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BitBishop Command Reference

This document lists the commands currently implemented by BitBishop's text interface (UCI + project-specific extensions).

The engine reads one command per line from stdin and writes responses to stdout.

Quick Start

Example interactive session:

uci
isready
position startpos moves e2e4 e7e5
go depth 4
quit

General Parsing Rules

  • Commands are tokenized using whitespace splitting.
  • Extra spaces/tabs/carriage returns are tolerated.
  • Empty lines are ignored.
  • Commands are case-sensitive (uci works, UCI does not).
  • A command is only processed when a newline is received.
  • Unknown commands are ignored silently.

Startup Output

When the loop starts, BitBishop prints a startup banner:

BitBishop <version> by <authors>.

This line is an engine banner, not a standard UCI response.

UCI Commands

uci

Initial UCI handshake.

Syntax:

uci

Response:

id name BitBishop
id author Hardcode (Baptiste Penot)
uciok

isready

Readiness probe.

Syntax:

isready

Response:

readyok

ucinewgame

Resets internal board state to the standard starting position.

Syntax:

ucinewgame

Response: none

position

Sets the current board state.

Syntax:

position startpos [moves <move1> <move2> ...]
position fen <piece-placement> <side-to-move> <castling> <en-passant> <halfmove> <fullmove> [moves <move1> <move2> ...]

Examples:

position startpos
position startpos moves e2e4 e7e5 g1f3
position fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

Behavior notes:

  • If startpos or fen is missing/invalid at parse level, the command is ignored.
  • After moves, moves are applied left-to-right.
  • If one move is invalid, processing stops at that move (earlier moves stay applied).
  • No explicit success/error output is emitted.

go

Starts search on the current position.

Syntax:

go [depth <n>] [movetime <ms>] [wtime <ms>] [btime <ms>] [winc <ms>] [binc <ms>] [infinite]

Implemented behavior (current state):

  • depth <n>: fixed-depth search.

  • infinite: iterative deepening until stop.

  • movetime <ms>: iterative deepening search limited by a per-move budget in milliseconds.

  • Non-positive movetime values are clamped to 1 ms.

  • movetime takes precedence over wtime/btime/winc/binc.

  • infinite takes precedence over every other limit, including movetime and depth.

  • If both depth and a time-based limit are provided, the current implementation runs the timed search path.

  • When movetime is not provided, time is estimated from the side-to-move clock: roughly remaining time divided across future moves, with increment added and a safety reserve kept aside.

  • If no argument is provided behind go, search defaults to infinite mode.

  • If depth is not provided and no time control is provided either, search defaults to infinite mode.

Response when search ends:

bestmove <uci-move>

stop

Requests the current search to stop.

Syntax:

stop

Behavior:

  • If a search is running, the worker is stopped and returns bestmove ....
  • If no search is running, nothing is printed.

quit

Stops search (if any) and exits the engine loop.

Syntax:

quit

Response: none

BitBishop Extended Commands (Non-UCI)

d

Displays board diagnostics for the current position.

Syntax:

d

Output includes:

  • ASCII board
  • FEN notation
  • Zobrist hash

help

Prints a project help/about message.

Syntax:

help

Response: multiline informational text.

bench

Runs a benchmark search on the current position (non-UCI extension).

Syntax:

bench [depth <n>] [movetime <ms>] [wtime <ms>] [btime <ms>] [winc <ms>] [binc <ms>] [infinite]

Implemented behavior (current state):

  • Uses the same limit parser as go.
  • depth <n> runs a fixed-depth benchmark.
  • movetime <ms> runs a time-limited benchmark using the same semantics as go.
  • If infinite is provided, benchmark mode internally converts to depth 10.
  • A bare bench command (no limits) is parsed as infinite, then converted internally to depth 10.
  • stop can still interrupt a running benchmark early.

Response when benchmark ends:

bench nodes <total> negamax_nodes <negamax> quiescence_nodes <quiescence> time(s) <seconds>s nps <nps>

Options Support Status

UCI setoption

Not implemented yet.

  • The engine currently does not expose configurable UCI options.
  • No option name ... lines are emitted in uci response.