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#include "fen.hpp"
#include "board.hpp"
#include <cassert>
#include <cctype>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <print>
#include <string>
#include <sys/types.h>
bool WHITE = true;
bool BLACK = false;
static void updateBitboards(Game *g) {
g->PieceBitboard = 0;
g->WhitePieceBitboard = 0;
g->BlackPieceBitboard = 0;
std::memset(g->PieceBitboards, 0, sizeof(g->PieceBitboards));
for (uint8_t i = 0; i < 64; i++) {
Piece piece = g->pieces[i];
if (piece.type == NONEPIECE) {
continue;
}
g->PieceBitboards[piece.color][piece.type] |= (1ULL << i);
if (piece.color) {
g->WhitePieceBitboard |= (1ULL << i);
} else {
g->BlackPieceBitboard |= (1ULL << i);
}
}
g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
}
static void SetPiece(int i, PieceType type, bool color, Game *g) {
if (i < 0 || i >= 64) {
std::println("Fatal: piece outside board");
assert(false && "Malformed board");
exit(1);
}
g->pieces[i] = {.color = color, .type = type};
}
static void clearBoard(Game *g) {
for (auto &piece : g->pieces) {
piece = {.color = false, .type = NONEPIECE};
}
g->blackCastleKing = false;
g->blackCastleQueen = false;
g->whiteCastleKing = false;
g->whiteCastleQueen = false;
}
enum parserState : std::uint8_t {
BOARD,
PLAYER_TO_MOVE,
CASTLE,
ENPASSANT,
HALF_MOVE_CLOCK,
FULL_MOVE_CLOCK,
};
void setBoardFen(const std::string &fen, Game *g) {
clearBoard(g);
// example fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
int file = 0;
int rank = 7;
Position enpassant = {};
parserState parser_state = BOARD;
for (uint i = 0; i < fen.length(); i++) {
char c = fen[i];
if (c == ' ') {
if (parser_state == BOARD) {
parser_state = PLAYER_TO_MOVE;
continue;
}
if (parser_state == PLAYER_TO_MOVE) {
parser_state = CASTLE;
continue;
}
if (parser_state == CASTLE) {
parser_state = ENPASSANT;
continue;
}
if (parser_state == ENPASSANT) {
parser_state = HALF_MOVE_CLOCK;
continue;
}
if (parser_state == HALF_MOVE_CLOCK) {
parser_state = FULL_MOVE_CLOCK;
continue;
}
}
if (parser_state == ENPASSANT) {
continue;
}
if (parser_state == CASTLE) {
if (c == '-') {
g->blackCastleKing = false;
g->blackCastleQueen = false;
g->whiteCastleKing = false;
g->whiteCastleQueen = false;
continue;
}
if (c == 'K') {
g->whiteCastleKing = true;
continue;
}
if (c == 'Q') {
g->whiteCastleQueen = true;
continue;
}
if (c == 'k') {
g->blackCastleKing = true;
continue;
}
if (c == 'q') {
g->blackCastleQueen = true;
continue;
}
}
if (parser_state == PLAYER_TO_MOVE) {
if (toupper(c) == 'W') {
g->turn = WHITE;
continue;
}
if (toupper(c) == 'B') {
g->turn = BLACK;
continue;
}
}
if (parser_state == BOARD) {
if (isdigit(c) != 0) {
int move = c - '0';
file += move;
if (file > 8) {
std::println("Fatal: file was to big");
assert(false && "Malformed file");
exit(1);
return; // malformed file
}
continue;
}
if (c == '/') {
file = 0;
rank--;
if (rank < 0) {
std::println("Fatal: rank was to big");
assert(false && "Malformed rank");
exit(1);
return; // malformed rank
}
continue;
};
if (toupper(c) == 'N') {
SetPiece((rank * 8) + file, KNIGHT, isupper(c) != 0, g);
file++;
continue;
};
if (toupper(c) == 'R') {
SetPiece((rank * 8) + file, ROOK, isupper(c) != 0, g);
file++;
continue;
}
if (toupper(c) == 'Q') {
SetPiece((rank * 8) + file, QUEEN, isupper(c) != 0, g);
file++;
continue;
}
if (toupper(c) == 'B') {
SetPiece((rank * 8) + file, BISHOP, isupper(c) != 0, g);
file++;
continue;
}
if (toupper(c) == 'P') {
SetPiece((rank * 8) + file, PAWN, isupper(c) != 0, g);
file++;
continue;
}
if (toupper(c) == 'K') {
SetPiece((rank * 8) + file, KING, isupper(c) != 0, g);
file++;
continue;
}
}
break;
}
g->enPassant = enpassant;
updateBitboards(g);
int whiteKingCount = __builtin_popcountll(g->PieceBitboards[true][KING]);
int blackKingCount = __builtin_popcountll(g->PieceBitboards[false][KING]);
if (whiteKingCount != 1) {
std::cerr << "ERROR: expected exactly one white king\n";
exit(1);
}
if (blackKingCount != 1) {
std::cerr << "ERROR: expected exactly one black king\n";
exit(1);
}
}
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