Clarify the mapping of files to queenside

Author: @nickpelling

We replace in the code the obscure expressions mapping files ABCDEFGH to ABCDDCBA
by an explicite call to an auxiliary function :

  old:   f = min(f, ~f)
  new:   f = map_to_queenside(f)

We used the Golbolt web site (https://godbolt.org) to find the optimal code
for the auxiliary function.

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 30292 W: 6756 L: 6651 D: 16885
http://tests.stockfishchess.org/tests/view/5d8676720ebc5971531d6aa1

No functional change
This commit is contained in:
Stéphane Nicolet
2019-09-23 08:52:27 +02:00
parent 770c8d92f3
commit 7756344d5d
4 changed files with 7 additions and 3 deletions

View File

@@ -119,7 +119,7 @@ void init() {
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
File f = std::min(file_of(s), ~file_of(s));
File f = map_to_queenside(file_of(s));
psq[ pc][ s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)]
: Bonus[pc][rank_of(s)][f]);
psq[~pc][~s] = -psq[pc][s];