cosmopolitan/libc/rand/rand32.c

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2020-06-15 14:18:57 +00:00
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=8 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/dce.h"
#include "libc/nexgen32e/x86feature.h"
#include "libc/rand/rand.h"
#include "libc/rand/xorshift.h"
/**
* This function is an independent 32-bit clone of rand64().
*/
nodebuginfo uint32_t(rand32)(void) {
uint32_t res;
if (X86_HAVE(RDRND)) {
res = rdrand();
} else {
if (IsWindows()) {
res = kMarsagliaXorshift32Seed ^ winrandish();
} else {
devrand(&res, sizeof(res));
}
hidden extern uint32_t g_rando32;
res ^= MarsagliaXorshift32(&g_rando32);
}
return res;
}