1/* 2 * libwebsockets - small server side websockets and web server implementation 3 * 4 * Copyright (C) 2010 - 2021 Andy Green <andy@warmcat.com> 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to 8 * deal in the Software without restriction, including without limitation the 9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 10 * sell copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 22 * IN THE SOFTWARE. 23 * 24 * After Public Domain implementations 25 * 26 * https://github.com/svaarala/duktape/tree/master/misc 27 */ 28 29#include <private-lib-core.h> 30 31static inline uint64_t rol64(uint64_t x, int k) 32{ 33 return (x << k) | (x >> (64 - k)); 34} 35 36uint64_t 37lws_xos(struct lws_xos *xos) 38{ 39 uint64_t *s = &xos->s[0]; 40 uint64_t const result = rol64(s[1] * 5, 7) * 9; 41 uint64_t const c = s[1] << 17; 42 43 s[2] ^= s[0]; 44 s[3] ^= s[1]; 45 s[1] ^= s[2]; 46 s[0] ^= s[3]; 47 48 s[2] ^= c; 49 s[3] = rol64(s[3], 45); 50 51 return result; 52} 53 54static uint64_t 55splitmix64(uint64_t *s) 56{ 57 uint64_t r = *s; 58 59 *s = r + 0x9E3779B97F4A7C15ull; 60 61 r = (r ^ (r >> 30)) * 0xBF58476D1CE4E5B9ull; 62 r = (r ^ (r >> 27)) * 0x94D049BB133111EBull; 63 64 return r ^ (r >> 31); 65} 66 67void 68lws_xos_init(struct lws_xos *xos, uint64_t seed) 69{ 70 int n; 71 72 for (n = 0; n < 4; n++) 73 xos->s[n] = splitmix64(&seed); 74} 75 76int 77lws_xos_percent(struct lws_xos *xos, int percent) 78{ 79 return (int)(lws_xos(xos) % 100) < percent; 80} 81