Ply/magics.cpp at main · arnavlul/Ply · GitHub

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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
#include "magics.h"
#include <random>

namespace Magics {

    uint64_t ROOK_MASKS[64];
    uint64_t BISHOP_MASKS[64];
    uint64_t rookTable[64][4096];
    uint64_t bishopTable[64][512];

    uint64_t ROOK_MAGICS[64] = {
        0xa8002c000108020ULL, 0x6c00049b0002001ULL, 0x100200010090040ULL, 0x2480041000800801ULL,
        0x280028004000800ULL, 0x900410008040022ULL, 0x280020001001080ULL, 0x400080010004220ULL,
        0x1000c604130d0011ULL, 0x8480008080080081ULL, 0x2140023801100802ULL, 0x2008140041101ULL,
        0x8020008120008ULL, 0x2000812000100ULL, 0x100448100045ULL, 0x18000a120030ULL,
        0x108080800108020ULL, 0x6c08109024000301ULL, 0x80010090040ULL, 0x48045000800801ULL,
        0x28004000800ULL, 0x90041000804002ULL, 0x280020001001080ULL, 0x400080010004200ULL,
        0x40102011000040ULL, 0x801011000d1100ULL, 0x11002230110402ULL, 0x81000850304002ULL,
        0x4012820001001ULL, 0x401082000301ULL, 0x11008500041015ULL, 0x1105210040082ULL,
        0x20400080808080ULL, 0x10020200100080ULL, 0x800080800080ULL, 0x480020000440eULL,
        0x1000800020002ULL, 0x8000100020002ULL, 0x800010001000202ULL, 0x8000100010002ULL,
        0x20400080808080ULL, 0x10020200100080ULL, 0x800080800080ULL, 0x480020000440ULL,
        0x1000800020002ULL, 0x8000100020002ULL, 0x800010001000202ULL, 0x8000100010002ULL,
        0x20400080808080ULL, 0x10020200100080ULL, 0x800080800080ULL, 0x480020000440ULL,
        0x1000800020002ULL, 0x8000100020002ULL, 0x800010001000202ULL, 0x8000100010002ULL,
        0x20400080808080ULL, 0x10020200100080ULL, 0x800080800080ULL, 0x480020000440ULL,
        0x1000800020002ULL, 0x8000100020002ULL, 0x800010001000202ULL, 0x8000100010002ULL
    };

    uint64_t BISHOP_MAGICS[64] = {
        0x40040822104ULL, 0x40810a410800ULL, 0x2021000c01080ULL, 0x40102011000ULL,
        0x40102011000ULL, 0x2021000c01080ULL, 0x40810a410800ULL, 0x40040822104ULL,
        0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL,
        0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL,
        0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL,
        0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL,
        0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL,
        0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL,
        0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL,
        0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL, 0x4100410041ULL,
        0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL,
        0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL, 0x200100808204ULL,
        0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL,
        0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL, 0x4001021200ULL,
        0x40040822104ULL, 0x40810a410800ULL, 0x2021000c01080ULL, 0x40102011000ULL,
        0x40102011000ULL, 0x2021000c01080ULL, 0x40810a410800ULL, 0x40040822104ULL
    };

    const int ROOK_SHIFTS[64] = {
        52, 53, 53, 53, 53, 53, 53, 52,
        53, 54, 54, 54, 54, 54, 54, 53,
        53, 54, 54, 54, 54, 54, 54, 53,
        53, 54, 54, 54, 54, 54, 54, 53,
        53, 54, 54, 54, 54, 54, 54, 53,
        53, 54, 54, 54, 54, 54, 54, 53,
        53, 54, 54, 54, 54, 54, 54, 53,
        52, 53, 53, 53, 53, 53, 53, 52
    };

    const int BISHOP_SHIFTS[64] = {
        58, 59, 59, 59, 59, 59, 59, 58,
        59, 59, 59, 59, 59, 59, 59, 59,
        59, 59, 57, 57, 57, 57, 59, 59,
        59, 59, 57, 55, 55, 57, 59, 59,
        59, 59, 57, 55, 55, 57, 59, 59,
        59, 59, 57, 57, 57, 57, 59, 59,
        59, 59, 59, 59, 59, 59, 59, 59,
        58, 59, 59, 59, 59, 59, 59, 58
    };

    uint64_t rookMask(int sq) {
        uint64_t mask = 0;
        int r = sq / 8, f = sq % 8;
        for (int i = r + 1; i < 7; i++) mask |= (1ULL << (i * 8 + f));
        for (int i = r - 1; i > 0; i--) mask |= (1ULL << (i * 8 + f));
        for (int i = f + 1; i < 7; i++) mask |= (1ULL << (r * 8 + i));
        for (int i = f - 1; i > 0; i--) mask |= (1ULL << (r * 8 + i));
        return mask;
    }

    uint64_t bishopMask(int sq) {
        uint64_t mask = 0;
        int r = sq / 8, f = sq % 8;
        for (int i = r + 1, j = f + 1; i < 7 && j < 7; i++, j++) mask |= (1ULL << (i * 8 + j));
        for (int i = r + 1, j = f - 1; i < 7 && j > 0; i++, j--) mask |= (1ULL << (i * 8 + j));
        for (int i = r - 1, j = f + 1; i > 0 && j < 7; i--, j++) mask |= (1ULL << (i * 8 + j));
        for (int i = r - 1, j = f - 1; i > 0 && j > 0; i--, j--) mask |= (1ULL << (i * 8 + j));
        return mask;
    }

    uint64_t rookAttacksOnTheFly(int square, uint64_t occupancy) {
        uint64_t attacks = 0ULL;
        int tr = square / 8, tf = square % 8;
        for (int r = tr + 1; r <= 7; r++) { attacks |= (1ULL << (r * 8 + tf)); if (occupancy & (1ULL << (r * 8 + tf))) break; }
        for (int r = tr - 1; r >= 0; r--) { attacks |= (1ULL << (r * 8 + tf)); if (occupancy & (1ULL << (r * 8 + tf))) break; }
        for (int f = tf + 1; f <= 7; f++) { attacks |= (1ULL << (tr * 8 + f)); if (occupancy & (1ULL << (tr * 8 + f))) break; }
        for (int f = tf - 1; f >= 0; f--) { attacks |= (1ULL << (tr * 8 + f)); if (occupancy & (1ULL << (tr * 8 + f))) break; }
        return attacks;
    }

    uint64_t bishopAttacksOnTheFly(int square, uint64_t occupancy) {
        uint64_t attacks = 0ULL;
        int tr = square / 8, tf = square % 8;
        for (int r = tr + 1, f = tf + 1; r <= 7 && f <= 7; r++, f++) { attacks |= (1ULL << (r * 8 + f)); if (occupancy & (1ULL << (r * 8 + f))) break; }
        for (int r = tr + 1, f = tf - 1; r <= 7 && f >= 0; r++, f--) { attacks |= (1ULL << (r * 8 + f)); if (occupancy & (1ULL << (r * 8 + f))) break; }
        for (int r = tr - 1, f = tf + 1; r >= 0 && f <= 7; r--, f++) { attacks |= (1ULL << (r * 8 + f)); if (occupancy & (1ULL << (r * 8 + f))) break; }
        for (int r = tr - 1, f = tf - 1; r >= 0 && f >= 0; r--, f--) { attacks |= (1ULL << (r * 8 + f)); if (occupancy & (1ULL << (r * 8 + f))) break; }
        return attacks;
    }

    uint64_t setOccupancy(int index, int bitsInMask, uint64_t mask) {
        uint64_t occupancy = 0ULL;
        for (int i = 0; i < bitsInMask; i++) {
            int square = __builtin_ctzll(mask);
            mask &= (mask - 1);
            if (index & (1 << i)) occupancy |= (1ULL << square);
        }
        return occupancy;
    }

    uint64_t findMagic(int sq, int bits, bool bishop) {
        uint64_t mask = bishop ? bishopMask(sq) : rookMask(sq);
        int numOccupancies = 1 << bits;
        uint64_t occupancies[4096], attacks[4096], used[4096];
        bool occupied[4096];
        for (int i = 0; i < numOccupancies; i++) {
            occupancies[i] = setOccupancy(i, bits, mask);
            attacks[i] = bishop ? bishopAttacksOnTheFly(sq, occupancies[i]) : rookAttacksOnTheFly(sq, occupancies[i]);
        }
        std::mt19937_64 rng(sq + (bishop ? 64 : 0));
        while (true) {
            uint64_t magic = rng() & rng() & rng();
            if (__builtin_popcountll((mask * magic) & 0xFF00000000000000ULL) < 6) continue;
            for (int i = 0; i < numOccupancies; i++) occupied[i] = false;
            bool fail = false;
            for (int i = 0; i < numOccupancies; i++) {
                int index = (int)((occupancies[i] * magic) >> (64 - bits));
                if (!occupied[index]) {
                    occupied[index] = true;
                    used[index] = attacks[i];
                }
                else if (used[index] != attacks[i]) { fail = true; break; }
            }
            if (!fail) return magic;
        }
    }

    void init() {
        for (int i = 0; i < 64; i++) {
            ROOK_MASKS[i] = rookMask(i);
            BISHOP_MASKS[i] = bishopMask(i);

            int rookBits = 64 - ROOK_SHIFTS[i];
            int bishopBits = 64 - BISHOP_SHIFTS[i];

            // ROOK
            bool rookValid = true;
            for (int j = 0; j < (1 << rookBits); j++) {
                uint64_t occ = setOccupancy(j, rookBits, ROOK_MASKS[i]);
                int index = (int)((occ * ROOK_MAGICS[i]) >> ROOK_SHIFTS[i]);
                uint64_t atk = rookAttacksOnTheFly(i, occ);
                if (rookTable[i][index] == 0) rookTable[i][index] = atk;
                else if (rookTable[i][index] != atk) { rookValid = false; break; }
            }

            if (!rookValid) {
                ROOK_MAGICS[i] = findMagic(i, rookBits, false);
                for (int j = 0; j < 4096; j++) rookTable[i][j] = 0;
                for (int j = 0; j < (1 << rookBits); j++) {
                    uint64_t occ = setOccupancy(j, rookBits, ROOK_MASKS[i]);
                    int index = (int)((occ * ROOK_MAGICS[i]) >> ROOK_SHIFTS[i]);
                    rookTable[i][index] = rookAttacksOnTheFly(i, occ);
                }
            }

            // BISHOP
            bool bishopValid = true;
            for (int j = 0; j < (1 << bishopBits); j++) {
                uint64_t occ = setOccupancy(j, bishopBits, BISHOP_MASKS[i]);
                int index = (int)((occ * BISHOP_MAGICS[i]) >> BISHOP_SHIFTS[i]);
                uint64_t atk = bishopAttacksOnTheFly(i, occ);
                if (bishopTable[i][index] == 0) bishopTable[i][index] = atk;
                else if (bishopTable[i][index] != atk) { bishopValid = false; break; }
            }

            if (!bishopValid) {
                BISHOP_MAGICS[i] = findMagic(i, bishopBits, true);
                for (int j = 0; j < 512; j++) bishopTable[i][j] = 0;
                for (int j = 0; j < (1 << bishopBits); j++) {
                    uint64_t occ = setOccupancy(j, bishopBits, BISHOP_MASKS[i]);
                    int index = (int)((occ * BISHOP_MAGICS[i]) >> BISHOP_SHIFTS[i]);
                    bishopTable[i][index] = bishopAttacksOnTheFly(i, occ);
                }
            }
        }
    }

}