65 lines
1.7 KiB
C++
65 lines
1.7 KiB
C++
/* ethash: C/C++ implementation of Ethash, the Ethereum Proof of Work algorithm.
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* Copyright 2018 Pawel Bylica.
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* Licensed under the Apache License, Version 2.0. See the LICENSE file.
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*/
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#pragma once
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#include "support/attributes.h"
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#include <stdint.h>
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/**
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* KISS PRNG by the spec from 1999.
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*
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* The implementation of KISS pseudo-random number generator
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* by the specification published on 21 Jan 1999 in
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* http://www.cse.yorku.ca/~oz/marsaglia-rng.html.
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* The KISS is not versioned so here we are using `kiss99` prefix to indicate
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* the version from 1999.
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*
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* The specification uses `unsigned long` type with the intention for 32-bit
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* values. Because in GCC/clang for 64-bit architectures `unsigned long` is
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* 64-bit size type, here the explicit `uint32_t` type is used.
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*
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* @defgroup kiss99 KISS99
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* @{
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*/
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/**
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* The KISS generator.
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*/
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class kiss99
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{
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uint32_t z = 362436069;
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uint32_t w = 521288629;
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uint32_t jsr = 123456789;
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uint32_t jcong = 380116160;
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public:
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/** Creates KISS generator state with default values provided by the specification. */
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kiss99() noexcept = default;
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/** Creates KISS generator state with provided init values.*/
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kiss99(uint32_t z, uint32_t w, uint32_t jsr, uint32_t jcong) noexcept
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: z{z}, w{w}, jsr{jsr}, jcong{jcong}
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{}
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/** Generates next number from the KISS generator. */
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NO_SANITIZE("unsigned-integer-overflow")
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uint32_t operator()() noexcept
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{
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z = 36969 * (z & 0xffff) + (z >> 16);
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w = 18000 * (w & 0xffff) + (w >> 16);
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jcong = 69069 * jcong + 1234567;
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jsr ^= (jsr << 17);
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jsr ^= (jsr >> 13);
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jsr ^= (jsr << 5);
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return (((z << 16) + w) ^ jcong) + jsr;
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}
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};
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/** @} */
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