nx_lzma_lib.nx

nx_lzma_lib.nx -- THE LZMA AND LZMA2 DECODER (/compare/modding MD29, 2026-09-06), written from the mirrored specification (knowledge/fetched/cmp_modding_lzma-specification.txt, Igor Pavlov 2015-06-14, pin 6a4d441c) and the LZMA2 chunk rules of the public-domain SDK decoder (cmp_modding_Lzma2Dec.c, pin 41303267), both READ before a line of this was written. It is the decode-to-one-buffer variant the specification names: the OUTPUT BUFFER IS THE SLIDING WINDOW, so a match at distance d reads out[pos - d] and a dictionary reset simply moves the base the distance check measures from. The probability counters are i64 slots (11-bit values), the range coder keeps Range and Code as 32-bit values inside i64 (masked after every shift, exactly as the specification's note on wider integers requires), and every corruption the specification lets the reference decoder IGNORE is likewise ignored here so the output matches the reference byte for byte; the conditions the specification calls errors (distance past the window or dictionary, a literal past the unpack size, a match longer than what remains, a non-zero first byte, a marker with a non-zero code) are REFUSALS, named by code. LZMA2 (the 7z and xz container coder): a control byte per chunk -- 0 ends the stream; 1 and 2 copy an uncompressed chunk (1 resets the dictionary); 0x80 and above carry an LZMA chunk whose low five bits are the unpack size's high bits, then two big-endian bytes each of unpack size minus one and pack size minus one, then a properties byte when bit 6 is set; bits 5 and 6 select the reset: 0 nothing, 1 state, 2 state plus new properties, 3 state plus properties plus dictionary. Every LZMA chunk re-initialises the range coder from its own first five bytes (the SDK sets needFlush on every chunk). license_tier: ORIGINAL No hw writes (Rule 26).