/*-
* Copyright (c) 2016 (Graeme Jenkinson)
* All rights reserved.
*
* This software was developed by BAE Systems, the University of Cambridge
* Computer Laboratory, and Memorial University under DARPA/AFRL contract
* FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent Computing
* (TC) research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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 AUTHOR 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 AUTHOR 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 <sys/types.h>
#include "dtrace_xoroshiro128_plus.h"
static __inline uint64_t
rotl(const uint64_t x, int k)
{
return (x << k) | (x >> (64 - k));
}
/*
* This is the jump function for the generator. It is equivalent to 2^64 calls
* to next(); it can be used to generate 2^64 non-overlapping subsequences for
* parallel computations.
*/
void
dtrace_xoroshiro128_plus_jump(uint64_t * const state,
uint64_t * const jump_state)
{
static const uint64_t JUMP[] = { 0xbeac0467eba5facb,
0xd86b048b86aa9922 };
uint64_t s0 = 0;
uint64_t s1 = 0;
int i = 0;
int b = 0;
for (i = 0; i < sizeof JUMP / sizeof *JUMP; i++) {
for (b = 0; b < 64; b++) {
if (JUMP[i] & 1ULL << b) {
s0 ^= state[0];
s1 ^= state[1];
}
dtrace_xoroshiro128_plus_next(state);
}
}
jump_state[0] = s0;
jump_state[1] = s1;
}
/*
* xoroshiro128+ - XOR/rotate/shift/rotate
* xorshift.di.unimi.it
*/
uint64_t
dtrace_xoroshiro128_plus_next(uint64_t * const state)
{
const uint64_t s0 = state[0];
uint64_t s1 = state[1];
uint64_t result;
result = s0 + s1;
s1 ^= s0;
state[0] = rotl(s0, 55) ^ s1 ^ (s1 << 14);
state[1] = rotl(s1, 36);
return result;
}
