Struct ANSEncodingHistogram 

pub struct ANSEncodingHistogram {
    pub counts: Vec<i32>,
    pub alphabet_size: usize,
    pub cost: f32,
    pub method: u32,
    pub omit_pos: usize,
    /* private fields */
}

Normalized ANS histogram for encoding.

Contains frequency counts normalized to sum to ANS_TAB_SIZE (4096).

Fields

counts: Vec<i32>

Normalized frequency counts.

alphabet_size: usize

Alphabet size (highest non-zero symbol + 1).

cost: f32

Cost estimate (header + data bits).

method: u32

Encoding method:

• 0: flat distribution
• 1: small code (1-2 symbols)
• 2-13: shift value + 1

omit_pos: usize

Position of the balancing bin (absorbs rounding error).

Implementations

impl ANSEncodingHistogram

pub fn new() -> Self

Create an empty histogram.

pub fn from_histogram( histo: &Histogram, strategy: ANSHistogramStrategy, ) -> Result<Self>

Create from a Histogram with the best normalization.

Tries different shift values and picks the one with lowest cost. Use from_histogram_cached with a precomputed AllowedCountsCache when calling this in a loop to avoid repeated table construction.

pub fn from_histogram_cached( histo: &Histogram, strategy: ANSHistogramStrategy, cache: &AllowedCountsCache, ) -> Result<Self>

Create from a Histogram using precomputed allowed counts tables.

This is the fast path — call AllowedCountsCache::new() once and reuse it across all histogram normalization calls to avoid repeated allocation and sorting of allowed counts tables.

pub fn write(&self, writer: &mut BitWriter) -> Result<()>

Write this histogram to a BitWriter.

Trait Implementations

impl Clone for ANSEncodingHistogram

fn clone(&self) -> ANSEncodingHistogram

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ANSEncodingHistogram

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

Formats the value using the given formatter.

impl Default for ANSEncodingHistogram

fn default() -> Self

Returns the “default value” for a type.