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'''[[Main Page|Home]] * [[Engines]] * QBBEngine'''
'''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 on the [[Pedone]] site <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]],
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]].
=Board-Definition=
The [[Bitboard Board-Definition|board-definition]] with vertical [[Nibble|nibbles]] as [[Pieces#PieceCoding|piece or empty square codes]]:
{| class="wikitable"
|-
! rowspan="2" | 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
|}
<pre>
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
</pre>
=See also=
* [[Pedone]]
=External Links=
* [https://sites.google.com/site/pedonechess/a-didactic-engine QBBEngine - a didactic engine]
=References=
<references />
'''[[Engines|Up one Level]]'''
[[Category:Open Source]]
[[Category:UCI]]
[[Category:Didactic]]
'''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 on the [[Pedone]] site <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]],
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]].
=Board-Definition=
The [[Bitboard Board-Definition|board-definition]] with vertical [[Nibble|nibbles]] as [[Pieces#PieceCoding|piece or empty square codes]]:
{| class="wikitable"
|-
! rowspan="2" | 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
|}
<pre>
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
</pre>
=See also=
* [[Pedone]]
=External Links=
* [https://sites.google.com/site/pedonechess/a-didactic-engine QBBEngine - a didactic engine]
=References=
<references />
'''[[Engines|Up one Level]]'''
[[Category:Open Source]]
[[Category:UCI]]
[[Category:Didactic]]
