1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
#define MOVES_INTERNAL
#include "engine/moves.h"
#define add_promote_moves(other_flags) \
add_move(moves, from, to, .flags = other_flags | MOVE_PROMOTE_Q); \
add_move(moves, from, to, .flags = other_flags | MOVE_PROMOTE_R); \
add_move(moves, from, to, .flags = other_flags | MOVE_PROMOTE_B); \
add_move(moves, from, to, .flags = other_flags | MOVE_PROMOTE_N)
bitboard_t get_white_pawn_forwardmoves(moves_t* moves, position_t position) {
bitboard_t enemy_bitboard = blacks(position);
bitboard_t friendly_pieces = whites(position);
bitboard_t friendly_pawns = position.bitboards[WHITE_PAWN];
bitboard_t y = friendly_pieces | enemy_bitboard;
bitboard_t x = ~((friendly_pawns << 8) & y) & (friendly_pawns << 8);
bitboard_t first_move_x = x & BITMASK_RANK_3;
first_move_x |= (first_move_x << 8) & (~y);
x |= first_move_x;
return x;
}
bitboard_t get_black_pawn_forwardmoves(moves_t* moves, position_t position) {
bitboard_t enemy_bitboard = whites(position);
bitboard_t friendly_pieces = blacks(position);
bitboard_t friendly_pawns = position.bitboards[BLACK_PAWN];
bitboard_t y = friendly_pieces | enemy_bitboard;
bitboard_t x = ~((friendly_pawns >> 8) & y) & (friendly_pawns >> 8);
bitboard_t first_move_x = x & BITMASK_RANK_6;
first_move_x |= (first_move_x >> 8) & (~y);
x |= first_move_x;
return x;
}
bool pawn_in_range(int to, int next_from, int ub_escape, int turn) {
if (next_from == ub_escape) return false;
if (turn == WHITE_TURN) return to > next_from && to - next_from <= 16;
return to < next_from && next_from - to <= 16;
}
void get_pawn_moves(moves_t* moves, position_t position) {
assert_valid_position(position);
bitboard_t forward_moves;
bitboard_t friendly_pawns;
bitboard_t enemy_bitboard;
if (position.turn == WHITE_TURN) {
forward_moves = get_white_pawn_forwardmoves(moves, position);
friendly_pawns = position.bitboards[WHITE_PAWN];
enemy_bitboard = blacks(position);
} else {
forward_moves = get_black_pawn_forwardmoves(moves, position);
friendly_pawns = position.bitboards[BLACK_PAWN];
enemy_bitboard = whites(position);
}
bitboard_t file_masks[8] = {
BITMASK_FILE_A,
BITMASK_FILE_B,
BITMASK_FILE_C,
BITMASK_FILE_D,
BITMASK_FILE_E,
BITMASK_FILE_F,
BITMASK_FILE_G,
BITMASK_FILE_H,
};
for (int i = 0; i < 8; i++) {
bitboard_t item = file_masks[i] & forward_moves;
bitboard_t pawns = file_masks[i] & friendly_pawns;
int UB_ESCAPE = position.turn == WHITE_TURN ? 64 : -1;
int from = __builtin_ctzll(pawns);
pawns &= (pawns - 1);
int next_from = __builtin_ctzll(pawns);
if (pawns == 0) next_from = UB_ESCAPE;
while (item) {
int to = __builtin_ctzll(item);
if (pawn_in_range(to, next_from, UB_ESCAPE, position.turn)) {
from = next_from;
pawns &= (pawns - 1);
next_from = __builtin_ctzll(pawns);
if (pawns == 0) next_from = UB_ESCAPE;
}
item &= (item - 1);
if (to >= 56 || to <= 7) {
add_promote_moves(0);
} else add_move(moves, from, to);
}
}
if (position.passantable_file != 0) {
bitboard_t PASSANT_RANK;
int rank_shift;
int from_shift;
if (position.turn == WHITE_TURN) {
PASSANT_RANK = BITMASK_RANK_5;
rank_shift = 40;
from_shift = -9;
} else {
PASSANT_RANK = BITMASK_RANK_4;
from_shift = 7;
rank_shift = 16;
}
int left = 0, right = 0;
if (position.passantable_file > 1) left = position.passantable_file - 1;
if (position.passantable_file < 8) right = position.passantable_file + 1;
if (left != 0) {
bitboard_t MASK = file_masks[left - 1] & friendly_pawns & PASSANT_RANK;
if (MASK != 0) {
int from = left + rank_shift + from_shift;
int to = position.passantable_file + rank_shift - 1;
if (to >= 56 || to <= 7) {
add_promote_moves(MOVE_EN_PASSANT | MOVE_CAPTURE);
} else add_move(
moves, from, to, .flags = MOVE_EN_PASSANT | MOVE_CAPTURE
);
}
}
if (right != 0) {
bitboard_t MASK = file_masks[right - 1] & friendly_pawns & PASSANT_RANK;
if (MASK != 0) {
int from = right + rank_shift + from_shift;
int to = position.passantable_file + rank_shift - 1;
if (to >= 56 || to <= 7) {
add_promote_moves(MOVE_EN_PASSANT | MOVE_CAPTURE);
} else add_move(
moves, from, to, .flags = MOVE_EN_PASSANT | MOVE_CAPTURE
);
}
}
}
bitboard_t ATTACK_MASK;
int shift;
if (position.turn == WHITE_TURN) {
shift = 0;
} else {
shift = -16;
}
for (int i = 0; i < 8; i++) {
if (i == 0) ATTACK_MASK = 512;
else if (i == 7) ATTACK_MASK = 128;
else {
ATTACK_MASK = 640;
}
bitboard_t pawns = file_masks[i] & friendly_pawns;
while (pawns) {
int from = __builtin_ctzll(pawns);
pawns &= pawns - 1;
bitboard_t MASK;
if (from + shift > 0) {
MASK = ATTACK_MASK << (from + shift);
} else {
MASK = ATTACK_MASK >> -(from + shift);
}
MASK &= enemy_bitboard;
while (MASK) {
int to = __builtin_ctzll(MASK);
MASK &= MASK - 1;
if (to >= 56 || to <= 7) {
add_promote_moves(MOVE_CAPTURE);
} else add_move(moves, from, to, .flags = MOVE_CAPTURE);
}
}
}
}
|
