Module bitstream 

Bit-level stream writers for zstd encoding.

BitWriter — forward bitstream (Huffman literals). BackwardBitWriter — backward bitstream (FSE sequences, FSE weights).

The backward bitstream matches C zstd’s BIT_CStream_t exactly:

• Bits accumulate LSB-first in a 64-bit register
• flush_bits() writes full bytes to output (forward/LE)
• finish() adds sentinel 1-bit, flushes, returns bytes
• Decoder reads this from the END toward the BEGINNING

Structs

BackwardBitWriter

Backward bitstream writer matching C zstd’s BIT_CStream_t.

BitWriter

Forward bitstream writer (Huffman literal streams).