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use std::ptr::Unique;
use std::mem;
use std::ops::{Deref, DerefMut};
use std::marker::PhantomData;
use std::heap::{Alloc, Layout, Heap};
use std::sync::atomic::{AtomicUsize,AtomicU16};
use piece_move::BitMove;
pub type Key = u64;
#[derive(Clone,PartialEq)]
pub struct Entry {
pub partial_key: u16,
pub best_move: BitMove,
pub score: i16,
pub eval: i16,
pub depth: u8,
pub time_node_bound: NodeTypeTimeBound,
}
impl Entry {
pub fn place(&mut self, key: Key, best_move: BitMove, score: i16, eval: i16, depth: u8, node_type: NodeType, time_bound: u8) {
let partial_key = key.wrapping_shr(48) as u16;
if partial_key != self.partial_key {
self.best_move = best_move;
}
if partial_key != self.partial_key || node_type == NodeType::Exact {
self.partial_key = partial_key;
self.score = score;
self.eval = eval;
self.depth = depth;
self.time_node_bound = NodeTypeTimeBound::create(node_type, time_bound);
}
}
pub fn time(&self) -> u8 {
self.time_node_bound.data & TIME_MASK
}
pub fn node_type(&self) -> NodeType {
match self.time_node_bound.data & NODE_TYPE_MASK {
0 => NodeType::NoBound,
1 => NodeType::LowerBound,
2 => NodeType::UpperBound,
_ => NodeType::Exact,
}
}
pub fn time_value(&self, curr_time: u8) -> u8 {
let inner: u8 = (259 as u8).wrapping_add((curr_time).wrapping_sub(self.time_node_bound.data)) & 0b1111_1100;
(self.depth).wrapping_sub((inner).wrapping_mul(2 as u8))
}
}
#[derive(Copy, Clone, Eq, PartialEq)]
pub struct NodeTypeTimeBound {
data: u8
}
pub const TIME_MASK: u8 = 0b1111_1100;
pub const NODE_TYPE_MASK: u8 = 0b0000_0011;
impl NodeTypeTimeBound {
pub fn create(node_type: NodeType, time_bound: u8) -> Self {
NodeTypeTimeBound {
data: time_bound + (node_type as u8)
}
}
pub fn update_time(&mut self, time_bound: u8) {
self.data = (self.data & NODE_TYPE_MASK) | time_bound;
}
}
#[derive(Copy, Clone, Eq, PartialEq)]
#[repr(u8)]
pub enum NodeType {
NoBound = 0,
LowerBound = 1,
UpperBound = 2,
Exact = 3,
}
pub const CLUSTER_SIZE: usize = 3;
pub struct Cluster {
pub entry: [Entry; CLUSTER_SIZE],
pub padding: [u8; 2],
}
pub struct TT {
clusters: Unique<Cluster>,
cap: usize,
time_age: u8,
}
impl TT {
pub fn new_round_up(size: usize) -> Self {
TT::new(size.next_power_of_two())
}
fn new(size: usize) -> Self {
assert_eq!(size.count_ones(), 1);
assert!(size > 0);
TT {
clusters: alloc_room(size),
cap: size,
time_age: 0,
}
}
pub fn num_clusters(&self) -> usize {
self.cap
}
pub fn resize_round_up(mut self, size: usize) {
self.resize(size.next_power_of_two());
}
fn resize(&mut self, size: usize) {
assert_eq!(size.count_ones(), 1);
assert!(size > 0);
self.de_alloc();
self.re_alloc(size);
}
pub fn clear(&mut self) {
let size = self.cap;
self.resize(size);
}
pub fn new_search(&mut self) {
self.time_age = (self.time_age).wrapping_add(4);
}
pub fn time_age(&self) -> u8 {
self.time_age
}
pub fn probe(&self, key: Key) -> (bool, &mut Entry) {
let partial_key: u16 = (key).wrapping_shr(48) as u16;
unsafe {
let cluster: *mut Cluster = self.cluster(key);
let init_entry: *mut Entry = cluster_first_entry(cluster);
for i in 0..CLUSTER_SIZE {
let entry_ptr: *mut Entry = init_entry.offset(i as isize);
let entry: &mut Entry = &mut (*entry_ptr);
if entry.partial_key == 0 || entry.partial_key == partial_key {
if entry.time() != self.time_age && entry.partial_key != 0 {
entry.time_node_bound.update_time(self.time_age);
}
return (true, entry);
}
}
let mut replacement: *mut Entry = init_entry;
let mut replacement_score: u8 = (&*replacement).time_value(self.time_age);
for i in 1..CLUSTER_SIZE {
let entry_ptr: *mut Entry = init_entry.offset(i as isize);
let entry_score: u8 = (&*entry_ptr).time_value(self.time_age);
if entry_score < replacement_score {
replacement = entry_ptr;
replacement_score = replacement_score;
}
}
(false, &mut (*replacement))
}
}
pub fn cluster(&self, key: Key) -> *mut Cluster {
let index: usize = ((self.num_clusters() - 1) as u64 & key) as usize;
unsafe {
self.clusters.as_ptr().offset(index as isize)
}
}
fn re_alloc(&mut self, size: usize) {
unsafe {
self.clusters = alloc_room(size);
}
}
fn de_alloc(&self) {
unsafe {
Heap.dealloc(self.clusters.as_ptr() as *mut _,
Layout::array::<Cluster>(self.cap).unwrap());
}
}
}
impl Drop for TT {
fn drop(&mut self) {
self.de_alloc();
}
}
#[inline]
unsafe fn cluster_first_entry(cluster: *mut Cluster) -> *mut Entry {
mem::transmute::<*mut Cluster,*mut Entry>(cluster)
}
#[inline]
fn alloc_room(size: usize) -> Unique<Cluster> {
unsafe {
let ptr = Heap.alloc_zeroed(Layout::array::<Cluster>(size).unwrap());
let new_ptr = match ptr {
Ok(ptr) => ptr,
Err(err) => Heap.oom(err),
};
Unique::new(new_ptr as *mut Cluster).unwrap()
}
}
#[cfg(test)]
mod tests {
extern crate rand;
use tt::*;
use std::ptr::null;
const HALF_GIG: usize = 2 << 24;
const THIRTY_MB: usize = 2 << 20;
#[test]
fn tt_alloc_realloc() {
let size: usize = 8;
let tt = TT::new(size);
assert_eq!(tt.num_clusters(), size);
let key = create_key(32, 44);
let (found,entry) = tt.probe(key);
}
#[test]
fn tt_null_ptr() {
let size: usize = 2 << 20;
let mut tt = TT::new_round_up(size);
for x in 0..1_000_000 as u64 {
let key: u64 = rand::random::<u64>();
{
let (found, entry) = tt.probe(key);
entry.depth = (x % 0b1111_1111) as u8;
entry.partial_key = key.wrapping_shr(48) as u16;
assert_ne!((entry as * const _), null());
}
tt.new_search();
}
}
#[test]
fn tt_basic_insert() {
let mut tt = TT::new_round_up(THIRTY_MB);
let partial_key_1: u16 = 17773;
let key_index: u64 = 0x5556;
let key_1 = create_key(partial_key_1, 0x5556);
let (found, entry) = tt.probe(key_1);
assert!(found);
entry.partial_key = partial_key_1;
entry.depth = 2;
let (found, entry) = tt.probe(key_1);
assert!(found);
assert_eq!(entry.partial_key,partial_key_1);
assert_eq!(entry.depth,2);
let partial_key_2: u16 = 8091;
let partial_key_3: u16 = 12;
let key_2: u64 = create_key(partial_key_2, key_index);
let key_3: u64 = create_key(partial_key_3, key_index);
let (found, entry) = tt.probe(key_2);
assert!(found);
entry.partial_key = partial_key_2;
entry.depth = 3;
let (found, entry) = tt.probe(key_3);
assert!(found);
entry.partial_key = partial_key_3;
entry.depth = 6;
let partial_key_4: u16 = 18;
let key_4: u64 = create_key(partial_key_4, key_index);
let (found, entry) = tt.probe(key_4);
assert!(!found);
assert_eq!(entry.partial_key, partial_key_1);
assert_eq!(entry.depth, 2);
}
fn create_key(partial_key: u16, full_key: u64) -> u64 {
(partial_key as u64).wrapping_shl(48) | (full_key & 0x0000_FFFF_FFFF_FFFF)
}
}