Struct rand_core::block::BlockRng64

pub struct BlockRng64<R: BlockRngCore + ?Sized> {
    results: R::Results,
    index: usize,
    half_used: bool,
    pub core: R,
}

A wrapper type implementing RngCore for some type implementing BlockRngCore with u64 array buffer; i.e. this can be used to implement a full RNG from just a generate function.

This is similar to BlockRng, but specialized for algorithms that operate on u64 values.

No whole generated u64 values are thrown away and all values are consumed in-order. next_u64 simply takes the next available u64 value. next_u32 is however a bit special: half of a u64 is consumed, leaving the other half in the buffer. If the next function called is next_u32 then the other half is then consumed, however both next_u64 and fill_bytes discard the rest of any half-consumed u64s when called.

fill_bytes and try_fill_bytes consume a whole number of u64 values. If the requested length is not a multiple of 8, some bytes will be discarded.

Fields

results: R::Results

index: usize

half_used: bool

core: R

The core part of the RNG, implementing the generate function.

Implementations

impl<R: BlockRngCore> BlockRng64<R>

pub fn new(core: R) -> BlockRng64<R>

Create a new BlockRng from an existing RNG implementing BlockRngCore. Results will be generated on first use.

pub fn index(&self) -> usize

Get the index into the result buffer.

If this is equal to or larger than the size of the result buffer then the buffer is “empty” and generate() must be called to produce new results.

pub fn reset(&mut self)

Reset the number of available results. This will force a new set of results to be generated on next use.

pub fn generate_and_set(&mut self, index: usize)

Generate a new set of results immediately, setting the index to the given value.

Trait Implementations

impl<R: Clone + BlockRngCore + ?Sized> Clone for BlockRng64<R>

where R::Results: Clone,

fn clone(&self) -> BlockRng64<R>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<R: BlockRngCore + Debug> Debug for BlockRng64<R>

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<R: BlockRngCore<Item = u64>> RngCore for BlockRng64<R>

where <R as BlockRngCore>::Results: AsRef<[u64]> + AsMut<[u64]>,

fn next_u32(&mut self) -> u32

Return the next random u32.

fn next_u64(&mut self) -> u64

Return the next random u64.

fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data.

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill dest entirely with random data.

impl<R: BlockRngCore + SeedableRng> SeedableRng for BlockRng64<R>

type Seed = <R as SeedableRng>::Seed

Seed type, which is restricted to types mutably-dereferenceable as u8 arrays (we recommend [u8; N] for some N).

fn from_seed(seed: Self::Seed) -> Self

Create a new PRNG using the given seed.

fn seed_from_u64(seed: u64) -> Self

Create a new PRNG using a u64 seed.

fn from_rng<S: RngCore>(rng: S) -> Result<Self, Error>

Create a new PRNG seeded from another Rng.

fn from_entropy() -> Self

Creates a new instance of the RNG seeded via getrandom.