Struct RansDecoder 

pub struct RansDecoder<'a> { /* private fields */ }

A symbol-at-a-time rANS decoder.

Constructed from a byte stream produced by RansEncoder::finish or encode. Decode symbols with get, or use the bits-back primitives peek + advance.

Implementations

impl<'a> RansDecoder<'a>

pub fn new(bytes: &'a [u8]) -> Result<Self, AnsError>

Initialize a decoder from an encoded byte stream.

Returns an error if the stream is too short (< 4 bytes) or the initial state is below RANS_L.

pub fn get(&mut self, table: &FrequencyTable) -> Result<u32, AnsError>

Decode a single symbol from the rANS state.

Equivalent to calling peek followed by advance.

pub fn peek(&self, table: &FrequencyTable) -> u32

Peek at the next symbol without advancing the state.

Returns the symbol whose frequency interval contains the current slot. Use with advance for bits-back coding, where the caller needs the slot value before deciding how to advance.

Validity

The returned symbol is guaranteed to be in-range only when the decoder state is valid, i.e. the decoder was just constructed via new or the most recent advance call succeeded. If advance returned an error (truncated input), the state may be partially updated and peek results are undefined.

pub fn advance( &mut self, sym: u32, table: &FrequencyTable, ) -> Result<(), AnsError>

Advance the decoder state after a peek.

sym must be the symbol returned by peek (or a valid symbol whose frequency interval contains the current slot). Passing the wrong symbol will silently corrupt the state.

pub fn state(&self) -> u32

Current rANS state (for bits-back interleaving).

pub fn remaining_bytes(&self) -> usize

Number of unread bytes remaining in the buffer (excluding the initial state).

Trait Implementations

impl<'a> Debug for RansDecoder<'a>

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

Formats the value using the given formatter.