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// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use io;
use rand::Rng;
// FIXME: Use rand:
pub struct OsRng {
state: [u64; 2]
}
impl OsRng {
/// Create a new `OsRng`.
pub fn new() -> io::Result<OsRng> {
Ok(OsRng {
state: [0xBADF00D1, 0xDEADBEEF]
})
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
self.next_u64() as u32
}
fn next_u64(&mut self) -> u64 {
// Store the first and second part.
let mut x = self.state[0];
let y = self.state[1];
// Put the second part into the first slot.
self.state[0] = y;
// Twist the first slot.
x ^= x << 23;
// Update the second slot.
self.state[1] = x ^ y ^ (x >> 17) ^ (y >> 26);
// Generate the final integer.
self.state[1].wrapping_add(y)
}
fn fill_bytes(&mut self, buf: &mut [u8]) {
for chunk in buf.chunks_mut(8) {
let mut rand: u64 = self.next_u64();
for b in chunk.iter_mut() {
*b = rand as u8;
rand = rand >> 8;
}
}
}
}
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