Struct rand::prng::isaac::IsaacCore[][src]

pub struct IsaacCore { /* fields omitted */ }

The core of IsaacRng, used with BlockRng.

Trait Implementations

impl Clone for IsaacCore
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Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

impl Debug for IsaacCore
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Formats the value using the given formatter. Read more

impl BlockRngCore for IsaacCore
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Results element type, e.g. u32.

Results type. This is the 'block' an RNG implementing BlockRngCore generates, which will usually be an array like [u32; 16]. Read more

Refills the output buffer, results. See also the pseudocode desciption of the algorithm in the IsaacRng documentation.

Optimisations used (similar to the reference implementation):

  • The loop is unrolled 4 times, once for every constant of mix().
  • The contents of the main loop are moved to a function rngstep, to reduce code duplication.
  • We use local variables for a and b, which helps with optimisations.
  • We split the main loop in two, one that operates over 0..128 and one over 128..256. This way we can optimise out the addition and modulus from s[i+128 mod 256].
  • We maintain one index i and add m or m2 as base (m2 for the s[i+128 mod 256]), relying on the optimizer to turn it into pointer arithmetic.
  • We fill results backwards. The reference implementation reads values from results in reverse. We read them in the normal direction, to make fill_bytes a memcopy. To maintain compatibility we fill in reverse.

impl SeedableRng for IsaacCore
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Seed type, which is restricted to types mutably-dereferencable as u8 arrays (we recommend [u8; N] for some N). Read more

Create a new PRNG using the given seed. Read more

Create a new PRNG seeded from another Rng. Read more

Create a new PRNG using a u64 seed. Read more

Auto Trait Implementations

impl Send for IsaacCore

impl Sync for IsaacCore