Difference between revisions of "QBBEngine"
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'''[[Main Page|Home]] * [[Engines]] * QBBEngine''' | '''[[Main Page|Home]] * [[Engines]] * QBBEngine''' | ||
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| + | [[FILE:KTM Quad 990.jpg|border|right|thumb| A KTM Quad 990 ATV <ref>[https://commons.wikimedia.org/wiki/File:KTM_Quad_990_neutral.jpg A KTM Quad 990 ATV], custom-made from E-ATV Eicker Germany, Basevehicle was a KTM Supermotobike, Typ SM 990 with LC8 engine, Image by [https://commons.wikimedia.org/wiki/User:Ritchyblack Stefan Krause], February 20, 2011, [https://en.wikipedia.org/wiki/Wikimedia_Commons Wikimedia Commons]</ref> ]] | ||
'''QBBEngine''',<br/> | '''QBBEngine''',<br/> | ||
| − | a didactic [[UCI]] compliant [[:Category:Open Source|open source chess engine]] by [[Fabio Gobbato]], written in [[C]] and published as single source file | + | a didactic [[UCI]] compliant [[:Category:Open Source|open source chess engine]] by [[Fabio Gobbato]], written in [[C]] and published as single source file along with [[Pedone]], which apparently uses a similar representation <ref>[https://sites.google.com/site/pedonechess/ Pedone Chess Engine]</ref>. |
The QBBEngine demonstrates the use of a compact [[Quad-Bitboards|quad-bitboard]] structure to [[Board Representation|represent the board]], | The QBBEngine demonstrates the use of a compact [[Quad-Bitboards|quad-bitboard]] structure to [[Board Representation|represent the board]], | ||
and further applies [[Alpha-Beta|alpha-beta search]] and an [[Evaluation|evaluation]] based on static values and [[Piece-Square Tables|piece-square tables]] <ref>[https://sites.google.com/site/pedonechess/a-didactic-engine QBBEngine - a didactic engine]</ref>. | and further applies [[Alpha-Beta|alpha-beta search]] and an [[Evaluation|evaluation]] based on static values and [[Piece-Square Tables|piece-square tables]] <ref>[https://sites.google.com/site/pedonechess/a-didactic-engine QBBEngine - a didactic engine]</ref>. | ||
The program performs a color agnostic [[Move Generation|move generation]] by [[Color Flipping|flipping]] the board each time in [[Make Move|make move]]. | The program performs a color agnostic [[Move Generation|move generation]] by [[Color Flipping|flipping]] the board each time in [[Make Move|make move]]. | ||
| − | =Board-Definition= | + | =Board-Definition= |
| − | The [[Bitboard Board-Definition|board-definition]] with vertical [[Nibble|nibbles]] as [[Pieces#PieceCoding|piece or empty square codes]]: | + | ==C Structure== |
| + | <pre> | ||
| + | /* | ||
| + | Board structure definition | ||
| + | |||
| + | PM,P0,P1,P2 are the 4 bitboards that contain the whole board | ||
| + | PM is the bitboard with the side to move pieces | ||
| + | P0,P1 and P2: with these bitboards you can obtain every type of pieces and every pieces combinations. | ||
| + | */ | ||
| + | typedef struct | ||
| + | { | ||
| + | TBB PM; | ||
| + | TBB P0; | ||
| + | TBB P1; | ||
| + | TBB P2; | ||
| + | uint8_t CastleFlags; /* ..sl..SL short long opponent SHORT LONG side to move */ | ||
| + | uint8_t EnPassant; /* enpassant column, =8 if not set */ | ||
| + | uint8_t Count50; /* 50 move rule counter */ | ||
| + | uint8_t Rep; /* 0 if it's not a repetition, 1 if it is */ | ||
| + | uint8_t STM; /* side to move */ | ||
| + | } TBoard; | ||
| + | </pre> | ||
| + | ==Piece Coding== | ||
| + | The [[Bitboard Board-Definition|board-definition]] with vertical [[Nibble|nibbles]] as [[Pieces#PieceCoding|piece or empty square codes]], i.e. the [[Initial Position|initial position]]: | ||
{| class="wikitable" | {| class="wikitable" | ||
|- | |- | ||
Latest revision as of 11:36, 7 September 2020
A KTM Quad 990 ATV [1]
QBBEngine,
a didactic UCI compliant open source chess engine by Fabio Gobbato, written in C and published as single source file along with Pedone, which apparently uses a similar representation [2].
The QBBEngine demonstrates the use of a compact quad-bitboard structure to represent the board,
and further applies alpha-beta search and an evaluation based on static values and piece-square tables [3].
The program performs a color agnostic move generation by flipping the board each time in make move.
Contents
Board-Definition
C Structure
/*
Board structure definition
PM,P0,P1,P2 are the 4 bitboards that contain the whole board
PM is the bitboard with the side to move pieces
P0,P1 and P2: with these bitboards you can obtain every type of pieces and every pieces combinations.
*/
typedef struct
{
TBB PM;
TBB P0;
TBB P1;
TBB P2;
uint8_t CastleFlags; /* ..sl..SL short long opponent SHORT LONG side to move */
uint8_t EnPassant; /* enpassant column, =8 if not set */
uint8_t Count50; /* 50 move rule counter */
uint8_t Rep; /* 0 if it's not a repetition, 1 if it is */
uint8_t STM; /* side to move */
} TBoard;
Piece Coding
The board-definition with vertical nibbles as piece or empty square codes, i.e. the initial position:
| Square | 6 | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 | ~ | 0 | ... | 0 | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 3 | 2 | 1 | 0 | 9 | 8 | 7 | 6 | 5 | ~ | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | ||||||||
| Piece | r | n | b | k | q | b | n | r | p | ~ | P | R | N | B | K | Q | B | N | R | |||||||
| PM | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ~ | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Side to Move | ||||||
| P0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 1 | ~ | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | P | . | B | . | Q | ||
| P1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | ~ | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | N | B | . | K | |||
| P2 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | ~ | 0 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | . | . | R | Q | K |
P2 RQK P1 NB K P0 P B Q PM side to move 1 . . 1 1 . . 1 . 1 1 . 1 1 1 . . . 1 1 . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1 1 1 1 1 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . . 1 1 . . 1 . 1 1 . 1 1 1 . . . 1 1 . 1 . . 1 1 1 1 1 1 1 1
See also
External Links
References
- ↑ A KTM Quad 990 ATV, custom-made from E-ATV Eicker Germany, Basevehicle was a KTM Supermotobike, Typ SM 990 with LC8 engine, Image by Stefan Krause, February 20, 2011, Wikimedia Commons
- ↑ Pedone Chess Engine
- ↑ QBBEngine - a didactic engine
