71 lines
2.3 KiB
C++
71 lines
2.3 KiB
C++
#include "tb.h"
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#include <stdint.h>
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// TB pseudorandom number generator, using xoroshiro256++ -- original
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// copyright notice follows.
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/* Written in 2019 by David Blackman and Sebastiano Vigna (vigna@acm.org)
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To the extent possible under law, the author has dedicated all copyright
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and related and neighboring rights to this software to the public domain
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worldwide.
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
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IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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/* This is xoshiro256++ 1.0, one of our all-purpose, rock-solid generators.
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It has excellent (sub-ns) speed, a state (256 bits) that is large
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enough for any parallel application, and it passes all tests we are
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aware of.
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For generating just floating-point numbers, xoshiro256+ is even faster.
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The state must be seeded so that it is not everywhere zero. If you have
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a 64-bit seed, we suggest to seed a splitmix64 generator and use its
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output to fill s. */
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static inline uint64_t rotl(const uint64_t x, int k) {
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return (x << k) | (x >> (64 - k));
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}
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uint32_t tb_top::rand(void) {
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const uint64_t result = rotl(rand_state[0] + rand_state[3], 23) + rand_state[0];
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const uint64_t t = rand_state[1] << 17;
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rand_state[2] ^= rand_state[0];
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rand_state[3] ^= rand_state[1];
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rand_state[1] ^= rand_state[2];
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rand_state[0] ^= rand_state[3];
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rand_state[2] ^= t;
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rand_state[3] = rotl(rand_state[3], 45);
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return result >> 32;
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}
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void tb_top::seed_rand(const uint8_t *data, size_t len) {
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// Initial state must not be all-zeroes
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for (unsigned int i = 0; i < 4; ++i) {
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rand_state[i] = 0xf005ba11u + i;
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}
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// Pour + stir method: XOR data in one bit at a time, with a xoroshiro
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// permutation between each.
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for (size_t i = 0; i < 8u * len; ++i) {
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if (data[i / 8u] & (1u << (i % 8u))) {
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rand_state[0] ^= 1u;
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}
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(void)rand();
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}
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}
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