Material and home-pawn signatures used by database search prefilters. More...

#include "scid/core/board.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <string>
#include <utility>

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Namespaces
namespace	scid
	Public namespace for libscid.

namespace	scid::database
	Database sessions, metadata, names, filters, trees and storage.

Macros
#define	MATSIG_FlipColor(x) ((x) >> 12) \| (((x) & 0x00000FFF) << 12)
	Returns `x` with White and Black material fields exchanged.

#define	MATSIG_Has_WQ(x) ((x) & MASK_WQ)
	Returns non-zero when `x` contains at least one White queen.

#define	MATSIG_Has_BQ(x) ((x) & MASK_BQ)
	Returns non-zero when `x` contains at least one Black queen.

#define	MATSIG_Has_WR(x) ((x) & MASK_WR)
	Returns non-zero when `x` contains at least one White rook.

#define	MATSIG_Has_BR(x) ((x) & MASK_BR)
	Returns non-zero when `x` contains at least one Black rook.

#define	MATSIG_Has_WB(x) ((x) & MASK_WB)
	Returns non-zero when `x` contains at least one White bishop.

#define	MATSIG_Has_BB(x) ((x) & MASK_BB)
	Returns non-zero when `x` contains at least one Black bishop.

#define	MATSIG_Has_WN(x) ((x) & MASK_WN)
	Returns non-zero when `x` contains at least one White knight.

#define	MATSIG_Has_BN(x) ((x) & MASK_BN)
	Returns non-zero when `x` contains at least one Black knight.

#define	MATSIG_Has_WP(x) ((x) & MASK_WP)
	Returns non-zero when `x` contains at least one White pawn.

#define	MATSIG_Has_BP(x) ((x) & MASK_BP)
	Returns non-zero when `x` contains at least one Black pawn.

#define	MATSIG_HasQueens(x) ((x) & (MASK_WQ \| MASK_BQ))
	Returns non-zero when either side has a queen.

#define	MATSIG_HasRooks(x) ((x) & (MASK_WR \| MASK_BR))
	Returns non-zero when either side has a rook.

#define	MATSIG_HasBishops(x) ((x) & (MASK_WB \| MASK_BB))
	Returns non-zero when either side has a bishop.

#define	MATSIG_HasKnights(x) ((x) & (MASK_WN \| MASK_BN))
	Returns non-zero when either side has a knight.

#define	MATSIG_HasPawns(x) ((x) & (MASK_WP \| MASK_BP))
	Returns non-zero when either side has a pawn.

#define	MATSIG_Count_WQ(x) (((x) & MASK_WQ) >> SHIFT_WQ)
	Returns the White queen count from `x`.

#define	MATSIG_Count_BQ(x) (((x) & MASK_BQ) >> SHIFT_BQ)
	Returns the Black queen count from `x`.

#define	MATSIG_Count_WR(x) (((x) & MASK_WR) >> SHIFT_WR)
	Returns the White rook count from `x`.

#define	MATSIG_Count_BR(x) (((x) & MASK_BR) >> SHIFT_BR)
	Returns the Black rook count from `x`.

#define	MATSIG_Count_WB(x) (((x) & MASK_WB) >> SHIFT_WB)
	Returns the White bishop count from `x`.

#define	MATSIG_Count_BB(x) (((x) & MASK_BB) >> SHIFT_BB)
	Returns the Black bishop count from `x`.

#define	MATSIG_Count_WN(x) (((x) & MASK_WN) >> SHIFT_WN)
	Returns the White knight count from `x`.

#define	MATSIG_Count_BN(x) (((x) & MASK_BN) >> SHIFT_BN)
	Returns the Black knight count from `x`.

#define	MATSIG_Count_WP(x) (((x) & MASK_WP) >> SHIFT_WP)
	Returns the White pawn count from `x`.

#define	MATSIG_Count_BP(x) (((x) & MASK_BP) >> SHIFT_BP)
	Returns the Black pawn count from `x`.

Material Signature Layout
From high to low bits, the layout is: bits 22-23: White queens bits 20-21: White rooks bits 18-19: White bishops bits 16-17: White knights bits 12-15: White pawns bits 10-11: Black queens bits 08-09: Black rooks bits 06-07: Black bishops bits 04-05: Black knights bits 00-03: Black pawns Pawns can represent ordinary counts from zero to eight. Other piece counts are saturated at three when signatures are made from a position.
#define	SHIFT_BP 0

#define	SHIFT_BN 4

#define	SHIFT_BB 6

#define	SHIFT_BR 8

#define	SHIFT_BQ 10

#define	SHIFT_WP 12

#define	SHIFT_WN 16

#define	SHIFT_WB 18

#define	SHIFT_WR 20

#define	SHIFT_WQ 22

#define	MASK_BP 0x0000000F
	Mask for black pawns.

#define	MASK_BN 0x00000030
	Mask for black knights.

#define	MASK_BB 0x000000C0
	Mask for black bishops.

#define	MASK_BR 0x00000300
	Mask for black rooks.

#define	MASK_BQ 0x00000C00
	Mask for black queens.

#define	MASK_WP 0x0000F000
	Mask for white pawns.

#define	MASK_WN 0x00030000
	Mask for white knights.

#define	MASK_WB 0x000C0000
	Mask for white bishops.

#define	MASK_WR 0x00300000
	Mask for white rooks.

#define	MASK_WQ 0x00C00000
	Mask for white queens.

Typedefs
typedef std::uint32_t	scid::database::matSigT
	Compact material signature used for fast database search prefilters.

Functions
scid::core::uint	scid::database::matsig_getCount (matSigT m, scid::core::pieceT p)
	Returns the count of piece `p` stored in material signature `m`.

matSigT	scid::database::matsig_setCount (matSigT m, scid::core::pieceT p, scid::core::uint count)
	Returns `m` with the count for piece `p` replaced by `count`.

std::string	scid::database::matsig_makeString (matSigT matsig)
	Returns a compact textual representation of `matsig`.

bool	scid::database::matsig_isReachable (matSigT mStart, matSigT mTarget, bool promos, bool upromo)
	Returns true when `mStart` could legally decay into `mTarget`.

bool	scid::database::matsig_isReachablePawns (matSigT mStart, matSigT mTarget)
	Returns true when `mStart` could decay into `mTarget` considering pawns only.

matSigT	scid::database::matsig_Make (const scid::core::byte *materialCounts)
	Builds a material signature from a scid::core::Position material array.

bool	scid::database::hpSig_PossibleMatch (scid::core::uint hpSig, const scid::core::byte *changeList)
	Returns true when a game's home-pawn change list could reach `hpSig`.

bool	scid::database::hpSig_Prefix (const scid::core::byte changeListA, const scid::core::byte changeListB)
	Returns true when either home-pawn change list is a prefix of the other.

scid::core::uint	scid::database::hpSig_Final (const scid::core::byte *changeList)
	Returns the final home-pawn signature reached after applying `changeList`.

scid::core::uint	scid::database::hpSig_AddPawn (scid::core::uint hpSig, scid::core::colorT color, scid::core::fyleT fyle)
	Returns `hpSig` with the home-pawn bit for `color` and `fyle` set.

scid::core::uint	scid::database::hpSig_ClearPawn (scid::core::uint hpSig, scid::core::colorT color, scid::core::fyleT fyle)
	Returns `hpSig` with the home-pawn bit for `color` and `fyle` cleared.

std::pair< std::uint16_t, std::uint16_t >	scid::database::hpSig_make (const scid::core::pieceT *board)
	Creates a 16-bit bitmap of the pawns missing from their home ranks.

bool	scid::database::hpSig_match (int hpSig, int nMoved, const scid::core::byte *changeList)
	Returns true when `changeList` can explain the requested missing-pawn bitmap and moved-pawn count.

Variables
const matSigT	scid::database::MASK_BY_PIECE [16]
	Piece-code indexed masks for extracting or replacing a count.

const scid::core::uint	scid::database::SHIFT_BY_PIECE [16]
	Piece-code indexed bit shifts for extracting or replacing a count.

const matSigT	scid::database::MATSIG_Empty = 0
	Material signature for an empty board.

const matSigT	scid::database::MATSIG_StdStart
	Material signature for the standard chess starting position.

const scid::core::uint	scid::database::HPSIG_Empty = 0x0
	Home-pawn signature with no pawns still on their original home squares.

const scid::core::uint	scid::database::HPSIG_StdStart = 0xFFFF
	Home-pawn signature for the starting position.

Detailed Description

Material and home-pawn signatures used by database search prefilters.

These signatures are deliberately lossy. They let the database reject impossible candidate games before decoding movetext, but they do not prove that a game contains a searched position. Material signatures answer "could these piece counts still be present?", while home-pawn signatures answer "could these original pawns have moved?". The exact board search still has to decode candidate games that pass these cheap tests.

Namespaces

Macros

Typedefs

Functions

Variables

Detailed Description