kate/BadFish
1
0
Fork 0
mirror of https://github.com/sockspls/badfish synced 2025-04-30 16:53:09 +00:00
Code Issues Releases Wiki Activity

Simplify pseudo_legal()

Browse source 
Big simplification of pawn move check.

Code has been tested with a brute force approach: for
every position reached during a bench search, the function
has been called for each combinations of Move(from, to)
and verified the result is the same of old code.

Actually this function is very critical becuase is the
one that ensures corrupted TT moves are discarded, so
to properly test it a simple bench is not enough.

Verified also speed is not changed.

No functional chnage.
This commit is contained in:
Marco Costalba 2014-03-10 08:38:23 +01:00
parent 20ff12e1be
commit d2a8ba3299
1 changed files with 11 additions and 54 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

65
src/position.cpp
View file

@ -38,11 +38,12 @@ static const string PieceToChar(" PNBRQK pnbrqk");
CACHE_LINE_ALIGNMENT
Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
Value PieceValue[PHASE_NB][PIECE_NB] = {
{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
static Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
namespace Zobrist {
Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
@ -530,71 +531,27 @@ bool Position::pseudo_legal(const Move m) const {
// Handle the special case of a pawn move
if (type_of(pc) == PAWN)
{
// Move direction must be compatible with pawn color
int direction = to - from;
if ((us == WHITE) != (direction > 0))
return false;
// We have already handled promotion moves, so destination
// cannot be on the 8th/1st rank.
if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1)
if (rank_of(to) == relative_rank(us, RANK_8))
return false;
// Proceed according to the square delta between the origin and
// destination squares.
switch (direction)
{
case DELTA_NW:
case DELTA_NE:
case DELTA_SW:
case DELTA_SE:
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
return false;
if ( !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
// From and to files must be one file apart, avoids a7h5
if (abs(file_of(from) - file_of(to)) != 1)
return false;
break;
&& !((from + pawn_push(us) == to) && empty(to)) // Not a single push
case DELTA_N:
case DELTA_S:
// Pawn push. The destination square must be empty.
if (!empty(to))
&& !( (from + 2 * pawn_push(us) == to) // Not a double push
&& (rank_of(from) == relative_rank(us, RANK_2))
&& empty(to)
&& empty(to - pawn_push(us))))
return false;
break;
case DELTA_NN:
// Double white pawn push. The destination square must be on the fourth
// rank, and both the destination square and the square between the
// source and destination squares must be empty.
if ( rank_of(to) != RANK_4
|| !empty(to)
|| !empty(from + DELTA_N))
return false;
break;
case DELTA_SS:
// Double black pawn push. The destination square must be on the fifth
// rank, and both the destination square and the square between the
// source and destination squares must be empty.
if ( rank_of(to) != RANK_5
|| !empty(to)
|| !empty(from + DELTA_S))
return false;
break;
default:
return false;
}
}
else if (!(attacks_from(pc, from) & to))
return false;
// Evasions generator already takes care to avoid some kind of illegal moves
// and pl_move_is_legal() relies on this. We therefore have to take care that
// the same kind of moves are filtered out here.
// and legal() relies on this. We therefore have to take care that the same
// kind of moves are filtered out here.
if (checkers())
{
if (type_of(pc) != KING)