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git-subtree-dir: src/minisketch git-subtree-split: 89629eb2c7e262b39ba489b93b111760baded4b3
71 lines
2.3 KiB
C++
71 lines
2.3 KiB
C++
/**********************************************************************
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* Copyright (c) 2018 Pieter Wuille, Greg Maxwell, Gleb Naumenko *
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* Distributed under the MIT software license, see the accompanying *
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* file LICENSE or http://www.opensource.org/licenses/mit-license.php.*
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**********************************************************************/
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#ifndef _MINISKETCH_FIELDS_GENERIC_COMMON_IMPL_H_
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#define _MINISKETCH_FIELDS_GENERIC_COMMON_IMPL_H_ 1
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#include <stdint.h>
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#include "../int_utils.h"
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#include "../lintrans.h"
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namespace {
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/** Generic implementation for fields whose elements can be represented by an integer type. */
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template<typename I, int B, uint32_t MOD, typename F, typename T, const F* SQR, const F* QRT> class Field
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{
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typedef BitsInt<I, B> O;
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typedef LFSR<O, MOD> L;
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public:
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typedef I Elem;
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constexpr int Bits() const { return B; }
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constexpr inline Elem Mul2(Elem val) const { return L::Call(val); }
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class Multiplier
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{
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T table;
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public:
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explicit Multiplier(const Field&, Elem a) { table.template Build<L::Call>(a); }
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constexpr inline Elem operator()(Elem a) const { return table.template Map<O>(a); }
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};
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Elem Mul(Elem a, Elem b) const { return GFMul<I, B, L, O>(a, b); }
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/** Compute the square of a. */
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inline constexpr Elem Sqr(Elem a) const { return SQR->template Map<O>(a); }
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/** Compute x such that x^2 + x = a (undefined result if no solution exists). */
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inline constexpr Elem Qrt(Elem a) const { return QRT->template Map<O>(a); }
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/** Compute the inverse of x1. */
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Elem Inv(Elem a) const { return InvExtGCD<I, O, B, MOD>(a); }
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/** Generate a random field element. */
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Elem FromSeed(uint64_t seed) const {
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uint64_t k0 = 0x496e744669656c64ull; // "IntField"
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uint64_t k1 = seed;
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uint64_t count = ((uint64_t)B) << 32;
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Elem ret;
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do {
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ret = O::Mask(I(SipHash(k0, k1, count++)));
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} while(ret == 0);
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return ret;
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}
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Elem Deserialize(BitReader& in) const { return in.template Read<B, I>(); }
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void Serialize(BitWriter& out, Elem val) const { out.template Write<B, I>(val); }
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constexpr Elem FromUint64(uint64_t x) const { return O::Mask(I(x)); }
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constexpr uint64_t ToUint64(Elem val) const { return uint64_t(val); }
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};
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}
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#endif
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