Winglet

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Winglet,
a didactic open source chess engines by Stef Luijten written in C++, licensed under the GNU General Public License. The development of Winglet was documented on the website tutorial Winglet, Writing a Chess Program in 99 Steps, started in 2011, now hosted by the Wayback Machine [1]. Winglet is intended as bitboard version of TSCP with WinBoard support [2], and is loosely derived from Wing, Stef Luijten's former private engine [3], in the meantime also open source [4].
Winglet [5]

Description

Board Representation

Winglet applies a mixture of Kindergarten Bitboards and Magic Bitboards [6] to determine sliding piece attacks with 32 KiB precalculated lookup tables[64][64] each on ranks, files, diagonals and anti-diagonals, indexed by square and hashed line occupancy - the inner six bits multiplied by a magic factor and shifted right by the strange looking 57, while 58 is more natural to ensure a six bit index range, using a constant factor (b-File) for all squares of a diagonal or anti-diagonal, ...
U64 arrDiagonalAttacks[64][64]] /* requires initialization */
 
U64 diagonalKindergartenAttacks(U64 occ, enumSquare sq) {
   occ = (diagonalMaskEx[sq] & occ) * C64(0x0202020202020202) >> 58;
   return arrDiagonalAttacks[sq][occ];
}
... but "magic" Winglet factors are designed such that the most significant bit of the 64-bit product will always be clear, that is positive if interpreted as signed 64-bit integer. It seems, Winglet's occupied index calculations emulate Wing's rotated bitboard indices for same attack table layout:
/*                 Winglet's occupancy state             ==            Wing's occupancy state */
(occ & MG_DIAGA8H1MASK[sq]) * MG_DIAGA8H1MAGIC[sq] >> 57 == (occ045 >> DIAGA8H1_ATTACK_SHIFT[sq]) & 63
(occ & MG_DIAGA1H8MASK[sq]) * MG_DIAGA1H8MAGIC[sq] >> 57 == (occ315 >> DIAGA1H8_ATTACK_SHIFT[sq]) & 63
(occ & MG_FILEMASK[sq])     * MG_FILEMAGIC[sq])    >> 57 == (occ090 >> FILE_ATTACK_SHIFT[sq])     & 63

Search


Evaluation


See also


Postings


External Links

Chess Engine

Tutorial Archive


Misc


References

  1. ^ Winglet, Writing a Chess Program in 99 Steps by Stef Luijten, hosted by the Wayback Machine
  2. ^ Writing a chess program in xx steps by Stef Luijten, CCC, April 18, 2011
  3. ^ Winglet, Writing a Chess Program in 99 Steps by Stef Luijten, hosted by the Wayback Machine
  4. ^ Index of /chess/engines/Jim Ablett/WING by Jim Ablett, hosted by Kirill Kryukov
  5. ^ Winglet with attached tufts of an KC-135A during NASA Winglet stu dy 1979. The tufts are needed to measure the airflow, Winglet from Wingtip device - Wikipedia, KC-135 EC79-11481: KC-135A in flight - closeup of winglet with attached tufts, August 20, 1979
  6. ^ Writing a chess program in 99 steps - Move generation for sliding pieces by Stef Luijten, Wayback Machine
  7. ^ Chesser: A Chess Engine derived from wingletx by Syed Fahad, CCC, December 24, 2014
  8. ^ ucarion/godot · GitHub
  9. ^ kenshinthebattosai/Kenny · GitHub
  10. ^ New Winboard Engine 'Kenny' - JA builds available by Jim Ablett, CCC, January 08, 2013
  11. ^ Re: where to start chess programming? by Marco Belli, CCC, June 22, 2014
  12. ^ PortugalTheMan/winglet · GitHub
  13. ^ Winglet Chess Engine; Revived! by PortugalTheMan, Chess.com, Septermber 24, 2014
  14. ^ copy was taken in ‎March ‎07, ‎2013, images and archives included

What links here?

Page Date Edited
Abdullah Al-Ghaznawi Apr 25, 2015
Engines Mar 10, 2018
Godot Apr 28, 2015
Hakkapeliitta Apr 26, 2016
Kindergarten Bitboards Aug 1, 2017
Little Wing Oct 26, 2017
Marco Belli Jan 6, 2018
Recommended Reading Nov 17, 2017
Stef Luijten Apr 26, 2015
Vajolet Jan 25, 2018
Wing Oct 26, 2017
Winglet Apr 26, 2015

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