1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
// Copyright 2017 Steven Stewart-Gallus // // See the COPYRIGHT file at the top-level directory of this // distribution. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or // implied. See the License for the specific language governing // permissions and limitations under the License. // #![feature(thread_local)] extern crate rand; struct Rng { init: bool, state: u64, } // Use MMIX RNG #[thread_local] static mut RNG: Rng = Rng { init: false, state: 0, }; #[cold] fn init() -> u64 { rand::random() } #[inline] pub fn rand(min: u64, max: u64) -> u64 { unsafe { if !RNG.init { RNG.init = true; RNG.state = init(); } let old = RNG.state; let new = old.wrapping_mul(6364136223846793005).wrapping_add(1442695040888963407); RNG.state = new; return (old % (max.wrapping_add(1).wrapping_sub(min))).wrapping_add(min); } }