cosmopolitan/libc/rand/g_rando64.c

49 lines
2.7 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/bits.h"
#include "libc/dce.h"
#include "libc/rand/rand.h"
#include "libc/rand/xorshift.h"
#include "libc/sysv/consts/auxv.h"
hidden uint64_t g_rando64;
textstartup static void g_rando64_init() {
register intptr_t *auxv asm("r15"); /* @see libc/crt/crt.S */
asm volatile("" : "=r"(auxv));
if (!IsXnu() && !IsWindows()) {
for (intptr_t *auxvp = auxv; auxvp[0]; auxvp += 2) {
if (auxvp[0] == AT_RANDOM) {
uint8_t(*sysrandseed)[16] = (uint8_t(*)[16])auxvp[1];
if (sysrandseed) g_rando64 ^= read64le(&(*sysrandseed)[0]);
return;
}
}
}
g_rando64 ^= kMarsagliaXorshift64Seed;
if (IsWindows()) {
g_rando64 ^= winrandish();
} else {
devrand(&g_rando64, sizeof(g_rando64));
}
}
const void *const g_rando64_ctor[] initarray = {g_rando64_init};