ndhc/nk/random.c
Nicholas J. Kain 8db8c5589d Replace CMake with GNU Make.
There was previously support for both build systems, but ndhc is
undemanding and there is no point in maintaining a complex
CMake build.
2022-01-22 18:39:41 -05:00

63 lines
2.2 KiB
C

/* random.c - non-cryptographic fast PRNG
*
* Copyright 2013-2018 Nicholas J. Kain <njkain at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdint.h>
#include "nk/hwrng.h"
#include "nk/random.h"
// GJrand64: https://gjrand.sourceforge.net
void nk_random_init(struct nk_random_state *s)
{
nk_get_hwrng(s->seed, sizeof(uint64_t) * 2);
s->seed[2] = 2000001;
s->seed[3] = 0;
for (size_t i = 0; i < 14; ++i) nk_random_u64(s);
}
static inline uint64_t rotl64(const uint64_t x, int k) {
return (x << k) | (x >> (64 - k));
}
uint64_t nk_random_u64(struct nk_random_state *s)
{
s->seed[1] += s->seed[2];
s->seed[0] = rotl64(s->seed[0], 32);
s->seed[2] ^= s->seed[1];
s->seed[3] += 0x55aa96a5;
s->seed[0] += s->seed[1];
s->seed[2] = rotl64(s->seed[2], 23);
s->seed[1] ^= s->seed[0];
s->seed[0] += s->seed[2];
s->seed[1] = rotl64(s->seed[1], 19);
s->seed[2] += s->seed[0];
s->seed[1] += s->seed[3];
return s->seed[0];
}