
"""
indices = np.zeros(count_bits(bitboard), dtype=np.int8)
count = 0
while bitboard:
index = bit_scan_forward(bitboard)
indices[count] = index
count += 1
bitboard &= bitboard - uint64(1)
return indices
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_up(placement, player_disks, opponent_disks):
flipped_pieces = (placement >> 8) & opponent_disks
flipped_pieces |= (flipped_pieces >> 8) & opponent_disks
flipped_pieces |= (flipped_pieces >> 8) & opponent_disks
flipped_pieces |= (flipped_pieces >> 8) & opponent_disks
flipped_pieces |= (flipped_pieces >> 8) & opponent_disks
flipped_pieces |= (flipped_pieces >> 8) & opponent_disks
if ((flipped_pieces >> 8) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_up_right(placement, player_disks, opponent_disks):
flipped_pieces = ((placement >> 7) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 7) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 7) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 7) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 7) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 7) & RIGHT_MASK) & opponent_disks
if (((flipped_pieces >> 7) & RIGHT_MASK) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_right(placement, player_disks, opponent_disks):
flipped_pieces = ((placement << 1) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 1) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 1) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 1) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 1) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 1) & RIGHT_MASK) & opponent_disks
if (((flipped_pieces << 1) & RIGHT_MASK) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_down_right(placement, player_disks, opponent_disks):
flipped_pieces = ((placement << 9) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 9) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 9) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 9) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 9) & RIGHT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 9) & RIGHT_MASK) & opponent_disks
if (((flipped_pieces << 9) & RIGHT_MASK) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_down(placement, player_disks, opponent_disks):
flipped_pieces = (placement << 8) & opponent_disks
flipped_pieces |= (flipped_pieces << 8) & opponent_disks
flipped_pieces |= (flipped_pieces << 8) & opponent_disks
flipped_pieces |= (flipped_pieces << 8) & opponent_disks
flipped_pieces |= (flipped_pieces << 8) & opponent_disks
flipped_pieces |= (flipped_pieces << 8) & opponent_disks
if ((flipped_pieces << 8) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_down_left(placement, player_disks, opponent_disks):
flipped_pieces = ((placement << 7) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 7) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 7) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 7) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 7) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces << 7) & LEFT_MASK) & opponent_disks
if (((flipped_pieces << 7) & LEFT_MASK) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_left(placement, player_disks, opponent_disks):
flipped_pieces = ((placement >> 1) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 1) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 1) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 1) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 1) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 1) & LEFT_MASK) & opponent_disks
if (((flipped_pieces >> 1) & LEFT_MASK) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_up_left(placement, player_disks, opponent_disks):
flipped_pieces = ((placement >> 9) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 9) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 9) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 9) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 9) & LEFT_MASK) & opponent_disks
flipped_pieces |= ((flipped_pieces >> 9) & LEFT_MASK) & opponent_disks
if (((flipped_pieces >> 9) & LEFT_MASK) & player_disks) == 0:
return 0
return flipped_pieces
@njit(uint64(uint64, uint64, uint64), cache=True, nogil=True)
def place_disks(placement, player_disks, opponent_disks):
"""
Compute the bitboard of disks flipped when placing a disk.
Parameters:
- placement (uint64): Bitboard of the placement.
- player_disks (uint64): Bitboard representing the current player's pieces.
- opponent_disks (uint64): Bitboard representing the opponent's pieces.
Returns:
- uint64: Bitboard of the flipped disks.
"""
return (place_up(placement, player_disks, opponent_disks) |
place_up_right(placement, player_disks, opponent_disks) |
place_right(placement, player_disks, opponent_disks) |
place_down_right(placement, player_disks, opponent_disks) |
place_down(placement, player_disks, opponent_disks) |
place_down_left(placement, player_disks, opponent_disks) |
place_left(placement, player_disks, opponent_disks) |
place_up_left(placement, player_disks, opponent_disks))
@njit(uint64(UniTuple(uint64, 2), int8), cache=True)
def find_empty_neighbors_of_player(board, player_id):
"""
Find the empty neighboring cells of a player on the game board.
Parameters:
- board (UniTuple(uint64, 2)): A tuple containing two uint64 bitboards representing the game state.
- player_id (int8): The ID of the player whose empty neighboring cells are to be found.
Returns:
- uint64: A bitboard representing the empty neighboring cells of the specified player.
"""
# Get the bitboards of the current and opponent players
player_board = board[player_id - 1]
opponent_board = board[2 - player_id]
# Combine both players' bitboards
all_players_board = player_board | opponent_board
# Compute the set of empty cells
empty_board = all_players_board ^ 0xFFFFFFFFFFFFFFFF
# Compute empty neighboring cells
empty_neighbors = empty_board & (
((player_board >> 8)) | # Shift north
((player_board << 8)) | # Shift south
((player_board << 1) & RIGHT_MASK) | # Shift east
((player_board >> 1) & LEFT_MASK) | # Shift west
((player_board >> 7) & RIGHT_MASK) | # Shift northeast
((player_board >> 9) & LEFT_MASK) | # Shift northwest
((player_board << 9) & RIGHT_MASK) | # Shift southeast
((player_board << 7) & LEFT_MASK) # Shift southwest
)
return empty_neighbors
def visualize_bitboard(player1_pieces, player2_pieces=0):
board = np.zeros((8, 8), dtype=str)
board.fill('.')
for i in range(64):
if (uint64(player1_pieces) >> uint64(i)) & uint64(1):
row, col = divmod(i, 8)
board[row, col] = '1'
elif (uint64(player2_pieces) >> uint64(i)) & uint64(1):
row, col = divmod(i, 8)
board[row, col] = '2'
print(" A B C D E F G H")
print(" +----------------")
for i, row in enumerate(board):
print(f"{i}|{' '.join(row)}|")
print(" +----------------")
print(" A B C D E F G H")
@njit(UniTuple(uint64, 2)(UniTuple(uint64, 2), int8), cache = True)
def get_player_board(board, player_id):
"""
Get the current player's and opponent's bitboards.
Parameters:
- board (UniTuple(uint64, 2)): Tuple containing bitboards of both players.
- player_id (int8): The ID of the current player (1 or 2).
Returns:
- UniTuple(uint64, 2): Tuple containing the player's and opponent's bitboards.
"""
bb1, bb2 = board
if player_id == 1:
return bb1, bb2
return bb2, bb1
@njit(UniTuple(uint64, 2)(UniTuple(uint64, 2), int8, int8), cache = True)
def make_move(board, move, player_id):
"""
Make a move on the board.
Parameters:
- board (UniTuple(uint64, 2)): Tuple containing bitboards of both players.
- move (int8): The index of the move to make.
- player_id (int8): The ID of the player (1 or 2).
Returns:
- UniTuple(uint64, 2): Tuple containing the new bitboards after the move.
"""
player1, player2 = board
selected_square = uint64(1) << move
if player_id == 1:
flipped_disks = place_disks(selected_square, player1, player2)
new_player1_board = player1 | (selected_square | flipped_disks)
new_player2_board = player2 ^ flipped_disks
return new_player1_board, new_player2_board
flipped_disks = place_disks(selected_square, player2, player1)
new_player1_board = player1 ^ flipped_disks
new_player2_board = player2 | (selected_square | flipped_disks)
return new_player1_board, new_player2_board
@njit(int16(int8, UniTuple(uint64, 2), int8[::1]), cache=True)
def find_unstable_disks(player_id, board, opponent_moves):
"""
Identify how many unstable disks the player has.
Parameters:
player (int8): The player's ID (1 or 2).
board (UniTuple(uint64, 2)): The game board.
opponent_moves (int8[::1]): List of opponent moves.
Returns:
int16: The number of unstable disks
"""
unstable_disks = uint64(0)
player_board, _ = get_player_board(board, player_id)
# Simulate opponent moves to identify unstable disks
for move in opponent_moves:
simulated_board = make_move(board, move, player_id)
_, simulated_opponent_board = get_player_board(simulated_board, player_id)
unstable_disks |= (player_board & simulated_opponent_board)
return count_bits(unstable_disks)
@njit(int16(int8, UniTuple(uint64, 2), uint64), cache=True)
def find_stable_disks(player_id, board, adjacent_cells):
"""
Identify how many stable disks the player has.
Parameters:
board (UniTuple(uint64, 2)): The game board.
player (int16): The player's ID (1 or 2).
adjacent_cells (uint64): Bitboard representing adjacent cells to the player's disks.
Returns:
int16: The number of stable disks.
"""
fliped_disks = uint64(0)
player_board, opponent_board = get_player_board(board, player_id)
# Iterate over all possible adjacent cells
for i in range(64):
if adjacent_cells & (uint64(1) << i):
tmp_opponent = opponent_board | (adjacent_cells ^ (uint64(1) << i))
tmp_board = (player_board, tmp_opponent) if player_id == 1 else (tmp_opponent, player_board)
simulated_board = make_move(tmp_board, i, player_id)
_, simulated_opponent_board = get_player_board(simulated_board, player_id)
fliped_disks |= (player_board & simulated_opponent_board)
stable_disks = player_board & ~fliped_disks
return count_bits(stable_disks)