89 lines
No EOL
3.4 KiB
Python
89 lines
No EOL
3.4 KiB
Python
#!/usr/bin/env python3
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def generate_pawn_attacked_by():
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"""
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Generates a list of 64 u64 bitboards for each color (White, Black),
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where each bitboard represents the squares FROM WHICH a pawn
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can attack a given TARGET square.
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Uses Little-Endian File-Rank (LEFR) mapping: A1=0, H1=7, A2=8, ..., H8=63.
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Returns:
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[[u64; 64]; 2] (represented as a list of two lists)
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Index 0: White attackers (squares where a White pawn attacks the target)
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Index 1: Black attackers (squares where a Black pawn attacks the target)
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"""
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# all_attacks[0] = White, all_attacks[1] = Black
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all_attacks = [[], []]
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for sq in range(64):
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rank = sq // 8
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file = sq % 8
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white_attackers_bb = 0
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black_attackers_bb = 0
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# --- White Attackers (Index 0) ---
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# A white pawn attacks "up" the board to reach the target square 'sq'.
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# This means the attacking pawn must be "below" 'sq'.
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# We only check if the target is not on the 1st rank
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if rank > 0:
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# Attacker from Down-Left (relative to target sq)
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# Not possible if target is on the A-file
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if file > 0:
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white_attackers_bb |= (1 << (sq - 9))
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# Attacker from Down-Right (relative to target sq)
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# Not possible if target is on the H-file
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if file < 7:
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white_attackers_bb |= (1 << (sq - 7))
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# --- Black Attackers (Index 1) ---
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# A black pawn attacks "down" the board to reach the target square 'sq'.
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# This means the attacking pawn must be "above" 'sq'.
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# We only check if the target is not on the 8th rank
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if rank < 7:
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# Attacker from Up-Left (relative to target sq)
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# Not possible if target is on the A-file
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if file > 0:
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black_attackers_bb |= (1 << (sq + 7))
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# Attacker from Up-Right (relative to target sq)
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# Not possible if target is on the H-file
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if file < 7:
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black_attackers_bb |= (1 << (sq + 9))
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all_attacks[0].append(white_attackers_bb)
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all_attacks[1].append(black_attackers_bb)
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return all_attacks
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def print_rust_array(attacks_by_color, const_name):
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"""
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Prints the list of attack bitboards as a nested Rust array.
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"""
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print(f"pub const {const_name}: [[u64; 64]; 2] = [")
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# --- Print White Attacks ---
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print(" [ // Color 0: White (Squares a White pawn attacks FROM)")
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for i, attacks_bb in enumerate(attacks_by_color[0]):
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raw_binary_string = f"{attacks_bb:064b}"
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chunks = [raw_binary_string[i:i+8] for i in range(0, 64, 8)]
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binary_string = f"0b{'_'.join(chunks)}"
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print(f" {binary_string}, // Target Square {i} ({'ABCDEFGH'[i%8]}{i//8 + 1})")
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print(" ],")
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# --- Print Black Attacks ---
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print(" [ // Color 1: Black (Squares a Black pawn attacks FROM)")
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for i, attacks_bb in enumerate(attacks_by_color[1]):
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raw_binary_string = f"{attacks_bb:064b}"
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chunks = [raw_binary_string[i:i+8] for i in range(0, 64, 8)]
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binary_string = f"0b{'_'.join(chunks)}"
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print(f" {binary_string}, // Target Square {i} ({'ABCDEFGH'[i%8]}{i//8 + 1})")
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print(" ]")
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print("];")
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if __name__ == "__main__":
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attacks = generate_pawn_attacked_by()
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print_rust_array(attacks, "ATTACKING_PAWNS") |