Pawnfuddle

Pawnfuddle – High-Precision Chess960 (Fischer Random) Generator

Pawnfuddle is a lightweight CLI tool that generates valid Chess960 starting positions using the official Scharnagl's Algorithm. It maps every possible position to a unique ID (0-959), ensuring mathematical determinism and compatibility with international tournament standards.

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Features

• Scharnagl’s Algorithm: Direct mapping of IDs (0-959) to positions. No more "shuffling and praying" for valid bishops.
• Deterministic Generation: Generate specific positions via --id for tournaments or study.
• Engine Ready: Full FEN string output compatible with Stockfish and modern chess GUIs.
• Terminal Optimized: Clean ASCII board visualization with "Flip" support for black-side perspective.
• Zero Dependencies: Pure Python 3. Works on Linux, BSD, and macOS out of the box.

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Installation

1. Clone the repository:

git clone [https://github.com/Cyber-idea12/Pawnfuddle.git](https://github.com/Cyber-idea12/Pawnfuddle.git)
cd Pawnfuddle

2. Run directly:

python3 pawnfuddle.py [flags]

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Usage

Generate a random Chess960 position

python3 pawnfuddle.py

Generate a specific position by ID (0-959)

Example: ID 518 is the classical chess starting position.

python3 pawnfuddle.py --id 518

Generate multiple positions

python3 pawnfuddle.py --count 5

Output FEN strings only

python3 pawnfuddle.py --fen

Use a seed for reproducibility

python3 pawnfuddle.py --seed 1800 --count 3

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CLI Flags Summary

Flag	Type	Description
--id ID	int	Fetch a specific position (0-959).
--count N	int	Number of positions to generate (default=1).
--fen	bool	Print FEN only, skip ASCII board.
--ascii	bool	Force ASCII board print (default if --fen not used).
--seed S	int	Random seed for reproducible random IDs.
--flip	bool	Flip board (Perspective from the Black side).

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Example Output

ASCII Board with ID

--- Chess960 Position ID: 214 ---
b n n q r k r b
p p p p p p p p
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
P P P P P P P P
B N N Q R K R B
ID = 214

FEN String

bnnqrkrb/pppppppp/8/8/8/8/PPPPPPPP/BNNQRKRB w KQkq - 0 1

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Technical Note

Pawnfuddle ensures the two core rules of Chess960 are always met:

1. Bishops must be on opposite-colored squares.
2. The King must be placed on a square between the two Rooks to allow for legal castling.

License

This project is licensed under the MIT License.