1/*-
2 * Copyright (c) 2016 (Graeme Jenkinson)
3 * All rights reserved.
4 *
5 * This software was developed by BAE Systems, the University of Cambridge
6 * Computer Laboratory, and Memorial University under DARPA/AFRL contract
7 * FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent Computing
8 * (TC) research program.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 */
32
33#include <sys/types.h>
34
35#include "dtrace_xoroshiro128_plus.h"
36
37static __inline uint64_t
38rotl(const uint64_t x, int k)
39{
40 return (x << k) | (x >> (64 - k));
41}
42
43/*
44 * This is the jump function for the generator. It is equivalent to 2^64 calls
45 * to next(); it can be used to generate 2^64 non-overlapping subsequences for
46 * parallel computations.
47 */
48void
49dtrace_xoroshiro128_plus_jump(uint64_t * const state,
50 uint64_t * const jump_state)
51{
52 static const uint64_t JUMP[] = { 0xbeac0467eba5facb,
53 0xd86b048b86aa9922 };
54
55 uint64_t s0 = 0;
56 uint64_t s1 = 0;
57 size_t i = 0;
58 int b = 0;
59 for (i = 0; i < sizeof JUMP / sizeof *JUMP; i++) {
60 for (b = 0; b < 64; b++) {
61 if (JUMP[i] & 1ULL << b) {
62 s0 ^= state[0];
63 s1 ^= state[1];
64 }
65 dtrace_xoroshiro128_plus_next(state);
66 }
67 }
68 jump_state[0] = s0;
69 jump_state[1] = s1;
70}
71
72/*
73 * xoroshiro128+ - XOR/rotate/shift/rotate
74 * xorshift.di.unimi.it
75 */
76uint64_t
77dtrace_xoroshiro128_plus_next(uint64_t * const state)
78{
79 const uint64_t s0 = state[0];
80 uint64_t s1 = state[1];
81 uint64_t result;
82 result = s0 + s1;
83
84 s1 ^= s0;
85 state[0] = rotl(x: s0, k: 55) ^ s1 ^ (s1 << 14);
86 state[1] = rotl(x: s1, k: 36);
87
88 return result;
89}
90