ref: 67d3ac8d4a497a6b51d11b5848f964797fd098b8
dir: /chess.c/
/* moonfish is licensed under the AGPL (v3 or later) */
/* copyright 2023, 2024 zamfofex */
#include <string.h>
#include "moonfish.h"
static void moonfish_force_promotion(struct moonfish_chess *chess, struct moonfish_move **moves, int from, int to, int promotion)
{
(*moves)->from = from;
(*moves)->to = to;
(*moves)->chess = *chess;
(*moves)->chess.board[to] = promotion;
(*moves)->chess.board[from] = moonfish_empty;
(*moves)->chess.passing = 0;
(*moves)->chess.white ^= 1;
if (from == 21 || to == 21) (*moves)->chess.ooo[0] = 0;
if (from == 28 || to == 28) (*moves)->chess.oo[0] = 0;
if (from == 91 || to == 91) (*moves)->chess.ooo[1] = 0;
if (from == 98 || to == 98) (*moves)->chess.oo[1] = 0;
(*moves)++;
}
static void moonfish_force_move(struct moonfish_chess *chess, struct moonfish_move **moves, int from, int to)
{
moonfish_force_promotion(chess, moves, from, to, chess->board[from]);
}
static void moonfish_deltas(struct moonfish_chess *chess, struct moonfish_move **moves, int from, int *deltas, int count, int n)
{
int i;
int to;
while (*deltas) {
to = from;
for (i = 0 ; i < count ; i++) {
to += *deltas * n;
if (chess->board[to] == moonfish_outside) break;
if (chess->board[to] / 16 == chess->board[from] / 16) break;
moonfish_force_move(chess, moves, from, to);
if (chess->board[to] != moonfish_empty) break;
}
deltas++;
}
}
int moonfish_moves(struct moonfish_chess *chess, struct moonfish_move *moves, int from);
int moonfish_validate(struct moonfish_chess *chess)
{
int x, y;
struct moonfish_move moves[32];
int i, count;
for (y = 0 ; y < 8 ; y++) {
for (x = 0 ; x < 8 ; x++) {
count = moonfish_moves(chess, moves, (x + 1) + (y + 2) * 10);
for (i = 0 ; i < count ; i++) {
if (chess->board[moves[i].to] % 16 == moonfish_king) return 0;
}
}
}
return 1;
}
int moonfish_check(struct moonfish_chess *chess)
{
struct moonfish_chess other;
other = *chess;
other.passing = 0;
other.oo[0] = 0;
other.oo[1] = 0;
other.ooo[0] = 0;
other.ooo[1] = 0;
other.white ^= 1;
return moonfish_validate(&other) ^ 1;
}
static int moonfish_attacked(struct moonfish_chess *chess, int from, int to)
{
int piece;
struct moonfish_chess other;
if (chess->white) piece = moonfish_white_king;
else piece = moonfish_black_king;
other = *chess;
other.board[from] = moonfish_empty;
other.board[to] = piece;
return moonfish_check(&other);
}
static void moonfish_castle_low(struct moonfish_chess *chess, struct moonfish_move **moves, int from)
{
int to;
if (!chess->ooo[1 - chess->white]) return;
to = from - 3;
while (to != from) {
if (chess->board[to++] != moonfish_empty) return;
}
if (moonfish_check(chess)) return;
if (moonfish_attacked(chess, from, from - 1)) return;
if (moonfish_attacked(chess, from, from - 2)) return;
moonfish_force_move(chess, moves, from - 4, from - 1);
(*moves)--;
(*moves)->chess.white = chess->white;
moonfish_force_move(&(*moves)->chess, moves, from, from - 2);
}
static void moonfish_castle_high(struct moonfish_chess *chess, struct moonfish_move **moves, int from)
{
int to;
if (!chess->oo[1 - chess->white]) return;
to = from + 2;
while (to != from) {
if (chess->board[to--] != moonfish_empty) return;
}
if (moonfish_check(chess)) return;
if (moonfish_attacked(chess, from, from + 1)) return;
if (moonfish_attacked(chess, from, from + 2)) return;
moonfish_force_move(chess, moves, from + 3, from + 1);
(*moves)--;
(*moves)->chess.white = chess->white;
moonfish_force_move(&(*moves)->chess, moves, from, from + 2);
}
static void moonfish_pawn_moves(struct moonfish_chess *chess, struct moonfish_move **moves, int from, int to)
{
int color;
if (to > 30 && to < 90) {
moonfish_force_move(chess, moves, from, to);
return;
}
color = chess->board[from] & 0xF0;
moonfish_force_promotion(chess, moves, from, to, color | moonfish_queen);
moonfish_force_promotion(chess, moves, from, to, color | moonfish_rook);
moonfish_force_promotion(chess, moves, from, to, color | moonfish_bishop);
moonfish_force_promotion(chess, moves, from, to, color | moonfish_knight);
}
static void moonfish_pawn_capture(struct moonfish_chess *chess, struct moonfish_move **moves, int from, int to)
{
int dy;
if (to == chess->passing) {
dy = chess->white ? 10 : -10;
moonfish_force_move(chess, moves, from, to);
(*moves)[-1].chess.board[to - dy] = moonfish_empty;
return;
}
if (chess->board[to] / 16 != chess->board[from] / 16 && chess->board[to] != moonfish_empty && chess->board[to] != moonfish_outside) {
moonfish_pawn_moves(chess, moves, from, to);
}
}
static void moonfish_move_pawn(struct moonfish_chess *chess, struct moonfish_move **moves, int from)
{
int dy;
dy = chess->white ? 10 : -10;
if (chess->board[from + dy] == moonfish_empty) {
moonfish_pawn_moves(chess, moves, from, from + dy);
if ((chess->white ? from < 40 : from > 80) && chess->board[from + dy * 2] == moonfish_empty) {
moonfish_force_move(chess, moves, from, from + dy * 2);
(*moves)[-1].chess.passing = from + dy;
}
}
moonfish_pawn_capture(chess, moves, from, from + dy + 1);
moonfish_pawn_capture(chess, moves, from, from + dy - 1);
}
int moonfish_moves(struct moonfish_chess *chess, struct moonfish_move *moves, int from)
{
static int steps[] = {0, 1, 8, 8, 8, 1};
static int deltas[][5] = {
{0},
{21, 19, 12, 8, 0},
{11, 9, 0},
{10, 1, 0},
{10, 1, 11, 9, 0},
{10, 1, 11, 9, 0},
};
struct moonfish_move *moves0;
int piece;
int i, count;
moves0 = moves;
piece = chess->board[from];
if (chess->white ? piece / 16 != 1 : piece / 16 != 2) return 0;
moonfish_deltas(chess, &moves, from, deltas[piece % 16 - 1], steps[piece % 16 - 1], 1);
moonfish_deltas(chess, &moves, from, deltas[piece % 16 - 1], steps[piece % 16 - 1], -1);
if (piece % 16 == moonfish_pawn) moonfish_move_pawn(chess, &moves, from);
if (piece % 16 == moonfish_king) {
moonfish_castle_high(chess, &moves, from);
moonfish_castle_low(chess, &moves, from);
count = moves - moves0;
for (i = 0 ; i < count ; i++) {
moves0[i].chess.oo[chess->white ^ 1] = 0;
moves0[i].chess.ooo[chess->white ^ 1] = 0;
}
}
return moves - moves0;
}
void moonfish_chess(struct moonfish_chess *chess)
{
static int pieces[] = {moonfish_rook, moonfish_knight, moonfish_bishop, moonfish_queen, moonfish_king, moonfish_bishop, moonfish_knight, moonfish_rook};
int x, y;
chess->white = 1;
chess->oo[0] = 1;
chess->oo[1] = 1;
chess->ooo[0] = 1;
chess->ooo[1] = 1;
chess->passing = 0;
for (y = 0 ; y < 12 ; y++) {
for (x = 0 ; x < 10 ; x++) {
chess->board[x + y * 10] = moonfish_outside;
}
}
for (x = 0 ; x < 8 ; x++) {
chess->board[x + 21] = pieces[x] | 0x10;
chess->board[x + 91] = pieces[x] | 0x20;
chess->board[x + 31] = moonfish_white_pawn;
chess->board[x + 81] = moonfish_black_pawn;
for (y = 4 ; y < 8 ; y++) chess->board[(x + 1) + y * 10] = moonfish_empty;
}
}
int moonfish_from_uci(struct moonfish_chess *chess, struct moonfish_move *move, char *name)
{
int x0, y0, x1, y1;
int type;
int from, to;
int i, count;
struct moonfish_move moves[32];
if (name[0] < 'a' || name[0] > 'h') return 1;
if (name[1] < '1' || name[1] > '8') return 1;
if (name[2] < 'a' || name[2] > 'h') return 1;
if (name[3] < '1' || name[3] > '8') return 1;
x0 = name[0] - 'a';
y0 = name[1] - '1';
x1 = name[2] - 'a';
y1 = name[3] - '1';
type = moonfish_empty;
if (name[4] == 0) type = chess->board[(x0 + 1) + (y0 + 2) * 10] % 16;
if (name[4] == 'q') type = moonfish_queen;
if (name[4] == 'r') type = moonfish_rook;
if (name[4] == 'b') type = moonfish_bishop;
if (name[4] == 'n') type = moonfish_knight;
if (type == moonfish_empty) return 1;
if (type == moonfish_king && x0 == 4) {
if (x1 == 0) x1 = 2;
if (x1 == 7) x1 = 6;
}
from = (x0 + 1) + (y0 + 2) * 10;
to = (x1 + 1) + (y1 + 2) * 10;
count = moonfish_moves(chess, moves, from);
for (i = 0 ; i < count ; i++) {
if (moves[i].to != to) continue;
if (moves[i].chess.board[to] % 16 != type) continue;
*move = moves[i];
return 0;
}
return 1;
}
void moonfish_to_uci(struct moonfish_chess *chess, struct moonfish_move *move, char *name)
{
int x, y;
int piece;
x = move->from % 10 - 1;
y = move->from / 10 - 2;
name[0] = x + 'a';
name[1] = y + '1';
x = move->to % 10 - 1;
y = move->to / 10 - 2;
name[2] = x + 'a';
name[3] = y + '1';
name[4] = 0;
piece = move->chess.board[move->to];
if (piece != chess->board[move->from]) {
if (piece % 16 == moonfish_queen) name[4] = 'q';
if (piece % 16 == moonfish_rook) name[4] = 'r';
if (piece % 16 == moonfish_bishop) name[4] = 'b';
if (piece % 16 == moonfish_knight) name[4] = 'n';
name[5] = 0;
}
}
int moonfish_finished(struct moonfish_chess *chess)
{
struct moonfish_move moves[32];
int x, y;
int i, count;
for (y = 0 ; y < 8 ; y++) {
for (x = 0 ; x < 8 ; x++) {
count = moonfish_moves(chess, moves, (x + 1) + (y + 2) * 10);
for (i = 0 ; i < count ; i++) {
if (moonfish_validate(&moves[i].chess)) return 0;
}
}
}
return 1;
}
int moonfish_equal(struct moonfish_chess *a, struct moonfish_chess *b)
{
int x, y, i;
if (a->white != b->white) return 0;
if (a->passing != b->passing) return 0;
if (a->oo[0] != b->oo[0]) return 0;
if (a->oo[1] != b->oo[1]) return 0;
if (a->ooo[0] != b->ooo[0]) return 0;
if (a->ooo[1] != b->ooo[1]) return 0;
for (y = 0 ; y < 8 ; y++) {
for (x = 0 ; x < 8 ; x++) {
i = (x + 1) + (y + 2) * 10;
if (a->board[i] != b->board[i]) {
return 0;
}
}
}
return 1;
}
#ifndef moonfish_mini
int moonfish_move(struct moonfish_chess *chess, struct moonfish_move *found, int from, int to)
{
struct moonfish_move moves[32];
int i, count;
count = moonfish_moves(chess, moves, from);
for (i = 0 ; i < count ; i++) {
if (moves[i].to == to && moonfish_validate(&moves[i].chess)) {
*found = moves[i];
return 0;
}
}
return 1;
}
int moonfish_from_fen(struct moonfish_chess *chess, char *fen)
{
int x, y;
int type, color;
char ch;
for (y = 0 ; y < 8 ; y++) {
for (x = 0 ; x < 8 ; x++) {
chess->board[(x + 1) + (y + 2) * 10] = moonfish_empty;
}
}
x = 0;
y = 0;
chess->white = 1;
chess->oo[0] = 0;
chess->oo[1] = 0;
chess->ooo[0] = 0;
chess->ooo[1] = 0;
chess->passing = 0;
for (;;) {
ch = *fen++;
if (ch == 0) return 0;
if (ch == ' ') break;
if (ch == '/') {
x = 0;
y++;
continue;
}
if (ch >= '0' && ch <= '9') {
x += ch - '0';
continue;
}
color = 0x20;
if (ch >= 'A' && ch <= 'Z') {
ch -= 'A' - 'a';
color = 0x10;
}
type = 0;
if (ch == 'p') type = 1;
if (ch == 'n') type = 2;
if (ch == 'b') type = 3;
if (ch == 'r') type = 4;
if (ch == 'q') type = 5;
if (ch == 'k') type = 6;
chess->board[(x + 1) + (9 - y) * 10] = type | color;
x++;
}
if (*fen++ == 'b') chess->white = 0;
if (*fen++ != ' ') return 0;
for (;;) {
ch = *fen++;
if (ch == 0) return 0;
if (ch == ' ') break;
if (ch == 'K') chess->oo[0] = 1;
if (ch == 'k') chess->oo[1] = 1;
if (ch == 'Q') chess->ooo[0] = 1;
if (ch == 'q') chess->ooo[1] = 1;
if (ch >= 'A' && ch <= 'H') return 1;
if (ch >= 'a' && ch <= 'h') return 1;
}
if (*fen == '-') return 0;
x = *fen++ - 'a';
y = *fen++ - '1';
chess->passing = (x + 1) + (y + 2) * 10;
return 0;
}
int moonfish_checkmate(struct moonfish_chess *chess)
{
if (!moonfish_check(chess)) return 0;
return moonfish_finished(chess);
}
static int moonfish_match_move(struct moonfish_chess *chess, struct moonfish_move *move, int type, int promotion, int x0, int y0, int x1, int y1, int check, int captured)
{
int found;
int x, y;
struct moonfish_move moves[32];
int xi0, yi0, xi1, yi1;
int i, count;
xi0 = 0, xi1 = 8;
yi0 = 0, yi1 = 8;
if (x0) xi0 = x0 - 1, xi1 = x0;
if (y0) yi0 = y0 - 1, yi1 = y0;
found = 0;
for (y = yi0 ; y < yi1 ; y++) {
for (x = xi0 ; x < xi1 ; x++) {
count = moonfish_moves(chess, moves, (x + 1) + (y + 2) * 10);
for (i = 0 ; i < count ; i++) {
if (chess->board[moves[i].from] % 16 != type) continue;
if (promotion && promotion != moves[i].chess.board[moves[i].to] % 16) continue;
if (moves[i].to % 10 != x1) continue;
if (moves[i].to / 10 - 1 != y1) continue;
if (captured) {
if (chess->board[moves[i].from] % 16 == moonfish_pawn) {
if (moves[i].from % 10 == moves[i].to % 10) continue;
}
else {
if (chess->board[moves[i].to] == moonfish_empty) continue;
}
}
if (!moonfish_validate(&moves[i].chess)) continue;
if (check && !moonfish_check(chess)) continue;
if (check == 2 && !moonfish_checkmate(chess)) continue;
if (found) return 1;
found = 1;
*move = moves[i];
}
}
}
if (!found) return 1;
return 0;
}
int moonfish_from_san(struct moonfish_chess *chess, struct moonfish_move *move, char *name)
{
int count;
int type, promotion;
int check, capture;
int x0, y0;
int x1, y1;
char *name0, name_array[32], ch;
size_t length, i;
length = strlen(name);
if (length >= sizeof name_array) return 1;
strcpy(name_array, name);
name = name_array;
/* reverse the string (because it is easier to parse) */
for (i = length / 2 ; i < length ; i++) {
ch = name[i];
name[i] = name[length - i - 1];
name[length - i - 1] = ch;
}
check = 0;
if (*name == '+') check = 1;
if (*name == '#') check = 2;
if (check) name++;
count = 0;
for (name0 = name ; *name0 != 0 ; name0++) {
if (*name0 == '-') continue;
if (*name0 == '_') continue;
if (*name0 == '0') {
count++;
continue;
}
if (*name0 == 'O') {
count++;
continue;
}
if (*name0 == 'o') {
count++;
continue;
}
count = 0;
break;
}
if (count > 0) {
if (chess->white) y1 = 1;
else y1 = 8;
if (count == 2) {
x1 = 7;
}
else {
if (count == 3) x1 = 3;
else return 1;
}
return moonfish_match_move(chess, move, moonfish_king, 0, 5, y1, x1, y1, check, 0);
}
x0 = 0;
y0 = 0;
x1 = 0;
y1 = 0;
check = 0;
switch (*name++) {
default:
promotion = 0;
name--;
break;
case 'K':
case 'k':
promotion = moonfish_king;
break;
case 'Q':
case 'q':
promotion = moonfish_queen;
break;
case 'R':
case 'r':
promotion = moonfish_rook;
break;
case 'B':
case 'b':
promotion = moonfish_bishop;
break;
case 'N':
case 'n':
promotion = moonfish_knight;
break;
}
if (promotion != moonfish_empty && *name == '=') name++;
capture = 0;
if (*name >= '1' && *name <= '8') y1 = *name++ - '0';
if (*name >= 'a' && *name <= 'h') x1 = *name++ - 'a' + 1;
if (*name == 'x') capture = 1, name++;
if (*name >= '1' && *name <= '8') y0 = *name++ - '0';
if (*name >= 'a' && *name <= 'h') x0 = *name++ - 'a' + 1;
if (x1 == 0) return 1;
if (y1 == 0) return 1;
switch (*name++) {
default:
type = moonfish_pawn;
if (x0 && y0) type = chess->board[x0 + (y0 + 1) * 10] % 16;
if (type == 0x0F) return 1;
name--;
break;
case 'K':
case 'k':
type = moonfish_king;
break;
case 'Q':
case 'q':
type = moonfish_queen;
break;
case 'R':
case 'r':
type = moonfish_rook;
break;
case 'B':
type = moonfish_bishop;
break;
case 'N':
case 'n':
type = moonfish_knight;
break;
}
if (*name != 0) return 1;
return moonfish_match_move(chess, move, type, promotion, x0, y0, x1, y1, check, capture);
}
void moonfish_to_fen(struct moonfish_chess *chess, char *fen)
{
int x, y;
int piece;
int count;
for (y = 7 ; y >= 0 ; y--) {
count = 0;
for (x = 0 ; x < 8 ; x++) {
piece = chess->board[(x + 1) + (y + 2) * 10];
if (piece == moonfish_empty) {
count++;
continue;
}
if (count != 0) {
*fen++ = '0' + count;
count = 0;
}
switch (piece % 16) {
default:
return;
case moonfish_pawn:
*fen = 'p';
break;
case moonfish_knight:
*fen = 'n';
break;
case moonfish_bishop:
*fen = 'b';
break;
case moonfish_rook:
*fen = 'r';
break;
case moonfish_queen:
*fen = 'q';
break;
case moonfish_king:
*fen = 'k';
break;
}
if (piece / 16 == 1) *fen += 'A' - 'a';
fen++;
}
if (count != 0) *fen++ = '0' + count;
*fen++ = '/';
}
fen--;
*fen++ = ' ';
if (chess->white) *fen++ = 'w';
else *fen++ = 'b';
*fen++ = ' ';
if (chess->oo[0]) *fen++ = 'K';
if (chess->ooo[0]) *fen++ = 'Q';
if (chess->oo[1]) *fen++ = 'k';
if (chess->ooo[1]) *fen++ = 'q';
if (fen[-1] == ' ') *fen++ = '-';
*fen++ = ' ';
if (chess->passing) {
*fen++ = 'a' + chess->passing % 10 - 1;
*fen++ = '1' + chess->passing / 10 - 2;
}
if (fen[-1] == ' ') *fen++ = '-';
*fen = 0;
}
void moonfish_to_san(struct moonfish_chess *chess, struct moonfish_move *move, char *name, int check)
{
static char names[] = "NBRQK";
int x, y;
struct moonfish_move moves[32];
char file_ambiguity, rank_ambiguity, ambiguity;
int to_x, to_y;
int from_x, from_y;
int i, count;
from_x = move->from % 10 - 1;
from_y = move->from / 10 - 2;
to_x = move->to % 10 - 1;
to_y = move->to / 10 - 2;
if (chess->board[move->from] % 16 == moonfish_king && from_x == 4) {
if (to_x == 2) {
strcpy(name, "O-O-O");
return;
}
if (to_x == 6) {
strcpy(name, "O-O");
return;
}
}
if (chess->board[move->from] % 16 == moonfish_pawn) {
if (from_x != to_x) {
*name++ = from_x + 'a';
*name++ = 'x';
}
*name++ = to_x + 'a';
*name++ = to_y + '1';
if (move->chess.board[move->to] % 16 != moonfish_pawn) {
*name++ = '=';
*name++ = names[move->chess.board[move->to] % 16 - 2];
}
*name = 0;
return;
}
file_ambiguity = 0;
rank_ambiguity = 0;
ambiguity = 0;
for (y = 0 ; y < 8 ; y++) {
for (x = 0 ; x < 8 ; x++) {
if ((x + 1) + (y + 2) * 10 == move->from) continue;
count = moonfish_moves(chess, moves, (x + 1) + (y + 2) * 10);
for (i = 0 ; i < count ; i++) {
if (moves[i].to != move->to) continue;
if (chess->board[moves[i].from] != chess->board[move->from]) continue;
ambiguity = 1;
if (moves[i].from % 10 - 1 == from_x) file_ambiguity = 1;
if (moves[i].from / 10 - 2 == from_y) rank_ambiguity = 1;
}
}
}
*name++ = names[(chess->board[move->from] & 0xF) - 2];
if (ambiguity) {
if (file_ambiguity) {
if (rank_ambiguity) *name++ = from_x + 'a';
*name++ = from_y + '1';
}
else {
*name++ = from_x + 'a';
}
}
if (chess->board[move->to] != moonfish_empty) *name++ = 'x';
*name++ = to_x + 'a';
*name++ = to_y + '1';
if (moonfish_checkmate(&move->chess)) {
if (~check & 1) *name++ = '#';
}
else {
if (moonfish_check(&move->chess)) {
if (~check & 2) *name++ = '+';
}
}
*name = 0;
}
#endif