mirror of
https://github.com/jart/cosmopolitan.git
synced 2024-05-17 02:52:40 +00:00
2ab9e9f7fd
- Introduce portable sched_getcpu() api - Support GCC's __target_clones__ feature - Make fma() go faster on x86 in default mode - Remove some asan checks from core libraries - WinMain() now ensures $HOME and $USER are defined
92 lines
3.8 KiB
C
92 lines
3.8 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 2020 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/calls/calls.h"
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#include "libc/dce.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/stdio/rand.h"
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#include "libc/stdio/stdio.h"
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/**
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* Fills memory with random bytes, e.g.
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*
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* char buf[512];
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* rngset(buf, sizeof(buf), 0, 0);
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*
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* If reseed is zero then the internal PRNG is disabled and bytes are
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* simply copied in little-endian order from the seed function. If seed
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* is NULL then the reseed parameter is used as the seed value for the
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* internal PRNG. If seed!=NULL and reseed>8 then reseed is the number
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* of bytes after which the seed() function should be called again, to
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* freshen up the PRNG.
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*
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* The main advantage of this generator is that it produces data at 13
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* gigabytes per second since Vigna's Algorithm vectorizes better than
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* alternatives, going even faster than xorshift.
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*
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* @return original buf
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*/
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dontasan void *rngset(void *b, size_t n, uint64_t seed(void), size_t reseed) {
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size_t m;
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uint64_t x, t = 0;
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unsigned char *p = b;
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if (!seed) {
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t = reseed;
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reseed = -1;
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} else if (reseed < 8) {
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reseed = 8;
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}
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while (n) {
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if (seed) t = seed();
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if (!seed || reseed > 8) {
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n -= (m = reseed < n ? reseed : n);
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while (m >= 8) {
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x = (t += 0x9e3779b97f4a7c15);
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x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
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x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
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x = (x ^ (x >> 31));
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__builtin_memcpy(p, &x, 8);
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p += 8;
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m -= 8;
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}
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while (m--) {
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*p++ = t;
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t >>= 8;
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}
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} else if (n >= 8) {
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p[0] = (0x00000000000000FF & t) >> 000;
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p[1] = (0x000000000000FF00 & t) >> 010;
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p[2] = (0x0000000000FF0000 & t) >> 020;
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p[3] = (0x00000000FF000000 & t) >> 030;
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p[4] = (0x000000FF00000000 & t) >> 040;
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p[5] = (0x0000FF0000000000 & t) >> 050;
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p[6] = (0x00FF000000000000 & t) >> 060;
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p[7] = (0xFF00000000000000 & t) >> 070;
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p += 8;
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n -= 8;
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} else {
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while (n) {
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*p++ = t;
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t >>= 8;
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--n;
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}
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}
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}
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return b;
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}
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