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| 1 | +#ifndef CP_ALGO_NUMBER_THEORY_NIMBER_HPP |
| 2 | +#define CP_ALGO_NUMBER_THEORY_NIMBER_HPP |
| 3 | +#include <array> |
| 4 | +#include <bit> |
| 5 | +#include <cstdint> |
| 6 | +#include <immintrin.h> |
| 7 | +// Ensure PCLMULQDQ is available at compile time |
| 8 | +#if defined(__PCLMUL__) |
| 9 | +static constexpr bool CP_ALGO_HAS_PCLMUL = true; |
| 10 | +#else |
| 11 | +static constexpr bool CP_ALGO_HAS_PCLMUL = false; |
| 12 | +#endif |
| 13 | +static_assert(CP_ALGO_HAS_PCLMUL, |
| 14 | + "PCLMULQDQ intrinsics not available. Enable it with '-mpclmul' or add '#pragma GCC target(\"pclmul\")' or compile with '-march=native' on supported CPUs."); |
| 15 | + |
| 16 | +namespace cp_algo::math::nimber { |
| 17 | + inline constexpr std::array<uint64_t, 64> BASIS_COL = { |
| 18 | + 0x0000000000000001ull, 0x5211145c804b6109ull, 0x7c8bc2cad259879full, 0x565854b4c60c1e0bull, |
| 19 | + 0x4068acf7104c20c3ull, 0x662d2bd0f2739155ull, 0x7a90c83701fa8323ull, 0x21cfa750247e8755ull, |
| 20 | + 0x67d1044e545abf47ull, 0x4d9d3b5a8568f839ull, 0x567a9d7331b6b3c6ull, 0x1ca54bfdd6d1ae59ull, |
| 21 | + 0x454fa483275db25cull, 0x6766df6fec4e9d44ull, 0x35cb621cec1fe7f9ull, 0x4c606d3e52faf263ull, |
| 22 | + 0x57640dc825a57954ull, 0x7aca87838b7f6315ull, 0x6d53c884ebf2b0edull, 0x3721d998bb50164bull, |
| 23 | + 0x7aa7c62fd6cd53abull, 0x47cbb2c51f7c040full, 0x132063b7f5e42489ull, 0x0c1b36c8b2993f8aull, |
| 24 | + 0x60119ecff680497aull, 0x5175da444cc11791ull, 0x5792ff4554765b09ull, 0x0c9fdb8a01334e82ull, |
| 25 | + 0x2be0a763a68a4725ull, 0x3c2dc8260ad051f6ull, 0x6c4c9fed8816bb9cull, 0x630062753ffaf766ull, |
| 26 | + 0x7b37d31b5d519225ull, 0x2364f7f79705691cull, 0x453eb8a83e2fec71ull, 0x7c0121b37e828666ull, |
| 27 | + 0x59190d3250e66011ull, 0x103207f9dda18caeull, 0x28233dce01c69b76ull, 0x4fa519899227a5e7ull, |
| 28 | + 0x4567ba46ee7bc6cdull, 0x0a284773d021afd5ull, 0x63894079bbe3a824ull, 0x11013c7fdfaaa5c2ull, |
| 29 | + 0x1aa984f18574f3b0ull, 0x0cbaba126fd0c4dbull, 0x0b8797719e6dc725ull, 0x4a2845680aefaa72ull, |
| 30 | + 0x536d2535f6934e15ull, 0x01db7a57effcd689ull, 0x7e1ed0ad01e2a5adull, 0x0aedc9b3cee826f6ull, |
| 31 | + 0x7ba716eccf9f68e1ull, 0x5d5e23bc0f3dc38full, 0x0b5f2a3b88674d83ull, 0x2de9bafc2f00f8d4ull, |
| 32 | + 0x3b56712ad419c7e0ull, 0x3ab4be8c30c19253ull, 0x2708522ffaa654b0ull, 0x2b8bca57bf643598ull, |
| 33 | + 0x588825d1a5fa8e1cull, 0x86adf8bf4d45962full, 0x51b4c15d8719dd73ull, 0xe4a2b3b59783d0aaull |
| 34 | + }; |
| 35 | + |
| 36 | + inline constexpr std::array<uint64_t, 64> INV_COL = { |
| 37 | + 0x0000000000000001ull, 0x19c9369f278adc02ull, 0xa181e7d66f5ff795ull, 0x5db84357ce785d09ull, |
| 38 | + 0xa0bae2f9d2430cc8ull, 0xb7ea5a9705b771c0ull, 0xba4f3cd82801769dull, 0x4886cde01b8241d0ull, |
| 39 | + 0x0a6f43f2aaf612edull, 0xebd0142f98030a32ull, 0xa81f89cda43f3792ull, 0xe99aec6b66ccb814ull, |
| 40 | + 0xa69d1ff025fc2f82ull, 0x48a81132d25db068ull, 0x4a900f9dcaa9644full, 0xe5ce4ea88259972aull, |
| 41 | + 0xf7094c336029f04cull, 0xe191dde287bc9c6bull, 0xaacaff12bff239b8ull, 0x49bc5212be1bc1caull, |
| 42 | + 0xfe57defb454446cfull, 0xa1dffcf944bdf6a7ull, 0xb9f1bdb5cee941eeull, 0x12e5e889275c22deull, |
| 43 | + 0x5bcb6b117b77eeedull, 0x03eb1ab59d05ae4bull, 0x02a25d7076ddd386ull, 0x53164a606c612245ull, |
| 44 | + 0xebb33f5822f66059ull, 0xe9be765f5747b93eull, 0x552a78df373a354full, 0xbcf5ac65f31fb8bfull, |
| 45 | + 0xe411e728becdc77bull, 0xf35c26d7b57cdca6ull, 0x4499da83de4ca5f7ull, 0x40ab25bdca4ae226ull, |
| 46 | + 0xee004b6f1dff7218ull, 0x0d122da9821c5b41ull, 0x51fbfcb058120efeull, 0xa148b1fa84905b22ull, |
| 47 | + 0xbb8ed3e647604d8dull, 0xe2d93fef2472776full, 0x4c17a2541a10e6b5ull, 0x1d879e08903708e7ull, |
| 48 | + 0x0fbe7d0d1934da90ull, 0x5bf977d9c6f61d30ull, 0x06832fc918260412ull, 0x0fe22e843ebf73e3ull, |
| 49 | + 0x4d7ef4e4fa28d60dull, 0x402250d979afbed5ull, 0x067902b8c8ca2d4full, 0xf38d113fe1d6bb16ull, |
| 50 | + 0x414f0248b02b5b7dull, 0xf041922915824ce9ull, 0x11a72fb5e30c93d9ull, 0x12e54f4d63102aeeull, |
| 51 | + 0xbc46ac14b3141c6cull, 0x1f172b3c16c645bbull, 0x584b492ed4e8fa6cull, 0x00a852e9a32cc133ull, |
| 52 | + 0xa180861bce00a45eull, 0xa194b6bcb4645fb9ull, 0x4509002ad808a4fbull, 0xc5172a0055602f69ull |
| 53 | + }; |
| 54 | + |
| 55 | + template <const auto& COLS> |
| 56 | + consteval auto make_byte_tables() { |
| 57 | + std::array<std::array<uint64_t, 1 << 8>, 8> T{}; |
| 58 | + for (int pos = 0; pos < 8; pos++) { |
| 59 | + for (int col = 0; col < 8; col++) { |
| 60 | + for (int mask = 0; mask < (1 << col); mask++) { |
| 61 | + T[pos][mask | (1 << col)] = T[pos][mask] ^ COLS[pos * 8 + col]; |
| 62 | + } |
| 63 | + } |
| 64 | + } |
| 65 | + return T; |
| 66 | + } |
| 67 | + |
| 68 | + inline constexpr auto INV_BYTE = make_byte_tables<INV_COL>(); |
| 69 | + inline constexpr auto BASIS_BYTE = make_byte_tables<BASIS_COL>(); |
| 70 | + |
| 71 | + [[gnu::always_inline]] |
| 72 | + inline uint64_t nim_to_poly(uint64_t x) { |
| 73 | + auto xb = std::bit_cast<std::array<uint8_t, 8>>(x); |
| 74 | + return INV_BYTE[0][xb[0]] ^ INV_BYTE[1][xb[1]] |
| 75 | + ^ INV_BYTE[2][xb[2]] ^ INV_BYTE[3][xb[3]] |
| 76 | + ^ INV_BYTE[4][xb[4]] ^ INV_BYTE[5][xb[5]] |
| 77 | + ^ INV_BYTE[6][xb[6]] ^ INV_BYTE[7][xb[7]]; |
| 78 | + } |
| 79 | + |
| 80 | + [[gnu::always_inline]] |
| 81 | + inline uint64_t poly_to_nim(uint64_t c) { |
| 82 | + auto cb = std::bit_cast<std::array<uint8_t, 8>>(c); |
| 83 | + return BASIS_BYTE[0][cb[0]] ^ BASIS_BYTE[1][cb[1]] |
| 84 | + ^ BASIS_BYTE[2][cb[2]] ^ BASIS_BYTE[3][cb[3]] |
| 85 | + ^ BASIS_BYTE[4][cb[4]] ^ BASIS_BYTE[5][cb[5]] |
| 86 | + ^ BASIS_BYTE[6][cb[6]] ^ BASIS_BYTE[7][cb[7]]; |
| 87 | + } |
| 88 | + |
| 89 | + // Carryless multiply over GF(2) using PCLMULQDQ |
| 90 | + [[gnu::always_inline]] |
| 91 | + inline __m128i clmul(int64_t a, int64_t b) { |
| 92 | + return _mm_clmulepi64_si128(__m128i{a, 0}, __m128i{b, 0}, 0); |
| 93 | + } |
| 94 | + |
| 95 | + // Reduce modulo x^64 + x^4 + x^3 + x + 1 |
| 96 | + [[gnu::always_inline]] |
| 97 | + inline uint64_t reduce_mod(__m128i v) { |
| 98 | + v[0] ^= v[1] ^ (v[1] << 1) ^ (v[1] << 3) ^ (v[1] << 4); |
| 99 | + static constexpr auto RED_OVER = [] { |
| 100 | + std::array<uint64_t, 16> red{}; |
| 101 | + for (int q = 0; q < 16; ++q) { |
| 102 | + uint64_t o = q ^ (q >> 1) ^ (q >> 3); |
| 103 | + red[q] = o ^ (o << 1) ^ (o << 3) ^ (o << 4); |
| 104 | + } |
| 105 | + return red; |
| 106 | + }(); |
| 107 | + return v[0] ^ RED_OVER[v[1] >> 60]; |
| 108 | + } |
| 109 | + |
| 110 | + // Public nimber product via isomorphism (no recursion, no Gauss at runtime) |
| 111 | + [[gnu::always_inline]] |
| 112 | + inline uint64_t nim_mul(uint64_t a, uint64_t b) { |
| 113 | + uint64_t pa = nim_to_poly(a); |
| 114 | + uint64_t pb = nim_to_poly(b); |
| 115 | + auto prod = clmul(pa, pb); |
| 116 | + uint64_t red = reduce_mod(prod); |
| 117 | + return poly_to_nim(red); |
| 118 | + } |
| 119 | +} |
| 120 | + |
| 121 | +#endif // CP_ALGO_NUMBER_THEORY_NIMBER_HPP |
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