midgame.c File Reference

#include "search.h"
#include "bit.h"
#include "options.h"
#include "stats.h"
#include "ybwc.h"
#include "settings.h"
#include <assert.h>
#include <math.h>

Macros
#define	RCD   0.5

Functions
int	search_eval_0 (Search *search)
	evaluate a midgame position with the evaluation function. More...
int	search_eval_1 (Search *search, const int alpha, int beta)
	Evaluate a position at depth 1. More...
int	search_eval_2 (Search *search, int alpha, const int beta)
	Evaluate a position at depth 2. More...
static void	search_update_probcut (Search *search, const NodeType node_type)
static void	search_restore_probcut (Search *search, const NodeType node_type, const int selectivity)
static bool	search_probcut (Search *search, const int alpha, const int depth, Node *parent, int *value)
	Probcut. More...
int	NWS_shallow (Search *search, const int alpha, int depth, HashTable *hash_table)
	Evaluate a midgame position with a Null Window Search algorithm. More...
int	PVS_shallow (Search *search, int alpha, int beta, int depth)
	Evaluate a midgame position at shallow depth. More...
int	NWS_midgame (Search *search, const int alpha, int depth, Node *parent)
	Evaluate a midgame position with a Null Window Search algorithm. More...
int	PVS_midgame (Search *search, const int alpha, const int beta, int depth, Node *parent)
	Evaluate a position with a deep Principal Variation Search algorithm. More...

Detailed Description

Search near the end of the game.

Date

1998 - 2017

Author

Richard Delorme

Version

4.4

Macro Definition Documentation

RCD

#define RCD   0.5

macro RCD : set to 0.0 if -rcd is added to the icc compiler

Function Documentation

NWS_midgame()

int NWS_midgame	(	Search *	search,
		const int	alpha,
		int	depth,
		Node *	parent
	)

Evaluate a midgame position with a Null Window Search algorithm.

This function is used when there are still many empty squares on the board. Move ordering, hash table cutoff, enhanced transposition cutoff, etc. are used in order to diminish the size of the tree to analyse, but at the expense of a slower speed.

Parameters

search	Search.
alpha	Alpha bound.
depth	Depth.
parent	Parent node.

Returns

A score, as a disc difference.

NWS_shallow()

int NWS_shallow	(	Search *	search,
		const int	alpha,
		int	depth,
		HashTable *	hash_table
	)

Evaluate a midgame position with a Null Window Search algorithm.

This function is used when there are still many empty squares on the board. Move ordering, hash table cutoff, enhanced transposition cutoff, etc. are used in order to diminish the size of the tree to analyse, but at the expense of a slower speed.

Parameters

search	search.
alpha	lower bound.
depth	Search remaining depth.
hash_table	Hash Table to use.

Returns

An evaluated score, as a disc difference.

PVS_midgame()

int PVS_midgame	(	Search *	search,
		const int	alpha,
		const int	beta,
		int	depth,
		Node *	parent
	)

Evaluate a position with a deep Principal Variation Search algorithm.

This function is used when there are still many empty squares on the board. Move ordering, hash table cutoff, enhanced transposition cutoff, etc. are used in order to diminish the size of the tree to analyse, but at the expense of a slower speed.

Parameters

search	Search.
alpha	Lower bound.
beta	Upper bound.
depth	Depth.
parent	Parent node.

Returns

A score, as a disc difference.

PVS_shallow()

int PVS_shallow	(	Search *	search,
		int	alpha,
		int	beta,
		int	depth
	)

Evaluate a midgame position at shallow depth.

This function is used when there are still many empty squares on the board. Move ordering, hash table cutoff, enhanced transposition cutoff, etc. are used in order to diminish the size of the tree to analyse, but at the expense of a slower speed.

Parameters

search	Search.
alpha	Alpha bound.
beta	Beta bound.
depth	Search depth.

Returns

An evaluated score, as a disc difference.

search_eval_0()

int search_eval_0

(

Search *

search

)

evaluate a midgame position with the evaluation function.

Parameters

search

Position to evaluate.

search_eval_1()

int search_eval_1	(	Search *	search,
		const int	alpha,
		int	beta
	)

Evaluate a position at depth 1.

As an optimization, the last move is used to only updates the evaluation features.

Parameters

search	Position to evaluate.
alpha	Alpha bound.
beta	Beta bound.

search_eval_2()

int search_eval_2	(	Search *	search,
		int	alpha,
		const int	beta
	)

Evaluate a position at depth 2.

Simple alpha-beta with no move sorting.

Parameters

search	Position to evaluate.
alpha	Lower bound
beta	Upper bound

search_probcut()

static bool search_probcut ( Search *  search, const int  alpha, const int  depth, Node *  parent, int *  value  )

static

Probcut.

Check if a position is worth to analyze further.

Parameters

search	Position to test.
alpha	Alpha lower bound.
depth	Search depth.
parent	Parent node.
value	Returned value.

Returns

true if probable cutoff has been found, false otherwise.

search_restore_probcut()

static void search_restore_probcut ( Search *  search, const NodeType  node_type, const int  selectivity  )

inlinestatic

search_update_probcut()

static void search_update_probcut ( Search *  search, const NodeType  node_type  )

inlinestatic