A third entropy coder peer alongside [`crate::entropy::huffman`] and [`crate::entropy::rans`]. Where Huffman wastes the fractional bits that integer code lengths can't represent, tANS — like rANS — codes at (near-)entropy cost; the *tabled* variant does it with a single table lookup per symbol on both encode and decode, the construction Zstd uses internally (FSE). See the 2024 ANS survey (<https://arxiv.org/abs/2408.07322>) for the modern treatment. ## Design Single-stream, byte-alphabet, with an 11-bit normalized frequency table (`TABLE_LOG = 11`, `L = 2048`) to match rANS's precision. The coder is the textbook tANS with an explicit fixed start state, which keeps the encode/decode bit accounting exactly symmetric (`n` encode transitions ↔ `n` decode transitions, one flush ↔ one init) and sidesteps the asymmetric first-symbol initialization micro-optimization that the Zstd/FSE reference uses. The decoder recovers the start state and verifies the bitstream is fully consumed, so a corrupt payload fails rather than producing garbage. 4-stream interleaving (the shared `stream_frame` framing the Huffman / rANS coders use for parallel decode) is a deliberate follow-up — this single-stream form is a complete, correct dispatcher peer. ## Blob layout (what [`compress`] writes / [`decompress`] reads) ```text [ table_log : u8 ] [ nsym : u16 LE ] number of symbols with freq > 0 nsym × [ sym : u8 ][ freq : u16 LE ] normalized frequencies (sum = 2^table_log) [ total_bits : u64 LE ] length of the FSE bitstream in bits [ bitstream : ⌈total_bits / 8⌉ bytes ] ```