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 | |
37 | static __inline uint64_t |
38 | rotl(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 | */ |
48 | void |
49 | dtrace_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 | */ |
76 | uint64_t |
77 | dtrace_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 | |