block/include/nil/crypto3/detail/primes.hpp

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//---------------------------------------------------------------------------//
// Copyright (c) 2018-2020 Mikhail Komarov <nemo@nil.foundation>
//
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//---------------------------------------------------------------------------//
 
#ifndef CRYPTO3_DETAIL_PRIMES_HPP
#define CRYPTO3_DETAIL_PRIMES_HPP
 
#include <boost/integer.hpp>
 
namespace nil {
    namespace crypto3 {
        namespace detail {
 
            template<int Bits>
            struct all_ones {
                typedef typename boost::uint_t<Bits>::least type;
                static type const value = (all_ones<Bits - 1>::value << 1) | 1;
            };
            template<>
            struct all_ones<0> {
                typedef boost::uint_t<0>::least type;
                static type const value = 0;
            };
 
            template<int Bits>
            struct largest_prime;
 
#define CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(B, D)                              \
    template<>                                                                         \
    struct largest_prime<B> {                                                          \
        constexpr static boost::uint_t<B>::least const value = all_ones<B>::value - D; \
    };                                                                                 \
    constexpr boost::uint_t<B>::least const largest_prime<B>::value;
 
            // http://primes.utm.edu/lists/2small/0bit.html or
            // http://www.research.att.com/~njas/sequences/A013603
            // Though those offets are from 2**b; This code is offsets from 2**b-1
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(2, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(3, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(4, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(5, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(6, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(7, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(8, 4);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(9, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(10, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(11, 8);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(12, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(13, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(14, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(15, 18);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(16, 14);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(17, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(18, 4);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(19, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(20, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(21, 8);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(22, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(23, 14);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(24, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(25, 38);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(26, 4);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(27, 38);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(28, 56);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(29, 2);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(30, 34);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(31, 0);
            CRYPTO3_HASH_DEFINE_LARGEST_PRIME_BY_OFFSET(32, 4);
 
        }    // namespace detail
    }        // namespace crypto3
}    // namespace nil
 
#endif    // CRYPTO3_HASH_DETAIL_PRIMES_HPP