nx_rans.nx

nx_rans.nx -- SOVEREIGN, PATENT-FREE static-frequency rANS entropy coder. The keystone of the patent-free video-codec arc (project-sovereign-patent-free-codec-2026-06-20). rANS = the range variant of Asymmetric Numeral Systems (J. Duda, dedicated to the PUBLIC DOMAIN; the USPTO rejected Google's attempt to patent ANS use, 2018). This is PLAIN static-frequency rANS -- explicitly NOT the Petagene Markov+escape-code variant (US9847791B2) and NOT the Microsoft two-phase / switchable-width / fragment-flush hardware variant (US11234023B2) -- so it reads on no active claim (deep-research verified 2026-06-20). Byte-oriented, 32-bit state in the ryg style (RANS_L = 1<<23, 8-bit renormalization), SCALE_BITS supplied by the caller (12 = a 4096-entry table). LOSSLESS: rans_decode(rans_encode(x)) == x, bit-exact -- the COMPLETE correctness criterion for an entropy stage whose encoder AND decoder we both own (no external interop, so round-trip self-proof is sufficient and total). license_tier: ORIGINAL