kpermute

kpermute/com.eignex.kpermute/HalfLongPermutation

HalfLongPermutation

class HalfLongPermutation(val size: Long = Long.MAX_VALUE, rng: Random = Random.Default, rounds: Int = 3, const: Long = 5955220737039975883) : LongPermutation(source)

Finite long permutation using cycle-walking over a 2^k-sized block.

Embeds the domain [0, size) in a power-of-two block and applies reversible affine steps plus XOR-shift mixing. Outputs outside [0, size) are rejected and walked until they fall back inside the domain.

Parameters

rng

Random generator used to derive per-round keys.

rounds

Number of mixing rounds; higher values increase dispersion.

const

Odd multiplicative constant used in each affine step.

Constructors

HalfLongPermutation

constructor(size: Long = Long.MAX_VALUE, rng: Random = Random.Default, rounds: Int = 3, const: Long = 5955220737039975883)

Properties

open override val size: Long

Size of the permutation domain; valid inputs are [0, size).

Functions

open fun decode(encoded: Long): Long

Decodes a previously encoded long back to its original value.

decodeUnchecked

open override fun decodeUnchecked(encoded: Long): Long

Decodes a previously encoded value without range checks.

open fun encode(value: Long): Long

Encodes a long in the permutation domain into its permuted value.

encodeUnchecked

open override fun encodeUnchecked(value: Long): Long

Encodes a value without range checks.

open override fun iterator(offset: Long): LongIterator

Returns an iterator over encode(i) for indices in [offset, size).

open operator override fun iterator(): LongIterator

Returns an iterator over encode(i) for all i in [0, size) for finite domains, or over the full 64-bit space when size == -1L.

fun LongPermutation.range(range: LongRange): LongPermutation

Returns a view of this permutation that operates on range instead of [0, size). Only valid for finite domains where range.count() == size.

open override fun toString(): String

HalfLongPermutation

constructor(size: Long = Long.MAX_VALUE, rng: Random = Random.Default, rounds: Int = 3, const: Long = 5955220737039975883)(source)

Parameters

rng

Random generator used to derive per-round keys.

rounds

Number of mixing rounds; higher values increase dispersion.

const

Odd multiplicative constant used in each affine step.

decodeUnchecked

open override fun decodeUnchecked(encoded: Long): Long(source)

Decodes a previously encoded value without range checks.

encodeUnchecked

open override fun encodeUnchecked(value: Long): Long(source)

Encodes a value without range checks.

iterator

open override fun iterator(offset: Long): LongIterator(source)

Returns an iterator over encode(i) for indices in [offset, size).

For finite domains, offset is an index in 0..size. For full-domain implementations, semantics are defined by the implementation.

size

open override val size: Long(source)

toString

open override fun toString(): String(source)