static char*
FEN_print_board(const struct position *pos, char *str, enum player turn)
{
int empty_count;
for (int rank = rank_8; ; rank += RSOUTH) {
empty_count = 0;
for (int file = file_a; is_valid_file(file); file += EAST) {
int i = ind(rank, file);
if (turn == black)
i = flip_i(i);
enum piece p = position_piece_at(pos, i);
enum player player = position_player_at(pos, i);
if (p != nonpiece) {
if (empty_count > 0) {
*str++ = '0' + (char)empty_count;
empty_count = 0;
}
if (turn == black)
player = opponent_of(player);
*str++ = square_to_char(p, player);
}
else {
++empty_count;
}
}
if (empty_count > 0)
*str++ = '0' + empty_count;
if (rank == rank_1)
return str;
else
*str++ = '/';
}
}
static void
test_coordinates(void)
{
assert(is_coordinate("g6"));
assert(!is_coordinate("g9"));
assert(!is_coordinate("g0"));
assert(!is_coordinate("6"));
assert(is_coordinate("g6 lorem ipsum"));
assert(!is_coordinate("lorem ipsum"));
assert(str_to_index("g6", white) == ind(rank_6, file_g));
assert(str_to_index("g6", black) == flip_i(ind(rank_6, file_g)));
}