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Code Issues Releases Wiki Activity

Simplify from_fen()

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No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-01-14 09:20:23 +01:00
parent 62cd133b3a
commit b85bcc039c
1 changed files with 17 additions and 27 deletions
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44
src/position.cpp
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@ -181,7 +181,7 @@ void Position::from_fen(const string& fen, bool c960) {
A FEN string contains six fields. The separator between fields is a space. The fields are:
1) Piece placement (from white's perspective). Each rank is described, starting with rank 8 and ending
with rank 1; within each rank, the contents of each square are described from file a through file h.
with rank 1; within each rank, the contents of each square are described from file A through file H.
Following the Standard Algebraic Notation (SAN), each piece is identified by a single letter taken
from the standard English names. White pieces are designated using upper-case letters ("PNBRQK")
while Black take lowercase ("pnbrqk"). Blank squares are noted using digits 1 through 8 (the number
@ -206,31 +206,24 @@ void Position::from_fen(const string& fen, bool c960) {
char token;
int hmc, fmn;
std::istringstream ss(fen);
Rank rank = RANK_8;
File file = FILE_A;
Square sq = SQ_A8;
clear();
// 1. Piece placement field
while (ss.get(token) && token != ' ')
{
if (isdigit(token))
if (pieceLetters.find(token) != pieceLetters.end())
{
file += File(token - '0'); // Skip the given number of files
continue;
put_piece(pieceLetters[token], sq);
sq++;
}
else if (isdigit(token))
sq += Square(token - '0'); // Skip the given number of files
else if (token == '/')
{
file = FILE_A;
rank--;
continue;
}
if (pieceLetters.find(token) == pieceLetters.end())
sq -= SQ_A3; // Jump back of 2 rows
else
goto incorrect_fen;
put_piece(pieceLetters[token], make_square(file, rank));
file++;
}
// 2. Active color
@ -244,24 +237,20 @@ void Position::from_fen(const string& fen, bool c960) {
// 3. Castling availability
while (ss.get(token) && token != ' ')
{
if (token == '-')
continue;
if (!set_castling_rights(token))
goto incorrect_fen;
}
// 4. En passant square -- ignore if no capture is possible
// 4. En passant square
char col, row;
if ( (ss.get(col) && (col >= 'a' && col <= 'h'))
&& (ss.get(row) && (row == '3' || row == '6')))
{
Square fenEpSquare = make_square(file_from_char(col), rank_from_char(row));
Color them = opposite_color(sideToMove);
st->epSquare = make_square(file_from_char(col), rank_from_char(row));
if (attacks_from<PAWN>(fenEpSquare, them) & pieces(PAWN, sideToMove))
st->epSquare = fenEpSquare;
// Ignore if no capture is possible
Color them = opposite_color(sideToMove);
if (!(attacks_from<PAWN>(st->epSquare, them) & pieces(PAWN, sideToMove)))
st->epSquare = SQ_NONE;
}
// 5. Halfmove clock
@ -347,7 +336,8 @@ bool Position::set_castling_rights(char token) {
initialKRFile = rookFile;
}
}
else return false;
else
return token == '-';
return true;
}