Adding examples to ChaChaRng
* Adds an example for creating an unseeded `ChaChaRng`.
* Adds an example for using `set_counter`.
diff --git a/src/chacha.rs b/src/chacha.rs
index 239f969..4a31baa 100644
--- a/src/chacha.rs
+++ b/src/chacha.rs
@@ -81,6 +81,22 @@
/// Create an ChaCha random number generator using the default
/// fixed key of 8 zero words.
+ ///
+ /// # Examples
+ ///
+ /// ```rust
+ /// use rand::{Rng, ChaChaRng};
+ ///
+ /// let mut ra = ChaChaRng::new_unseeded();
+ /// println!("{:?}", ra.next_u32());
+ /// println!("{:?}", ra.next_u32());
+ /// ```
+ ///
+ /// Since this equivalent to a RNG with a fixed seed, repeated executions
+ /// of an unseeded RNG will produce the same result. This code sample will
+ /// consistently produce:
+ /// - 2917185654
+ /// - 2419978656
pub fn new_unseeded() -> ChaChaRng {
let mut rng = EMPTY;
rng.init(&[0; KEY_WORDS]);
@@ -95,6 +111,17 @@
/// users wishing to obtain the conventional ChaCha pseudorandom stream
/// associated with a particular nonce can call this function with
/// arguments `0, desired_nonce`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use rand::{Rng, ChaChaRng};
+ ///
+ /// let mut ra = ChaChaRng::new_unseeded();
+ /// ra.set_counter(0u64, 1234567890u64);
+ /// println!("{:?}", ra.next_u32());
+ /// println!("{:?}", ra.next_u32());
+ /// ```
pub fn set_counter(&mut self, counter_low: u64, counter_high: u64) {
self.state[12] = w((counter_low >> 0) as u32);
self.state[13] = w((counter_low >> 32) as u32);
