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 int 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(s0, 55) ^ s1 ^ (s1 << 14); 86 state[1] = rotl(s1, 36); 87 88 return result; 89 } 90