Struct AnsDistribution 

pub struct AnsDistribution {
    pub symbols: Vec<AnsEncSymbolInfo>,
    pub log_alpha_size: u32,
    pub total: u32,
}

A complete ANS distribution with encoding info for all symbols.

Fields

symbols: Vec<AnsEncSymbolInfo>

Symbol encoding information.

log_alpha_size: u32

Log2 of distribution size (typically 12).

total: u32

Total of normalized frequencies (should be ANS_TAB_SIZE).

Implementations

impl AnsDistribution

pub fn from_frequencies(freqs: &[u32]) -> Result<Self>

Creates a distribution from raw frequencies.

Normalizes frequencies to sum to ANS_TAB_SIZE.

pub fn flat(alphabet_size: usize) -> Result<Self>

Creates a flat (uniform) distribution.

pub fn from_normalized_counts(counts: &[i32]) -> Result<Self>

Creates a distribution from pre-normalized counts.

The counts must already sum to ANS_TAB_SIZE (4096). This is used when building distributions from ANSEncodingHistogram which has already done the normalization.

pub fn from_normalized_counts_with_log_alpha( counts: &[i32], log_alpha_size: usize, ) -> Result<Self>

Creates a distribution from pre-normalized counts with explicit log_alpha_size.

Use this when multiple distributions share a single header (e.g., multi-histogram ANS). The log_alpha_size must match the value written to the bitstream header, NOT the per-distribution default. The decoder reads one global log_alpha_size and uses it for all distributions in the group.

pub fn alphabet_size(&self) -> usize

Returns the number of symbols in this distribution.

pub fn get(&self, symbol: usize) -> Option<&AnsEncSymbolInfo>

Gets the encoding info for a symbol.

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

Writes this distribution to a BitWriter.

Trait Implementations

impl Clone for AnsDistribution

fn clone(&self) -> AnsDistribution

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AnsDistribution

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

Formats the value using the given formatter.