Struct BackwardBitWriter 

pub struct BackwardBitWriter { /* private fields */ }

Backward bitstream writer for FSE sequence encoding.

Produces a byte array compatible with the FseBitReader:

• The last byte contains a sentinel (highest set bit) and the first data bits.
• Preceding bytes contain subsequent data bits, with byte at index N-2 being read after the sentinel byte, N-3 after that, etc.

The encoder writes bits in the same order the decoder reads them (first written = first decoded).

Internally, bits are accumulated into a Vec<u8> from MSB of the highest byte down to LSB of byte 0. At finish(), a sentinel is added and the output is ready for the decoder.

Implementations

impl BackwardBitWriter

pub fn new() -> Self

Create a new backward bitstream writer.

pub fn with_capacity(byte_capacity: usize) -> Self

Create a new backward bitstream writer with a capacity hint.

pub fn write_bits(&mut self, value: u64, num_bits: u8)

Write num_bits bits from value into the backward stream.

The lowest num_bits bits of value are appended. The first call’s bits will be the first bits the decoder reads.

pub fn write_bit(&mut self, bit: bool)

Write a single bit (0 or 1).

pub fn finish(self) -> Vec<u8>

Finalize the backward bitstream.

Produces a byte array where:

• The last byte contains the sentinel and the first data bits.
• Preceding bytes (read from index N-2 down to 0) contain later data bits.

The FseBitReader loads the sentinel byte’s data bits first (into the accumulator’s LSB), then loads byte N-2, N-3, …, 0 into successively higher accumulator positions.

Returns the finalized byte vector. If no bits were written, returns [0x01].

pub fn len(&self) -> usize

Number of data bits written so far (excludes sentinel).

pub fn is_empty(&self) -> bool

Whether no bits have been written yet.

Trait Implementations

impl Default for BackwardBitWriter

fn default() -> Self

Returns the “default value” for a type.