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e16a7d8f3b
`et` means `expandtab`. ```sh rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\) :vi/vi: \1 xoet\2:vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2 :vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/' ```
79 lines
3.4 KiB
C
79 lines
3.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/stdio/rand.h"
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static uint64_t g_vigna;
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/**
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* Returns deterministic pseudorandom data, e.g.
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*
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* uint64_t x = vigna();
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*
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* You can generate different types of numbers as follows:
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*
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* int64_t x = vigna() >> 1; // make positive signed integer
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* double x = _real1(vigna()); // make float on [0,1]-interval
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*
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* You can seed this random number generator using:
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*
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* svigna(rdseed());
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*
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* You may use the reentrant version of this function:
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*
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* static uint64_t s = 0;
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* uint64_t x = svigna_r(&s);
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*
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* If you want to fill a buffer with data then rngset() implements
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* vigna's algorithm to do that extremely well:
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*
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* char buf[4096];
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* rngset(buf, sizeof(buf), vigna, 0);
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*
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* If you want a fast pseudorandom number generator that seeds itself
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* automatically on startup and fork(), then consider _rand64. If you
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* want true random data then consider rdseed, rdrand, and getrandom.
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*
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* @return 64 bits of pseudorandom data
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* @note this function is not intended for cryptography
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* @note this function passes bigcrush and practrand
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* @note this function takes at minimum 4 cycles
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*/
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uint64_t vigna(void) {
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return vigna_r(&g_vigna);
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}
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/**
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* Returns pseudorandom data.
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* @see vigna() for easy api
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*/
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uint64_t vigna_r(uint64_t state[hasatleast 1]) {
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uint64_t z = (state[0] += 0x9e3779b97f4a7c15);
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z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
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z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
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return z ^ (z >> 31);
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}
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/**
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* Seeds vigna() pseudorandom number generator.
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* @see vigna(), vigna_r()
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*/
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void svigna(uint64_t seed) {
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g_vigna = seed;
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}
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