zobrist: add zobrist hashing to nodes

For bishops, knights, rooks and queens that is.

Cargo.lock

@@ -1,13 +1,5 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-[[package]]
-name = "ahash"
-version = "0.3.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "const-random 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "ansi_term"
 version = "0.11.0"
@@ -31,11 +23,6 @@ name = "bitflags"
 version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "cfg-if"
-version = "0.1.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "clap"
 version = "2.33.1"
@@ -50,44 +37,6 @@ dependencies = [
  "vec_map 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "const-random"
-version = "0.1.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "const-random-macro 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro-hack 0.5.16 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "const-random-macro"
-version = "0.1.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "getrandom 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro-hack 0.5.16 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "dashmap"
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-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "ahash 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "num_cpus 1.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
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-name = "getrandom"
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-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.71 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasi 0.9.0+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "hermit-abi"
 version = "0.1.13"
@@ -101,20 +50,6 @@ name = "libc"
 version = "0.2.71"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "num_cpus"
-version = "1.13.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "hermit-abi 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.71 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "proc-macro-hack"
-version = "0.5.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "strsim"
 version = "0.8.0"
@@ -138,7 +73,6 @@ name = "vatu"
 version = "0.1.0"
 dependencies = [
  "clap 2.33.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "dashmap 3.11.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -146,11 +80,6 @@ name = "vec_map"
 version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "wasi"
-version = "0.9.0+wasi-snapshot-preview1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "winapi"
 version = "0.3.8"
@@ -171,25 +100,16 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
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-"checksum ahash 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "e8fd72866655d1904d6b0997d0b07ba561047d070fbe29de039031c641b61217"
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 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"

Cargo.toml

@@ -6,4 +6,3 @@ edition = "2018"
 
 [dependencies]
 clap = "2.33"
-dashmap = "3.11"

README.md

@@ -67,6 +67,8 @@ cp external/lichess-bot/config.yml.example /tmp/vatu-config/config.yml
 docker build -f res/docker/Dockerfile -t vatu .
 # Run with the config folder mounted at /config.
 docker run -v /tmp/vatu-config:/config -ti vatu
+# In the container, use the following command:
+python lichess-bot.py --config /config/config.yml
 ```
 
 
@@ -74,10 +76,12 @@ docker run -v /tmp/vatu-config:/config -ti vatu
 TODO
 ----
 
-- Support time constraints
-- Proper unmake mechanism instead of allocating boards like there is no tomorrow
-- Precompute some pieces moves, maybe
-- Transposition table that does not actually slows search down
-- Check Zobrist hashes for previous point
-- Actual bitboard
-- Multithreading (never)
+- [X] Support time constraints
+- [X] Unmake mechanism instead of allocating nodes like there is no tomorrow
+- [X] Precompute some pieces moves, maybe (done for knights)
+- [ ] Transposition table that does not actually slows search down
+- [ ] Check Zobrist hashes for previous point
+- [X] Actual bitboard
+- [ ] Some kind of move ordering could be great
+- [ ] Multithreading (never)
+- [ ] Avoid 3-fold repetitions when winning

res/scripts/gen_king_rays.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+"""Pre-compute king ras bitboards for each square."""
+
+TEMPLATE = """\
+/// Pre-computed king rays.
+pub const KING_RAYS: [Bitboard; 64] = [
+{}
+];
+"""
+
+DIRS = [(1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1), (0, -1), (1, -1)]
+
+def bit_pos(square):
+    return 1 << square
+
+def get_rays():
+    rays = []
+    for f in range(8):
+        for r in range(8):
+            bitboard = 0
+            for dir_f, dir_r in DIRS:
+                ray_f = f + dir_f
+                ray_r = r + dir_r
+                if ray_f < 0 or ray_f > 7 or ray_r < 0 or ray_r > 7:
+                    continue
+                bitboard |= bit_pos(ray_f * 8 + ray_r)
+            rays.append("    0b{:064b},".format(bitboard))
+    return rays
+
+print(TEMPLATE.format("\n".join(get_rays())))

res/scripts/gen_knight_rays.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+"""Pre-compute knight ray bitboards for each square."""
+
+TEMPLATE = """\
+/// Pre-computed knight rays.
+pub const KNIGHT_RAYS: [Bitboard; 64] = [
+{}
+];
+"""
+
+DIRS = [(1, 2), (2, 1), (2, -1), (1, -2), (-1, -2), (-2, -1), (-2, 1), (-1, 2)]
+
+def bit_pos(square):
+    return 1 << square
+
+def get_rays():
+    rays = []
+    for f in range(8):
+        for r in range(8):
+            bitboard = 0
+            for dir_f, dir_r in DIRS:
+                ray_f = f + dir_f
+                ray_r = r + dir_r
+                if ray_f < 0 or ray_f > 7 or ray_r < 0 or ray_r > 7:
+                    continue
+                bitboard |= bit_pos(ray_f * 8 + ray_r)
+            rays.append("    0b{:064b},".format(bitboard))
+    return rays
+
+print(TEMPLATE.format("\n".join(get_rays())))

res/scripts/gen_pawn_captures.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+"""Pre-compute pawn captures bitboards for each square."""
+
+TEMPLATE = """\
+/// Pre-computed pawn captures.
+pub const PAWN_CAPTURES: [[Bitboard; 64]; 2] = [
+    [
+{}
+    ],
+    [
+{}
+    ],
+];
+"""
+
+def bit_pos(square):
+    return 1 << square
+
+def get_captures():
+    both_captures = []
+    for direction in [1, -1]:
+        captures = []
+        for f in range(8):
+            for r in range(8):
+                bitboard = 0
+                prog_r = r + direction
+                if 0 < prog_r < 7:
+                    prev_f = f - 1
+                    if prev_f >= 0:
+                        bitboard |= bit_pos(prev_f * 8 + prog_r)
+                    next_f = f + 1
+                    if next_f <= 7:
+                        bitboard |= bit_pos(next_f * 8 + prog_r)
+                captures.append("        0b{:064b},".format(bitboard))
+        both_captures.append(captures)
+    return both_captures
+
+CAPTURES = get_captures()
+print(TEMPLATE.format("\n".join(CAPTURES[0]), "\n".join(CAPTURES[1])))

res/scripts/gen_pawn_progresses.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""Pre-compute pawn progress bitboards for each square."""
+
+TEMPLATE = """\
+/// Pre-computed pawn progresses.
+pub const PAWN_PROGRESSES: [[Bitboard; 64]; 2] = [
+    [
+{}
+    ],
+    [
+{}
+    ],
+];
+"""
+
+def bit_pos(square):
+    return 1 << square
+
+def get_progresses():
+    both_progresses = []
+    for direction in [1, -1]:
+        progresses = []
+        for f in range(8):
+            for r in range(8):
+                bitboard = 0
+                if 0 < r < 7:
+                    prog_r = r + direction
+                    bitboard |= bit_pos(f * 8 + prog_r)
+                    if direction == 1 and r == 1:
+                        bitboard |= bit_pos(f * 8 + prog_r + 1)
+                    elif direction == -1 and r == 6:
+                        bitboard |= bit_pos(f * 8 + (prog_r - 1))
+                progresses.append("        0b{:064b},".format(bitboard))
+        both_progresses.append(progresses)
+    return both_progresses
+
+PROGRESSES = get_progresses()
+print(TEMPLATE.format("\n".join(PROGRESSES[0]), "\n".join(PROGRESSES[1])))

res/scripts/gen_squares.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python3
+
+for f in range(8):
+    for r in range(8):
+        print("pub const {}{}: Pos = {};".format(chr(f + 65), r + 1, f * 8 + r))

res/scripts/gen_zobrist_keys.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""Generate Zobrist keys."""
+
+import random
+
+
+random.seed("vatu stop playing your queen first you have other pieces")
+
+TEMPLATE = """\
+pub const ZOBRIST_PIECES: [[[ZobristHash; 64]; 6]; 2] = [
+{}
+];
+
+pub const ZOBRIST_BLACK_TURN: ZobristHash = {};
+
+pub const ZOBRIST_CASTLE_WH_K: usize = 0;
+pub const ZOBRIST_CASTLE_WH_Q: usize = 1;
+pub const ZOBRIST_CASTLE_BL_K: usize = 2;
+pub const ZOBRIST_CASTLE_BL_Q: usize = 3;
+
+pub const ZOBRIST_CASTLES: [ZobristHash; 4] = [
+{}
+];
+
+pub const ZOBRIST_EN_PASSANT: [ZobristHash; 8] = [
+{}
+];
+"""
+
+
+def gen_hash():
+    return random.getrandbits(64)
+
+
+def gen_pieces_keys():
+    pieces_str = ""
+    for color in range(2):
+        pieces_str += "    [\n"
+        for piece in range(6):
+            pieces_str += "        [\n"
+            for square in range(64):
+                k = gen_hash()
+                pieces_str += "            {},\n".format(k)
+            pieces_str += "        ],\n"
+        pieces_str += "    ],\n"
+    return pieces_str
+
+
+print(
+    TEMPLATE.format(
+        gen_pieces_keys(),
+        gen_hash(),
+        "\n".join(["    {},".format(gen_hash()) for _ in range(4)]),
+        "\n".join(["    {},".format(gen_hash()) for _ in range(8)]),
+    )
+)

src/analysis.rs

@@ -7,7 +7,6 @@ use crate::board;
 use crate::engine;
 use crate::movement::Move;
 use crate::node::Node;
-use crate::notation;
 use crate::rules;
 use crate::stats;
 
@@ -104,27 +103,24 @@ impl Analyzer {
 
         if self.debug {
             self.log(format!("Analyzing node:\n{}", &self.node));
-            let moves = self.node.get_player_moves(true);
-            self.log(format!("Legal moves: {}", notation::move_list_to_string(&moves)));
+            let moves = self.node.get_player_moves();
+            self.log(format!("Legal moves: {}", Move::list_to_uci_string(&moves)));
             self.log(format!("Move time: {}", self.time_limit));
         }
 
         self.start_time = Some(Instant::now());
         self.current_per_second_timer = Some(Instant::now());
-        let (max_score, best_move) = self.negamax(&self.node.clone(), MIN_F32, MAX_F32, 0);
+        let (max_score, best_move) = self.negamax(&mut self.node.clone(), MIN_F32, MAX_F32, 0);
 
-        if best_move.is_some() {
-            let log_str = format!(
-                "Best move {} evaluated {}",
-                notation::move_to_string(&best_move.unwrap()), max_score
-            );
+        if let Some(m) = best_move {
+            let log_str = format!("Best move {} evaluated {}", m.to_uci_string(), max_score);
             self.log(log_str);
-            self.report_best_move(best_move);
+            self.report_best_move(Some(m));
         } else {
             // If no best move could be found, checkmate is unavoidable; send the first legal move.
             self.log("Checkmate is unavoidable.".to_string());
-            let moves = rules::get_player_moves(&self.node.board, &self.node.game_state, true);
-            let m = if moves.len() > 0 { Some(moves[0]) } else { None };
+            let moves = rules::get_player_moves(&mut self.node.board, &mut self.node.game_state);
+            let m = if moves.len() > 0 { Some(moves[0].clone()) } else { None };
             self.report_best_move(m);
         }
     }
@@ -135,7 +131,7 @@ impl Analyzer {
         self.time_limit = if args.move_time != -1 {
             args.move_time
         } else {
-            let (time, inc) = if board::is_white(self.node.game_state.color) {
+            let (time, inc) = if self.node.game_state.color == board::WHITE {
                 (args.white_time, args.white_inc)
             } else {
                 (args.black_time, args.black_inc)
@@ -162,7 +158,7 @@ impl Analyzer {
     /// lower score bound and `beta` the upper bound.
     fn negamax(
         &mut self,
-        node: &Node,
+        node: &mut Node,
         alpha: f32,
         beta: f32,
         depth: u32,
@@ -189,18 +185,21 @@ impl Analyzer {
         }
 
         // Get negamax for playable moves.
-        let moves = node.get_player_moves(true);
+        let mut moves = node.get_player_moves();
         let mut alpha = alpha;
         let mut best_score = MIN_F32;
         let mut best_move = None;
-        for m in moves {
-            let mut sub_node = node.clone();
-            sub_node.apply_move(&m);
-            let result = self.negamax(&sub_node, -beta, -alpha, depth + 1);
+        for m in &mut moves {
+            let hash_changes = node.apply_move(m);
+            let result = self.negamax(node, -beta, -alpha, depth + 1);
+            node.unmake_move(m, hash_changes);
             let score = -result.0;
+            if self.debug && depth == 0 {
+                self.log(format!("move {} evaluated {}", m.to_uci_string(), score));
+            }
             if score > best_score {
                 best_score = score;
-                best_move = Some(m);
+                best_move = Some(m.to_owned());
             }
             if best_score > alpha {
                 alpha = best_score;

src/castling.rs

@@ -1,19 +1,53 @@
 //! Castling flags.
 
-pub const CASTLING_WH_K: u8    = 0b00000001;
-pub const CASTLING_WH_Q: u8    = 0b00000010;
-pub const CASTLING_WH_MASK: u8 = 0b00000011;
-pub const CASTLING_BL_K: u8    = 0b00000100;
-pub const CASTLING_BL_Q: u8    = 0b00001000;
-pub const CASTLING_BL_MASK: u8 = 0b00001100;
-pub const CASTLING_K_MASK: u8  = 0b00000101;
-pub const CASTLING_Q_MASK: u8  = 0b00001010;
-pub const CASTLING_MASK: u8    = 0b00001111;
+use crate::board::{Bitboard, RANK_1, RANK_8};
 
-/// Castling sides parameters.
+pub type Castle = u8;
+
+pub const CASTLE_WH_K: Castle    = 0b00000001;
+pub const CASTLE_WH_Q: Castle    = 0b00000010;
+pub const CASTLE_WH_MASK: Castle = 0b00000011;
+pub const CASTLE_BL_K: Castle    = 0b00000100;
+pub const CASTLE_BL_Q: Castle    = 0b00001000;
+pub const CASTLE_BL_MASK: Castle = 0b00001100;
+pub const CASTLE_K_MASK: Castle  = 0b00000101;
+pub const CASTLE_Q_MASK: Castle  = 0b00001010;
+pub const CASTLE_MASK: Castle    = 0b00001111;
+
+/// Index castling masks with their color.
+pub const CASTLE_MASK_BY_COLOR: [Castle; 2] = [CASTLE_WH_MASK, CASTLE_BL_MASK];
+
+/// Index castling ranks with their color.
+pub const CASTLE_RANK_BY_COLOR: [i8; 2] = [RANK_1, RANK_8];
+
+pub const CASTLE_SIDE_K: usize = 0;
+pub const CASTLE_SIDE_Q: usize = 1;
+pub const NUM_CASTLE_SIDES: usize = 2;
+
+/// Index castling sides using CASTLE_SIDE_K and CASTLE_SIDE_Q.
+pub const CASTLE_SIDES: [Castle; 2] = [CASTLE_K_MASK, CASTLE_Q_MASK];
+
+/// Castle paths that must not be under attack, by color and side.
 ///
-/// For both sides, the 3-uple contains files that should be empty
-/// and not attacked, an optional file that should be empty for
-/// queen-side, and the castling side-mask.
-pub const CASTLING_SIDES: [([i8; 2], Option<i8>, u8); 2] =
-    [([5i8, 6i8], None, CASTLING_K_MASK), ([3i8, 2i8], Some(1i8), CASTLING_Q_MASK)];
+/// This includes the original king position, its target square and
+/// the square in between.
+pub const CASTLE_LEGALITY_PATHS: [[Bitboard; 2]; 2] = [
+    [
+        0b00000000_00000001_00000001_00000001_00000000_00000000_00000000_00000000,  // White Kside.
+        0b00000000_00000000_00000000_00000001_00000001_00000001_00000000_00000000,  // White Qside.
+    ], [
+        0b00000000_10000000_10000000_10000000_00000000_00000000_00000000_00000000,  // Black Kside.
+        0b00000000_00000000_00000000_10000000_10000000_10000000_00000000_00000000,  // Black Qside.
+    ]
+];
+
+/// Castle paths that must be empty.
+pub const CASTLE_MOVE_PATHS: [[Bitboard; 2]; 2] = [
+    [
+        0b00000000_00000001_00000001_00000000_00000000_00000000_00000000_00000000,  // White Kside.
+        0b00000000_00000000_00000000_00000000_00000001_00000001_00000001_00000000,  // White Qside.
+    ], [
+        0b00000000_10000000_10000000_00000000_00000000_00000000_00000000_00000000,  // Black Kside.
+        0b00000000_00000000_00000000_00000000_10000000_10000000_10000000_00000000,  // Black Qside.
+    ]
+];

src/engine.rs

@@ -11,9 +11,9 @@ use std::thread;
 use crate::analysis;
 use crate::board;
 use crate::castling;
-use crate::movement::{self, Move};
+use crate::fen;
+use crate::movement::Move;
 use crate::node::Node;
-use crate::notation;
 use crate::uci;
 
 /// Analysis engine.
@@ -62,6 +62,8 @@ pub enum Cmd {
     WorkerInfo(Vec<analysis::AnalysisInfo>),
     /// Send best move found by analysis worker.
     WorkerBestMove(Option<Move>),
+    /// Log current node.
+    LogNode,
 
     // Commands that can be sent by the engine.
 
@@ -123,7 +125,17 @@ impl Engine {
             // Workers commands.
             Cmd::Log(s) => self.reply(Cmd::Log(s.to_string())),
             Cmd::WorkerInfo(infos) => self.reply(Cmd::Info(infos.to_vec())),
-            Cmd::WorkerBestMove(m) => self.reply(Cmd::BestMove(*m)),
+            Cmd::WorkerBestMove(m) => self.reply(Cmd::BestMove(m.clone())),
+            // Other commands.
+            Cmd::LogNode => {
+                let mut s = vec!();
+                self.node.board.draw_to(&mut s);
+                self.reply(Cmd::Log(format!(
+                    "Current node:\n{}{}",
+                    String::from_utf8_lossy(&s),
+                    self.node.game_state
+                )));
+            }
             _ => eprintln!("Not an engine input command: {:?}", cmd),
         }
     }
@@ -141,29 +153,30 @@ impl Engine {
     /// Apply a FEN string to the engine state, replacing it.
     ///
     /// For speed purposes, it assumes values are always valid.
-    fn apply_fen(&mut self, fen: &notation::Fen) {
+    fn apply_fen(&mut self, fen: &fen::Fen) {
         // Placement.
-        self.node.board = board::new_from_fen(&fen.placement);
+        self.node.board = board::Board::new_from_fen(&fen.placement);
         // Color.
         match fen.color.chars().next().unwrap() {
-            'w' => self.node.game_state.color = board::SQ_WH,
-            'b' => self.node.game_state.color = board::SQ_BL,
+            'w' => self.node.game_state.color = board::WHITE,
+            'b' => self.node.game_state.color = board::BLACK,
             _ => {}
         };
         // Castling.
+        self.node.game_state.castling = 0;
         for c in fen.castling.chars() {
             match c {
-                'K' => self.node.game_state.castling |= castling::CASTLING_WH_K,
-                'Q' => self.node.game_state.castling |= castling::CASTLING_WH_Q,
-                'k' => self.node.game_state.castling |= castling::CASTLING_BL_K,
-                'q' => self.node.game_state.castling |= castling::CASTLING_BL_Q,
+                'K' => self.node.game_state.castling |= castling::CASTLE_WH_K,
+                'Q' => self.node.game_state.castling |= castling::CASTLE_WH_Q,
+                'k' => self.node.game_state.castling |= castling::CASTLE_BL_K,
+                'q' => self.node.game_state.castling |= castling::CASTLE_BL_Q,
                 _ => {}
             }
         }
         // En passant.
         self.node.game_state.en_passant = match fen.en_passant.as_ref() {
             "-" => None,
-            p => Some(board::pos(p)),
+            s => Some(board::sq_from_string(s)),
         };
         // Half moves.
         self.node.game_state.halfmove = fen.halfmove.parse::<i32>().ok().unwrap();
@@ -172,13 +185,10 @@ impl Engine {
     }
 
     /// Apply a series of moves to the current node.
-    fn apply_moves(&mut self, moves: &Vec<Move>) {
-        moves.iter().for_each(|m| self.apply_move(m));
+    fn apply_moves(&mut self, moves: &mut Vec<Move>) {
+        for m in moves.iter_mut() {
+            m.apply_to(&mut self.node.board, &mut self.node.game_state);
         }
-
-    /// Apply a move to the current node.
-    fn apply_move(&mut self, m: &Move) {
-        movement::apply_move_to(&mut self.node.board, &mut self.node.game_state, m);
     }
 
     /// Start working on board, returning the best move found.
@@ -221,11 +231,11 @@ impl Engine {
                     self.apply_fen(&fen);
                 },
                 uci::PositionArgs::Startpos => {
-                    let fen = notation::parse_fen(notation::FEN_START).unwrap();
+                    let fen = fen::parse_fen(fen::FEN_START).unwrap();
                     self.apply_fen(&fen);
                 },
                 uci::PositionArgs::Moves(moves) => {
-                    self.apply_moves(&moves);
+                    self.apply_moves(&mut moves.clone());
                 }
             }
         }

src/fen.rs

@@ -0,0 +1,55 @@
+//! Functions to parse FEN strings.
+
+use crate::board;
+
+pub const FEN_START: &str = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
+
+/// FEN notation for positions, split into fields.
+#[derive(Debug, Clone)]
+pub struct Fen {
+    pub placement: String,
+    pub color: String,
+    pub castling: String,
+    pub en_passant: String,
+    pub halfmove: String,
+    pub fullmove: String,
+}
+
+pub fn parse_fen(i: &str) -> Option<Fen> {
+    let fields: Vec<&str> = i.split_whitespace().collect();
+    parse_fen_fields(&fields)
+}
+
+pub fn parse_fen_fields(fields: &[&str]) -> Option<Fen> {
+    if fields.len() < 6 {
+        return None
+    }
+    Some(Fen {
+        placement: fields[0].to_string(),
+        color: fields[1].to_string(),
+        castling: fields[2].to_string(),
+        en_passant: fields[3].to_string(),
+        halfmove: fields[4].to_string(),
+        fullmove: fields[5].to_string(),
+    })
+}
+
+pub fn en_passant_to_string(ep: Option<board::Square>) -> String {
+    ep.and_then(|p| Some(board::sq_to_string(p))).unwrap_or("-".to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_fen() {
+        let fen_start = parse_fen(FEN_START).unwrap();
+        assert_eq!(&fen_start.placement, "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR");
+        assert_eq!(&fen_start.color, "w");
+        assert_eq!(&fen_start.castling, "KQkq");
+        assert_eq!(&fen_start.en_passant, "-");
+        assert_eq!(&fen_start.halfmove, "0");
+        assert_eq!(&fen_start.fullmove, "1");
+    }
+}

src/main.rs

@@ -4,12 +4,14 @@ pub mod analysis;
 pub mod board;
 pub mod castling;
 pub mod engine;
+pub mod fen;
 pub mod movement;
 pub mod node;
-pub mod notation;
+pub mod precomputed;
 pub mod rules;
 pub mod stats;
 pub mod uci;
+pub mod zobrist;
 
 fn main() {
     let args = App::new("Vatu")

src/movement.rs

@@ -1,230 +1,374 @@
 //! Move functions along with some castling helpers.
 
+use std::fmt;
+
 use crate::board::*;
 use crate::castling::*;
-use crate::rules;
-
-const START_WH_K_POS: Pos = pos("e1");
-const START_BL_K_POS: Pos = pos("e8");
+use crate::rules::GameState;
+use crate::zobrist::*;
 
 /// A movement, with before/after positions and optional promotion.
-pub type Move = (Pos, Pos, Option<u8>);
-
-/// Apply a move `m` to copies to `board` and `game_state`.
-///
-/// Can be used for conveniance but it's better to write in existing
-/// instances as often as possible using `apply_move_to`.
-pub fn apply_move(
-    board: &Board,
-    game_state: &rules::GameState,
-    m: &Move
-) -> (Board, rules::GameState) {
-    let mut new_board = board.clone();
-    let mut new_state = game_state.clone();
-    apply_move_to(&mut new_board, &mut new_state, m);
-    (new_board, new_state)
+#[derive(Clone, PartialEq)]
+pub struct Move {
+    /// Square from which a piece moves.
+    pub source: Square,
+    /// Square to which a piece moves.
+    pub dest: Square,
+    /// Promotion piece for pawns reaching the last rank.
+    pub promotion: Option<Piece>,
+    /// Captured piece, if any.
+    pub capture: Option<Piece>,
+    /// Castle options before the move. This is set when the move is first applied.
+    pub old_castles: Castle,
 }
 
-/// Update `board` and `game_state` to reflect the move `m`.
-///
-/// The board is updated with correct piece placement.
-///
-/// The game state is updated with the new player turn and the new
-/// castling options.
-pub fn apply_move_to(
-    board: &mut Board,
-    game_state: &mut rules::GameState,
-    m: &Move
-) {
-    // If a rook is taken, remove its castling option. Needs to be checked before we update board.
-    if m.1 == pos("a1") && get_square(board, &pos("a1")) == SQ_WH_R {
-        game_state.castling &= !CASTLING_WH_Q;
-    } else if m.1 == pos("h1") && get_square(board, &pos("h1")) == SQ_WH_R {
-        game_state.castling &= !CASTLING_WH_K;
-    } else if m.1 == pos("a8") && get_square(board, &pos("a8")) == SQ_BL_R {
-        game_state.castling &= !CASTLING_BL_Q;
-    } else if m.1 == pos("h8") && get_square(board, &pos("h8")) == SQ_BL_R {
-        game_state.castling &= !CASTLING_BL_K;
+impl fmt::Debug for Move {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.to_uci_string())
+    }
+}
+
+/// Null move string in UCI exchanges.
+pub const UCI_NULL_MOVE_STR: &str = "0000";
+
+impl Move {
+    /// Build a move from `source` to `dest`, no promotion.
+    pub const fn new(source: Square, dest: Square) -> Move {
+        Move { source, dest, promotion: None, capture: None, old_castles: 0 }
     }
 
-    // Update board and game state.
-    apply_move_to_board(board, m);
+    /// Build a move from `source` to `dest`, with a promotion.
+    pub const fn new_promotion(source: Square, dest: Square, promotion: Piece) -> Move {
+        Move { source, dest, promotion: Some(promotion), capture: None, old_castles: 0 }
+    }
+
+    /// Apply this move to `board` and `game_state`.
+    ///
+    /// Set automatic queen promotion for pawns, register captured
+    /// pieces and castle options.
+    pub fn apply_to(&mut self, board: &mut Board, game_state: &mut GameState) -> ZobristHash {
+        // Changes to a Zobrist hash due to this move.
+        let mut changes: ZobristHash = 0;
+        // Save current castling options to unmake later.
+        self.old_castles = game_state.castling;
+
+        let piece = board.get_piece_on(self.source);
+        if piece == KING {
+            // Handle king castling.
+            if let Some(castle) = self.get_castle() {
+                match castle {
+                    CASTLE_WH_K => {
+                        board.move_square(E1, G1);
+                        board.move_square(H1, F1);
+                        game_state.castling &= !CASTLE_WH_MASK;
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_K];
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_Q];
+                    }
+                    CASTLE_WH_Q => {
+                        board.move_square(E1, C1);
+                        board.move_square(A1, D1);
+                        game_state.castling &= !CASTLE_WH_MASK;
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_K];
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_Q];
+                    }
+                    CASTLE_BL_K => {
+                        board.move_square(E8, G8);
+                        board.move_square(H8, F8);
+                        game_state.castling &= !CASTLE_BL_MASK;
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_K];
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_Q];
+                    }
+                    CASTLE_BL_Q => {
+                        board.move_square(E8, C8);
+                        board.move_square(A8, D8);
+                        game_state.castling &= !CASTLE_BL_MASK;
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_K];
+                        changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_Q];
+                    }
+                    _ => { panic!("Invalid castle.") }
+                }
                 game_state.color = opposite(game_state.color);
+                changes ^= ZOBRIST_BLACK_TURN;
+                return changes
+            } else {
+                // If the king moved from starting square, remove it from castling options.
+                if self.source == E1 {
+                    game_state.castling &= !CASTLE_WH_MASK;
+                    changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_K];
+                    changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_Q];
+                }
+                else if self.source == E8 {
+                    game_state.castling &= !CASTLE_BL_MASK;
+                    changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_K];
+                    changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_Q];
+                }
+            }
+        }
 
-    // If the move is a castle, remove it from castling options.
-    if let Some(castle) = get_castle(m) {
+        // Record captured piece if any.
+        if !board.is_empty(self.dest) {
+            let captured_piece = board.get_piece_on(self.dest);
+            changes ^= get_piece_hash(opposite(game_state.color), captured_piece, self.dest);
+            self.capture = Some(captured_piece);
+        }
+
+        // Move the piece and apply promotion if any.
+        board.move_square(self.source, self.dest);
+        changes ^= get_piece_hash(game_state.color, piece, self.source);
+        if let Some(promotion_piece) = self.promotion {
+            board.set_piece(self.dest, PAWN, promotion_piece);
+            changes ^= get_piece_hash(game_state.color, promotion_piece, self.dest);
+        } else {
+            changes ^= get_piece_hash(game_state.color, piece, self.dest);
+        }
+
+        // If a rook moved, remove the castle side.
+        if self.source == A1 || self.dest == A1 {
+            game_state.castling &= !CASTLE_WH_Q;
+            changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_Q];
+        }
+        else if self.source == H1 || self.dest == H1 {
+            game_state.castling &= !CASTLE_WH_K;
+            changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_K];
+        }
+        else if self.source == A8 || self.dest == A8 {
+            game_state.castling &= !CASTLE_BL_Q;
+            changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_Q];
+        }
+        else if self.source == H8 || self.dest == H8 {
+            game_state.castling &= !CASTLE_BL_K;
+            changes ^= ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_K];
+        }
+
+        // Finally, switch to the opposing player in the game state.
+        game_state.color = opposite(game_state.color);
+        changes ^= ZOBRIST_BLACK_TURN;
+
+        // Return changes as a Zobrist hash.
+        changes
+    }
+
+    /// Unmake a move.
+    pub fn unmake(&self, board: &mut Board, game_state: &mut GameState) {
+        // Always restore previous castle options.
+        game_state.castling = self.old_castles;
+        // If the move is a castle, unmake it properly.
+        let piece = board.get_piece_on(self.dest);
+        if piece == KING {
+            if let Some(castle) = self.get_castle() {
                 match castle {
-            CASTLING_WH_K | CASTLING_WH_Q => game_state.castling &= !CASTLING_WH_MASK,
-            CASTLING_BL_K | CASTLING_BL_Q => game_state.castling &= !CASTLING_BL_MASK,
-            _ => {}
-        };
+                    CASTLE_WH_K => { board.move_square(G1, E1); board.move_square(F1, H1); }
+                    CASTLE_WH_Q => { board.move_square(C1, E1); board.move_square(D1, A1); }
+                    CASTLE_BL_K => { board.move_square(G8, E8); board.move_square(F8, H8); }
+                    CASTLE_BL_Q => { board.move_square(C8, E8); board.move_square(D8, A8); }
+                    _ => { panic!("Invalid castle.") }
                 }
-    // Else, check if the king or a rook moved to update castling options.
-    else {
-        let piece = get_square(board, &m.1);
-        if is_white(piece) && game_state.castling & CASTLING_WH_MASK != 0 {
-            match get_type(piece) {
-                SQ_K => {
-                    if m.0 == pos("e1") {
-                        game_state.castling &= !CASTLING_WH_MASK;
+                game_state.color = opposite(game_state.color);
+                return
             }
         }
-                SQ_R => {
-                    if m.0 == pos("a1") {
-                        game_state.castling &= !CASTLING_WH_Q;
-                    } else if m.0 == pos("h1") {
-                        game_state.castling &= !CASTLING_WH_K;
-                    }
-                }
-                _ => {}
-            }
-        } else if is_black(piece) && game_state.castling & CASTLING_BL_MASK != 0 {
-            match get_type(piece) {
-                SQ_K => {
-                    if m.0 == pos("e8") {
-                        game_state.castling &= !CASTLING_BL_MASK;
-                    }
-                }
-                SQ_R => {
-                    if m.0 == pos("a8") {
-                        game_state.castling &= !CASTLING_BL_Q;
-                    } else if m.0 == pos("h8") {
-                        game_state.castling &= !CASTLING_BL_K;
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-}
 
-/// Apply a move `m` into `board`.
-pub fn apply_move_to_board(board: &mut Board, m: &Move) {
-    if let Some(castle) = get_castle(m) {
+        // Move the piece back.
+        board.move_square(self.dest, self.source);
+
+        // Cancel the promotion.
+        if let Some(piece) = self.promotion {
+            board.set_piece(self.source, piece, PAWN);
+        }
+
+        // Restore captured piece.
+        if let Some(piece) = self.capture {
+            board.set_square(self.dest, game_state.color, piece);
+        }
+
+        // And switch back to previous player.
+        game_state.color = opposite(game_state.color);
+    }
+
+    /// Get the corresponding castling flag for this move.
+    pub fn get_castle(&self) -> Option<Castle> {
+        match (self.source, self.dest) {
+            (E1, C1) => Some(CASTLE_WH_Q),
+            (E1, G1) => Some(CASTLE_WH_K),
+            (E8, C8) => Some(CASTLE_BL_Q),
+            (E8, G8) => Some(CASTLE_BL_K),
+            _ => None,
+        }
+    }
+
+    /// Get the move for this castle.
+    pub fn get_castle_move(castle: u8) -> Move {
         match castle {
-            CASTLING_WH_K => {
-                move_piece(board, &START_WH_K_POS, &pos("g1"));
-                move_piece(board, &pos("h1"), &pos("f1"));
-            }
-            CASTLING_WH_Q => {
-                move_piece(board, &START_WH_K_POS, &pos("c1"));
-                move_piece(board, &pos("a1"), &pos("d1"));
-            }
-            CASTLING_BL_K => {
-                move_piece(board, &START_BL_K_POS, &pos("g8"));
-                move_piece(board, &pos("h8"), &pos("f8"));
-            }
-            CASTLING_BL_Q => {
-                move_piece(board, &START_BL_K_POS, &pos("c8"));
-                move_piece(board, &pos("a8"), &pos("d8"));
-            }
-            _ => {}
-        }
-    } else {
-        move_piece(board, &m.0, &m.1);
-        if let Some(prom_type) = m.2 {
-            let color = get_color(get_square(board, &m.1));
-            set_square(board, &m.1, color|prom_type);
-        }
-    }
-}
-
-/// Get the corresponding castling flag for this move.
-pub fn get_castle(m: &Move) -> Option<u8> {
-    if m.0 == pos("e1") {
-        if m.1 == pos("c1") {
-            Some(CASTLING_WH_Q)
-        } else if m.1 == pos("g1") {
-            Some(CASTLING_WH_K)
-        } else {
-            None
-        }
-    } else if m.0 == pos("e8") {
-        if m.1 == pos("c8") {
-            Some(CASTLING_BL_Q)
-        } else if m.1 == pos("g8") {
-            Some(CASTLING_BL_K)
-        } else {
-            None
-        }
-    } else {
-        None
-    }
-}
-
-/// Get the move for this castle.
-pub fn get_castle_move(castle: u8) -> Move {
-    match castle {
-        CASTLING_WH_Q => (pos("e1"), pos("c1"), None),
-        CASTLING_WH_K => (pos("e1"), pos("g1"), None),
-        CASTLING_BL_Q => (pos("e8"), pos("c8"), None),
-        CASTLING_BL_K => (pos("e8"), pos("g8"), None),
+            CASTLE_WH_Q => Move::new(E1, C1),
+            CASTLE_WH_K => Move::new(E1, G1),
+            CASTLE_BL_Q => Move::new(E8, C8),
+            CASTLE_BL_K => Move::new(E8, G8),
             _ => panic!("Illegal castling requested: {:08b}", castle),
         }
+    }
+
+    /// Parse an UCI move algebraic notation string to a Move.
+    pub fn from_uci_string(m_str: &str) -> Move {
+        Move {
+            source: sq_from_string(&m_str[0..2]),
+            dest: sq_from_string(&m_str[2..4]),
+            promotion: if m_str.len() == 5 {
+                Some(match m_str.as_bytes()[4] {
+                    b'b' => BISHOP,
+                    b'n' => KNIGHT,
+                    b'r' => ROOK,
+                    b'q' => QUEEN,
+                    _ => panic!("What is the opponent doing? This is illegal, I'm out."),
+                })
+            } else {
+                None
+            },
+            capture: None,
+            old_castles: 0,
+        }
+    }
+
+    /// Create a string containing the UCI algebraic notation of this move.
+    pub fn to_uci_string(&self) -> String {
+        let mut move_string = String::new();
+        move_string.push_str(&sq_to_string(self.source));
+        move_string.push_str(&sq_to_string(self.dest));
+        if let Some(piece) = self.promotion {
+            move_string.push(match piece {
+                QUEEN => 'q',
+                BISHOP => 'b',
+                KNIGHT => 'n',
+                ROOK => 'r',
+                _ => panic!("What are you doing? Promote to a legal piece.")
+            });
+        }
+        move_string
+    }
+
+    /// Debug only: create a space-separated string of moves.
+    pub(crate) fn list_to_uci_string(moves: &Vec<Move>) -> String {
+        moves.iter().map(|m| m.to_uci_string()).collect::<Vec<_>>().join(" ")
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::notation::parse_move;
 
     #[test]
-    fn test_apply_move_to_board() {
-        let mut b = new_empty();
+    fn test_apply_to_board() {
+        let mut b = Board::new_empty();
+        let mut gs = GameState::new();
 
         // Put 2 enemy knights on board.
-        set_square(&mut b, &pos("d4"), SQ_WH_N);
-        set_square(&mut b, &pos("f4"), SQ_BL_N);
+        b.set_square(D4, WHITE, KNIGHT);
+        b.set_square(F4, BLACK, KNIGHT);
         // Move white knight in a position attacked by black knight.
-        apply_move_to_board(&mut b, &(pos("d4"), pos("e6"), None));
-        assert_eq!(get_square(&b, &pos("d4")), SQ_E);
-        assert_eq!(get_square(&b, &pos("e6")), SQ_WH_N);
-        assert_eq!(num_pieces(&b), 2);
+        let mut m = Move::new(D4, E6);
+        m.apply_to(&mut b, &mut gs);
+        assert!(b.is_empty(D4));
+        assert_eq!(b.get_color_on(E6), WHITE);
+        assert_eq!(b.get_piece_on(E6), KNIGHT);
+        assert_eq!(count_bits(b.combined()), 2);
+        assert!(m.capture.is_none());
         // Sack it with black knight
-        apply_move_to_board(&mut b, &(pos("f4"), pos("e6"), None));
-        assert_eq!(get_square(&b, &pos("e6")), SQ_BL_N);
-        assert_eq!(num_pieces(&b), 1);
+        let mut m = Move::new(F4, E6);
+        m.apply_to(&mut b, &mut gs);
+        assert_eq!(b.get_color_on(E6), BLACK);
+        assert_eq!(b.get_piece_on(E6), KNIGHT);
+        assert_eq!(count_bits(b.combined()), 1);
+        assert_eq!(m.capture.unwrap(), KNIGHT);
     }
 
     #[test]
-    fn test_apply_move_to_castling() {
-        let mut b = new();
-        let mut gs = rules::GameState::new();
-        assert_eq!(gs.castling, CASTLING_MASK);
+    fn test_apply_to_castling() {
+        let mut b = Board::new();
+        let mut gs = GameState::new();
+        assert_eq!(gs.castling, CASTLE_MASK);
 
         // On a starting board, start by making place for all castles.
-        clear_square(&mut b, &pos("b1"));
-        clear_square(&mut b, &pos("c1"));
-        clear_square(&mut b, &pos("d1"));
-        clear_square(&mut b, &pos("f1"));
-        clear_square(&mut b, &pos("g1"));
-        clear_square(&mut b, &pos("b8"));
-        clear_square(&mut b, &pos("c8"));
-        clear_square(&mut b, &pos("d8"));
-        clear_square(&mut b, &pos("f8"));
-        clear_square(&mut b, &pos("g8"));
+        b.clear_square(B1, WHITE, KNIGHT);
+        b.clear_square(C1, WHITE, BISHOP);
+        b.clear_square(D1, WHITE, QUEEN);
+        b.clear_square(F1, WHITE, BISHOP);
+        b.clear_square(G1, WHITE, KNIGHT);
+        b.clear_square(B8, BLACK, KNIGHT);
+        b.clear_square(C8, BLACK, BISHOP);
+        b.clear_square(D8, BLACK, QUEEN);
+        b.clear_square(F8, BLACK, BISHOP);
+        b.clear_square(G8, BLACK, KNIGHT);
         // White queen-side castling.
-        apply_move_to(&mut b, &mut gs, &parse_move("e1c1"));
-        assert!(is_piece(get_square(&b, &pos("c1")), SQ_WH_K));
-        assert!(is_piece(get_square(&b, &pos("d1")), SQ_WH_R));
-        assert!(is_empty(&b, &pos("a1")));
-        assert!(is_empty(&b, &pos("e1")));
-        assert_eq!(gs.castling, CASTLING_BL_MASK);
+        Move::new(E1, C1).apply_to(&mut b, &mut gs);
+        assert_eq!(b.get_color_on(C1), WHITE);
+        assert_eq!(b.get_piece_on(C1), KING);
+        assert_eq!(b.get_color_on(D1), WHITE);
+        assert_eq!(b.get_piece_on(D1), ROOK);
+        assert!(b.is_empty(A1));
+        assert!(b.is_empty(E1));
+        assert_eq!(gs.castling, CASTLE_BL_MASK);
         // Black king-side castling.
-        apply_move_to(&mut b, &mut gs, &parse_move("e8g8"));
-        assert!(is_piece(get_square(&b, &pos("g8")), SQ_BL_K));
-        assert!(is_piece(get_square(&b, &pos("f8")), SQ_BL_R));
-        assert!(is_empty(&b, &pos("h8")));
-        assert!(is_empty(&b, &pos("e8")));
+        Move::new(E8, G8).apply_to(&mut b, &mut gs);
+        assert_eq!(b.get_color_on(G8), BLACK);
+        assert_eq!(b.get_piece_on(G8), KING);
+        assert_eq!(b.get_color_on(F8), BLACK);
+        assert_eq!(b.get_piece_on(F8), ROOK);
+        assert!(b.is_empty(H8));
+        assert!(b.is_empty(E8));
+        // At the end, no more castling options for both sides.
         assert_eq!(gs.castling, 0);
     }
 
+    #[test]
+    fn test_unmake() {
+        let mut b = Board::new_empty();
+        let mut gs = GameState::new();
+
+        // On unmaking a move, the white pawn is back to its original square.
+        b.set_square(D4, WHITE, PAWN);
+        let mut m = Move::new(D4, D5);
+        m.apply_to(&mut b, &mut gs);
+        m.unmake(&mut b, &mut gs);
+        assert!(b.is_empty(D5));
+        assert_eq!(b.get_color_on(D4), WHITE);
+        assert_eq!(b.get_piece_on(D4), PAWN);
+
+        // Castle options should be properly unmade.
+        b.set_square(E1, WHITE, KING);
+        b.set_square(H1, WHITE, ROOK);
+        let mut m = Move::new(E1, G1);
+        m.apply_to(&mut b, &mut gs);
+        assert!(!b.is_empty(G1));
+        assert!(!b.is_empty(F1));
+        assert_eq!(gs.castling, CASTLE_MASK ^ CASTLE_WH_MASK);
+        m.unmake(&mut b, &mut gs);
+        assert!(b.is_empty(G1));
+        assert!(b.is_empty(F1));
+        assert_eq!(b.get_piece_on(E1), KING);
+        assert_eq!(b.get_piece_on(H1), ROOK);
+        assert_eq!(gs.castling, CASTLE_MASK);
+    }
+
     #[test]
     fn test_get_castle() {
-        assert_eq!(get_castle(&parse_move("e1c1")), Some(CASTLING_WH_Q));
-        assert_eq!(get_castle(&parse_move("e1g1")), Some(CASTLING_WH_K));
-        assert_eq!(get_castle(&parse_move("e8c8")), Some(CASTLING_BL_Q));
-        assert_eq!(get_castle(&parse_move("e8g8")), Some(CASTLING_BL_K));
-        assert_eq!(get_castle(&parse_move("d2d4")), None);
+        assert_eq!(Move::new(E1, C1).get_castle(), Some(CASTLE_WH_Q));
+        assert_eq!(Move::new(E1, G1).get_castle(), Some(CASTLE_WH_K));
+        assert_eq!(Move::new(E8, C8).get_castle(), Some(CASTLE_BL_Q));
+        assert_eq!(Move::new(E8, G8).get_castle(), Some(CASTLE_BL_K));
+        assert_eq!(Move::new(D2, D4).get_castle(), None);
+    }
+
+    #[test]
+    fn test_to_uci_string() {
+        assert_eq!(Move::new(A1, D4).to_uci_string(), "a1d4");
+        assert_eq!(Move::new(H8, A8).to_uci_string(), "h8a8");
+        assert_eq!(Move::new_promotion(H7, H8, QUEEN).to_uci_string(), "h7h8q");
+        assert_eq!(Move::new_promotion(H7, H8, KNIGHT).to_uci_string(), "h7h8n");
+    }
+
+    #[test]
+    fn test_from_uci_string() {
+        assert_eq!(Move::from_uci_string("a1d4"), Move::new(A1, D4));
+        assert_eq!(Move::from_uci_string("a7a8q"), Move::new_promotion(A7, A8, QUEEN));
+        assert_eq!(Move::from_uci_string("a7a8r"), Move::new_promotion(A7, A8, ROOK));
     }
 }

src/node.rs

@@ -1,42 +1,52 @@
 use std::fmt;
-use std::hash::{Hash, Hasher};
 
 use crate::board;
-use crate::movement::{self, Move};
+use crate::movement::Move;
 use crate::rules;
 use crate::stats;
+use crate::zobrist;
 
 /// Analysis node: a board along with the game state.
-#[derive(Clone)]
+#[derive(Clone, PartialEq)]
 pub struct Node {
     /// Board for this node.
     pub board: board::Board,
     /// Game state.
     pub game_state: rules::GameState,
+    /// Zobrist hash of the node.
+    pub hash: zobrist::ZobristHash,
 }
 
 impl Node {
     /// Create a new node for an empty board and a new game state.
     pub fn new() -> Node {
         Node {
-            board: board::new_empty(),
+            board: board::Board::new_empty(),
             game_state: rules::GameState::new(),
+            hash: zobrist::get_new_game_hash(),
         }
     }
 
     /// Apply a move to this node.
-    pub fn apply_move(&mut self, m: &Move) {
-        movement::apply_move_to(&mut self.board, &mut self.game_state, m);
+    pub fn apply_move(&mut self, m: &mut Move) -> zobrist::ZobristHash {
+        let changes = m.apply_to(&mut self.board, &mut self.game_state);
+        self.hash ^= changes;
+        changes
+    }
+
+    pub fn unmake_move(&mut self, m: &Move, changes: zobrist::ZobristHash) {
+        m.unmake(&mut self.board, &mut self.game_state);
+        self.hash ^= changes;
     }
 
     /// Return player moves from this node.
-    pub fn get_player_moves(&self, commit: bool) -> Vec<Move> {
-        rules::get_player_moves(&self.board, &self.game_state, commit)
+    pub fn get_player_moves(&mut self) -> Vec<Move> {
+        rules::get_player_moves(&mut self.board, &mut self.game_state)
     }
 
     /// Compute stats for both players for this node.
-    pub fn compute_stats(&self) -> (stats::BoardStats, stats::BoardStats) {
-        stats::compute_stats(&self.board, &self.game_state)
+    pub fn compute_stats(&mut self) -> (stats::BoardStats, stats::BoardStats) {
+        stats::BoardStats::new_from(&mut self.board, &mut self.game_state)
     }
 }
 
@@ -53,29 +63,8 @@ impl fmt::Debug for Node {
 impl fmt::Display for Node {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut s = vec!();
-        board::draw(&self.board, &mut s);
+        self.board.draw_to(&mut s);
         let board_drawing = String::from_utf8_lossy(&s).to_string();
-        write!(
-            f,
-            "* Board:\n{}\n\
-             * Game state:\n{}",
-            board_drawing, self.game_state
-        )
-    }
-}
-
-impl PartialEq for Node {
-    fn eq(&self, other: &Self) -> bool {
-        self.board.iter().zip(other.board.iter()).all(|(a, b)| a == b)
-        && self.game_state == other.game_state
-    }
-}
-
-impl Eq for Node {}
-
-impl Hash for Node {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.board.iter().for_each(|square| state.write_u8(*square));
-        self.game_state.hash(state);
+        write!(f, "{}{}", board_drawing, self.game_state)
     }
 }

src/notation.rs

@@ -1,111 +0,0 @@
-//! Functions using various notations.
-
-use crate::board::*;
-use crate::movement::Move;
-
-pub const NULL_MOVE: &str = "0000";
-
-/// Create a string containing the UCI algebraic notation of this move.
-pub fn move_to_string(m: &Move) -> String {
-    let mut move_string = String::new();
-    move_string.push_str(&pos_string(&m.0));
-    move_string.push_str(&pos_string(&m.1));
-    if let Some(prom) = m.2 {
-        move_string.push(match prom {
-            SQ_Q => 'q',
-            SQ_B => 'b',
-            SQ_N => 'n',
-            SQ_R => 'r',
-            _ => panic!("What are you doing? Promote to a legal piece.")
-        });
-    }
-    move_string
-}
-
-/// Parse an UCI move algebraic notation string to a Move.
-pub fn parse_move(m_str: &str) -> Move {
-    let prom = if m_str.len() == 5 {
-        Some(match m_str.as_bytes()[4] {
-            b'b' => SQ_B,
-            b'n' => SQ_N,
-            b'r' => SQ_R,
-            b'q' => SQ_Q,
-            _ => panic!("What is the opponent doing? This is illegal, I'm out."),
-        })
-    } else {
-        None
-    };
-    (pos(&m_str[0..2]), pos(&m_str[2..4]), prom)
-}
-
-/// Create a space-separated string of moves. Used for debugging.
-pub fn move_list_to_string(moves: &Vec<Move>) -> String {
-    moves.iter().map(|m| move_to_string(m)).collect::<Vec<_>>().join(" ")
-}
-
-pub const FEN_START: &str = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
-
-/// FEN notation for positions, split into fields.
-#[derive(Debug, Clone)]
-pub struct Fen {
-    pub placement: String,
-    pub color: String,
-    pub castling: String,
-    pub en_passant: String,
-    pub halfmove: String,
-    pub fullmove: String,
-}
-
-pub fn parse_fen(i: &str) -> Option<Fen> {
-    let fields: Vec<&str> = i.split_whitespace().collect();
-    parse_fen_fields(&fields)
-}
-
-pub fn parse_fen_fields(fields: &[&str]) -> Option<Fen> {
-    if fields.len() < 6 {
-        return None
-    }
-    Some(Fen {
-        placement: fields[0].to_string(),
-        color: fields[1].to_string(),
-        castling: fields[2].to_string(),
-        en_passant: fields[3].to_string(),
-        halfmove: fields[4].to_string(),
-        fullmove: fields[5].to_string(),
-    })
-}
-
-pub fn en_passant_to_string(ep: Option<Pos>) -> String {
-    ep.and_then(|p| Some(pos_string(&p))).unwrap_or("-".to_string())
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_move_to_string() {
-        assert_eq!(move_to_string(&((0, 0), (3, 3), None)), "a1d4");
-        assert_eq!(move_to_string(&((7, 7), (0, 7), None)), "h8a8");
-        assert_eq!(move_to_string(&((7, 6), (7, 7), Some(SQ_Q))), "h7h8q");
-        assert_eq!(move_to_string(&((7, 6), (7, 7), Some(SQ_N))), "h7h8n");
-    }
-
-    #[test]
-    fn test_parse_move() {
-        assert_eq!(parse_move("a1d4"), ((0, 0), (3, 3), None));
-        assert_eq!(parse_move("a7a8q"), ((0, 6), (0, 7), Some(SQ_Q)));
-        assert_eq!(parse_move("a7a8r"), ((0, 6), (0, 7), Some(SQ_R)));
-    }
-
-    #[test]
-    fn test_parse_fen() {
-        let fen_start = parse_fen(FEN_START).unwrap();
-        assert_eq!(&fen_start.placement, "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR");
-        assert_eq!(&fen_start.color, "w");
-        assert_eq!(&fen_start.castling, "KQkq");
-        assert_eq!(&fen_start.en_passant, "-");
-        assert_eq!(&fen_start.halfmove, "0");
-        assert_eq!(&fen_start.fullmove, "1");
-    }
-}

src/stats.rs

@@ -1,7 +1,7 @@
 //! Board statistics used for heuristics.
 
 use crate::board::*;
-use crate::rules;
+use crate::rules::{GameState, get_player_moves};
 
 /// Storage for board pieces stats.
 #[derive(Debug, Clone, PartialEq)]
@@ -27,6 +27,20 @@ impl BoardStats {
         }
     }
 
+    /// Create two new BoardStats objects from the board, for both sides.
+    ///
+    /// The playing color will have its stats filled in the first
+    /// BoardStats object, its opponent in the second.
+    pub fn new_from(board: &mut Board, game_state: &mut GameState) -> (BoardStats, BoardStats) {
+        let mut stats = (BoardStats::new(), BoardStats::new());
+        let mut gs = game_state.clone();
+        stats.0.compute(board, &mut gs);
+        gs.color = opposite(gs.color);
+        stats.1.compute(board, &mut gs);
+        stats
+    }
+
+    /// Reset all stats to 0.
     pub fn reset(&mut self) {
         self.num_pawns = 0;
         self.num_bishops = 0;
@@ -39,6 +53,88 @@ impl BoardStats {
         self.num_isolated_pawns = 0;
         self.mobility = 0;
     }
+
+    /// Fill `stats` from given `board` and `game_state`.
+    ///
+    /// Only the current playing side stats are created,
+    /// prepare the game_state accordingly.
+    pub fn compute(&mut self, board: &mut Board, game_state: &mut GameState) {
+        self.reset();
+        let color = game_state.color;
+        // Compute mobility for all pieces.
+        self.mobility = get_player_moves(board, game_state).len() as i32;
+        // Compute amount of each piece.
+        for file in 0..8 {
+            for rank in 0..8 {
+                let square = sq(file, rank);
+                if board.is_empty(square) || board.get_color_on(square) != color {
+                    continue
+                }
+                match board.get_piece_on(square) {
+                    ROOK => self.num_rooks += 1,
+                    KNIGHT => self.num_knights += 1,
+                    BISHOP => self.num_bishops += 1,
+                    QUEEN => self.num_queens += 1,
+                    KING => self.num_kings += 1,
+                    PAWN => {
+                        self.num_pawns += 1;
+                        let pawn_bb = board.by_color_and_piece(color, PAWN);
+
+                        // Check for doubled pawns.
+                        let file_bb = FILES[file as usize];
+                        if (pawn_bb ^ bit_pos(square)) & file_bb != 0 {
+                            self.num_doubled_pawns += 1;
+                        }
+
+                        // Check for isolated and backward pawns.
+                        let (iso_on_prev_file, bw_on_prev_file) = if file > FILE_A {
+                            self.find_isolated_and_backward(pawn_bb, square, color, file - 1)
+                        } else {
+                            (true, true)
+                        };
+                        let (iso_on_next_file, bw_on_next_file) = if file < FILE_H {
+                            self.find_isolated_and_backward(pawn_bb, square, color, file + 1)
+                        } else {
+                            (true, true)
+                        };
+                        if iso_on_prev_file && iso_on_next_file {
+                            self.num_isolated_pawns += 1;
+                        }
+                        if bw_on_prev_file && bw_on_next_file {
+                            self.num_backward_pawns += 1;
+                        }
+                    },
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    /// Find isolated and backward pawns from `square` perspective.
+    ///
+    /// `bb` is the bitboard of `color`. `square` is only used to have
+    /// the reference rank. `file` is the file to inspect. To detect
+    /// isolated and backward pawns, `bb` should be the bitboard of
+    /// pawns of `color`.
+    fn find_isolated_and_backward(
+        &mut self,
+        bb: Bitboard,
+        square: Square,
+        color: Color,
+        file: i8
+    ) -> (bool, bool) {
+        if bb & FILES[file as usize] == 0 {
+            // If the piece is isolated for this file, it's backward as well.
+            (true, true)
+        } else {
+            let backward_file_bb = if color == WHITE {
+                before_on_file(file, sq_rank(square)) | bit_pos(sq(file, sq_rank(square)))
+            } else {
+                after_on_file(file, sq_rank(square)) | bit_pos(sq(file, sq_rank(square)))
+            };
+            (false, bb & backward_file_bb == 0)
+        }
+    }
 }
 
 impl std::fmt::Display for BoardStats {
@@ -54,126 +150,6 @@ impl std::fmt::Display for BoardStats {
     }
 }
 
-/// Create two new BoardStats objects from the board, for both sides.
-///
-/// See `compute_stats_into` for details.
-pub fn compute_stats(board: &Board, game_state: &rules::GameState) -> (BoardStats, BoardStats) {
-    let mut stats = (BoardStats::new(), BoardStats::new());
-    compute_stats_into(board, game_state, &mut stats);
-    stats
-}
-
-/// Compute stats for both the current player and its opponent.
-///
-/// The playing color will have its stats filled in the first
-/// BoardStats object, its opponent in the second.
-pub fn compute_stats_into(
-    board: &Board,
-    game_state: &rules::GameState,
-    stats: &mut (BoardStats, BoardStats)
-) {
-    let mut gs = game_state.clone();
-    compute_color_stats_into(board, &gs, &mut stats.0);
-    gs.color = opposite(gs.color);
-    compute_color_stats_into(board, &gs, &mut stats.1);
-}
-
-/// Fill `stats` from given `board` and `game_state`.
-///
-/// Only the current playing side stats are created,
-/// prepare the game_state accordingly.
-pub fn compute_color_stats_into(
-    board: &Board,
-    game_state: &rules::GameState,
-    stats: &mut BoardStats,
-) {
-    stats.reset();
-    let color = game_state.color;
-    // Compute mobility for all pieces.
-    stats.mobility = rules::get_player_moves(board, game_state, true).len() as i32;
-    // Compute amount of each piece.
-    for (piece, p) in get_piece_iterator(board) {
-        let (pos_f, pos_r) = p;
-        if piece == SQ_E || !is_color(piece, color) {
-            continue
-        }
-        match get_type(piece) {
-            SQ_R => stats.num_rooks += 1,
-            SQ_N => stats.num_knights += 1,
-            SQ_B => stats.num_bishops += 1,
-            SQ_Q => stats.num_queens += 1,
-            SQ_K => stats.num_kings += 1,
-            SQ_P => {
-                stats.num_pawns += 1;
-                let mut doubled = false;
-                let mut isolated = true;
-                let mut backward = true;
-                for r in 0..8 {
-                    // Check for doubled pawns.
-                    if
-                        !doubled &&
-                        is_piece(get_square(board, &(pos_f, r)), color|SQ_P) && r != pos_r
-                    {
-                        doubled = true;
-                    }
-                    // Check for isolated pawns.
-                    if
-                        isolated &&
-                        (
-                            // Check on the left file if not on a-file...
-                            (
-                                pos_f > POS_MIN &&
-                                is_piece(get_square(board, &(pos_f - 1, r)), color|SQ_P)
-                            ) ||
-                            // Check on the right file if not on h-file...
-                            (
-                                pos_f < POS_MAX &&
-                                is_piece(get_square(board, &(pos_f + 1, r)), color|SQ_P)
-                            )
-                        )
-                    {
-                        isolated = false;
-                    }
-                    // Check for backward pawns.
-                    if backward {
-                        if color == SQ_WH && r <= pos_r {
-                            if (
-                                pos_f > POS_MIN &&
-                                is_type(get_square(board, &(pos_f - 1, r)), SQ_P)
-                            ) || (
-                                pos_f < POS_MAX &&
-                                is_type(get_square(board, &(pos_f + 1, r)), SQ_P)
-                            ) {
-                                backward = false;
-                            }
-                        } else if color == SQ_BL && r >= pos_r {
-                            if (
-                                pos_f > POS_MIN &&
-                                is_type(get_square(board, &(pos_f - 1, r)), SQ_P)
-                            ) || (
-                                pos_f < POS_MAX &&
-                                is_type(get_square(board, &(pos_f + 1, r)), SQ_P)
-                            ) {
-                                backward = false;
-                            }
-                        }
-                    }
-                }
-                if doubled {
-                    stats.num_doubled_pawns += 1;
-                }
-                if isolated {
-                    stats.num_isolated_pawns += 1;
-                }
-                if backward {
-                    stats.num_backward_pawns += 1;
-                }
-            },
-            _ => {}
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -181,8 +157,8 @@ mod tests {
     #[test]
     fn test_compute_stats() {
         // Check that initial stats are correct.
-        let b = new();
-        let gs = rules::GameState::new();
+        let mut b = Board::new();
+        let mut gs = GameState::new();
         let initial_stats = BoardStats {
             num_pawns: 8,
             num_bishops: 2,
@@ -195,56 +171,54 @@ mod tests {
             num_isolated_pawns: 0,
             mobility: 20,
         };
-        let mut stats = compute_stats(&b, &gs);
-        eprintln!("{}", stats.0);
-        eprintln!("{}", stats.1);
+        let mut stats = BoardStats::new_from(&mut b, &mut gs);
         assert!(stats.0 == stats.1);
         assert!(stats.0 == initial_stats);
 
         // Check that doubled pawns are correctly counted.
-        let mut b = new_empty();
-        set_square(&mut b, &pos("d4"), SQ_WH_P);
-        set_square(&mut b, &pos("d6"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        let mut b = Board::new_empty();
+        b.set_square(D4, WHITE, PAWN);
+        b.set_square(D6, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 2);
         // Add a pawn on another file, no changes expected.
-        set_square(&mut b, &pos("e6"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        b.set_square(E6, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 2);
         // Add a pawn backward in the d-file: there are now 3 doubled pawns.
-        set_square(&mut b, &pos("d2"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        b.set_square(D2, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 3);
 
         // Check that isolated and backward pawns are correctly counted.
         assert_eq!(stats.0.num_isolated_pawns, 0);
         assert_eq!(stats.0.num_backward_pawns, 2);  // A bit weird?
         // Protect d4 pawn with a friend in e3: it is not isolated nor backward anymore.
-        set_square(&mut b, &pos("e3"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        b.set_square(E3, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 5);
         assert_eq!(stats.0.num_isolated_pawns, 0);
         assert_eq!(stats.0.num_backward_pawns, 1);
         // Add an adjacent friend to d2 pawn: no pawns are left isolated or backward.
-        set_square(&mut b, &pos("c2"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        b.set_square(C2, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 5);
         assert_eq!(stats.0.num_isolated_pawns, 0);
         assert_eq!(stats.0.num_backward_pawns, 0);
         // Add an isolated/backward white pawn in a far file.
-        set_square(&mut b, &pos("a2"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        b.set_square(A2, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 5);
         assert_eq!(stats.0.num_isolated_pawns, 1);
         assert_eq!(stats.0.num_backward_pawns, 1);
 
         // Check for pawns that are backward but not isolated.
-        let mut b = new_empty();
+        let mut b = Board::new_empty();
         // Here, d4 pawn protects both e5 and e3, but it is backward.
-        set_square(&mut b, &pos("d4"), SQ_WH_P);
-        set_square(&mut b, &pos("e5"), SQ_WH_P);
-        set_square(&mut b, &pos("e3"), SQ_WH_P);
-        compute_color_stats_into(&b, &gs, &mut stats.0);
+        b.set_square(D4, WHITE, PAWN);
+        b.set_square(E5, WHITE, PAWN);
+        b.set_square(E3, WHITE, PAWN);
+        stats.0.compute(&mut b, &mut gs);
         assert_eq!(stats.0.num_doubled_pawns, 2);
         assert_eq!(stats.0.num_isolated_pawns, 0);
         assert_eq!(stats.0.num_backward_pawns, 1);

src/uci.rs

@@ -7,8 +7,8 @@ use std::thread;
 
 use crate::analysis::AnalysisInfo;
 use crate::engine;
-use crate::movement::Move;
-use crate::notation;
+use crate::fen;
+use crate::movement::{Move, UCI_NULL_MOVE_STR};
 
 const VATU_NAME: &str = env!("CARGO_PKG_NAME");
 const VATU_AUTHORS: &str = env!("CARGO_PKG_AUTHORS");
@@ -57,6 +57,10 @@ pub enum UciCmd {
     Position(Vec<PositionArgs>),
     Go(Vec<GoArgs>),
     Quit,
+
+    // Unofficial commands mostly for debugging.
+    VatuNode,
+
     Unknown(String),
 }
 
@@ -64,7 +68,7 @@ pub enum UciCmd {
 #[derive(Debug, Clone)]
 pub enum PositionArgs {
     Startpos,
-    Fen(notation::Fen),
+    Fen(fen::Fen),
     Moves(Vec<Move>),
 }
 
@@ -198,6 +202,9 @@ impl Uci {
                 self.send_engine_command(engine::Cmd::Stop);
             },
             UciCmd::Quit => return false,
+            UciCmd::VatuNode => {
+                self.send_engine_command(engine::Cmd::LogNode);
+            }
             UciCmd::Unknown(c) => { self.log(format!("Unknown command: {}", c)); }
         }
         true
@@ -271,7 +278,7 @@ impl Uci {
                     s.push_str(&format!(" nps {}", n));
                 }
                 AnalysisInfo::CurrentMove(m) => {
-                    s.push_str(&format!(" currmove {}", notation::move_to_string(m)));
+                    s.push_str(&format!(" currmove {}", m.to_uci_string()));
                 }
             }
         }
@@ -280,11 +287,10 @@ impl Uci {
 
     /// Send best move.
     fn send_bestmove(&mut self, m: &Option<Move>) {
-        let move_str = match m {
-            Some(m) => notation::move_to_string(m),
-            None => notation::NULL_MOVE.to_string(),
-        };
-        self.send(&format!("bestmove {}", move_str));
+        self.send(&format!(
+            "bestmove {}",
+            if let Some(m) = m { m.to_uci_string() } else { UCI_NULL_MOVE_STR.to_string() }
+        ));
     }
 }
 
@@ -292,6 +298,9 @@ impl Uci {
 // UCI command parsers
 
 /// Parse an UCI command.
+///
+/// Handle main UCI commands: position, go, etc. The command "p" is an
+/// alias to "position".
 fn parse_command(s: &str) -> UciCmd {
     if s.len() == 0 {
         return UciCmd::Unknown("Empty command.".to_string());
@@ -303,9 +312,10 @@ fn parse_command(s: &str) -> UciCmd {
         "isready" => UciCmd::IsReady,
         "ucinewgame" => UciCmd::UciNewGame,
         "stop" => UciCmd::Stop,
-        "position" => parse_position_command(&fields[1..]),
+        "position" | "p" => parse_position_command(&fields[1..]),
         "go" => parse_go_command(&fields[1..]),
         "quit" => UciCmd::Quit,
+        "vatunode" => UciCmd::VatuNode,
         c => UciCmd::Unknown(c.to_string()),
     }
 }
@@ -319,7 +329,7 @@ fn parse_position_command(fields: &[&str]) -> UciCmd {
         match fields[i] {
             // Subcommand "fen" is followed by a FEN string.
             "fen" => {
-                if let Some(fen) = notation::parse_fen_fields(&fields[i + 1 .. i + 7]) {
+                if let Some(fen) = fen::parse_fen_fields(&fields[i + 1 .. i + 7]) {
                     subcommands.push(PositionArgs::Fen(fen))
                 } else {
                     return UciCmd::Unknown(format!("Bad format for position fen"))
@@ -332,7 +342,7 @@ fn parse_position_command(fields: &[&str]) -> UciCmd {
             "moves" => {
                 let mut moves = vec!();
                 while i + 1 < num_fields {
-                    moves.push(notation::parse_move(fields[i + 1]));
+                    moves.push(Move::from_uci_string(fields[i + 1]));
                     i += 1;
                 }
                 subcommands.push(PositionArgs::Moves(moves));

src/zobrist.rs

@@ -0,0 +1,49 @@
+//! Functions related to Zobrist hashes.
+
+use crate::board::*;
+
+pub type ZobristHash = u64;
+
+pub fn get_new_game_hash() -> ZobristHash {
+    return
+          get_piece_hash(WHITE, ROOK, A1)
+        ^ get_piece_hash(WHITE, KNIGHT, B1)
+        ^ get_piece_hash(WHITE, BISHOP, C1)
+        ^ get_piece_hash(WHITE, QUEEN, D1)
+        ^ get_piece_hash(WHITE, KING, E1)
+        ^ get_piece_hash(WHITE, BISHOP, F1)
+        ^ get_piece_hash(WHITE, KNIGHT, G1)
+        ^ get_piece_hash(WHITE, ROOK, H1)
+        ^ get_piece_hash(WHITE, PAWN, A2)
+        ^ get_piece_hash(WHITE, PAWN, B2)
+        ^ get_piece_hash(WHITE, PAWN, C2)
+        ^ get_piece_hash(WHITE, PAWN, D2)
+        ^ get_piece_hash(WHITE, PAWN, E2)
+        ^ get_piece_hash(WHITE, PAWN, F2)
+        ^ get_piece_hash(WHITE, PAWN, G2)
+        ^ get_piece_hash(WHITE, PAWN, H2)
+        ^ get_piece_hash(BLACK, PAWN, A7)
+        ^ get_piece_hash(BLACK, PAWN, B7)
+        ^ get_piece_hash(BLACK, PAWN, C7)
+        ^ get_piece_hash(BLACK, PAWN, D7)
+        ^ get_piece_hash(BLACK, PAWN, E7)
+        ^ get_piece_hash(BLACK, PAWN, F7)
+        ^ get_piece_hash(BLACK, PAWN, G7)
+        ^ get_piece_hash(BLACK, PAWN, H7)
+        ^ get_piece_hash(BLACK, ROOK, A8)
+        ^ get_piece_hash(BLACK, KNIGHT, B8)
+        ^ get_piece_hash(BLACK, BISHOP, C8)
+        ^ get_piece_hash(BLACK, QUEEN, D8)
+        ^ get_piece_hash(BLACK, KING, E8)
+        ^ get_piece_hash(BLACK, BISHOP, F8)
+        ^ get_piece_hash(BLACK, KNIGHT, G8)
+        ^ get_piece_hash(BLACK, ROOK, H8)
+        ^ ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_K]
+        ^ ZOBRIST_CASTLES[ZOBRIST_CASTLE_WH_Q]
+        ^ ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_K]
+        ^ ZOBRIST_CASTLES[ZOBRIST_CASTLE_BL_Q]
+}
+
+pub fn get_piece_hash(color: Color, piece: Piece, square: Square) -> ZobristHash {
+    ZOBRIST_PIECES[color][piece][square as usize]
+}