v2.65.4 — Sprint 134: fix broken amalgamation build + complete the reference decoders
Two correctness fixes to build and test infrastructure. The shipping
codec and wire format are unchanged.
Amalgamation (single-file build) was broken. The make amalg and
make amalg-verify recipes carried a hardcoded source/header list that
was never updated when the BCJ branch filter (vv_bcj.c / vv_bcj.h)
became a core source in v2.60.x. Since vv_compress calls
vv_bcj_detect / vv_bcj_x86 / vv_bcj_arm64 and uses
vv_filter_kind_t, the amalgamated build/vaptvupt.c failed to
compile (unknown type name 'vv_filter_kind_t', implicit-declaration
errors). The single-file build is a documented feature; both recipes
now include include/vv_bcj.h and src/vv_bcj.c. Verified: the
amalgamation compiles clean under -Wall -Wextra and round-trips all
three modes plus the --auto-filter BCJ path byte-exact.
Reference decoders now cover the default literal format. The Python
(reference/vv_huffman.py, reference/vv_ans.py) and JavaScript
(reference/vv_decoder.js) reference decoders raised
NotImplementedError on lit_fmt = 4 (HUFFMAN4, the 4-stream
interleaved Huffman format the encoder selects by default for blocks
with ≥1024 literals since v2.47.0). They therefore could not decode
typical modern output, and the differential fuzzer silently skipped
those cases — the independent cross-check did not cover the default
format. Both decoders now implement vvh_decode4 per FORMAT.md §3.4.1
(shared code table, 9-byte stream-size header, byte-aligned streams,
round-robin symbol interleave), reusing each implementation's existing
Huffman primitives. Validated byte-exact: both reference decoders
decode the full 11-file benchmark corpus in balanced and extreme mode
(22/22 each), independently confirming the C decoder on the default
format. The README's "byte-exact reference decoders … cross-check C
against Python" is now accurate for the default format.
Validation: 22/22 C test suites under -O3 -flto and under
-fsanitize=address,undefined -fno-sanitize-recover=all; ratio gate
±0 (C unchanged); 5,200 differential fuzz cases consistent; JS
reference suite 17/17; both reference decoders byte-exact on the corpus.