Move FSE normalization, count-header writing, compression-table construction,
and stream encoding from C to Rust. The original C source remains as a
header-only shim, preserving the public header configuration while native
consumers receive the Rust archive exports.
This completes both codec directions for FSE in the migration crate and lets
the unchanged C compatibility tests exercise the Rust encoder implementation.
Test Plan:
- cargo clippy; cargo clippy --benches; cargo clippy --tests
- cargo +nightly fmt, then repeat the Clippy checks
- cargo test --all-targets
- cargo build --release
- Compile the C shim with strict warnings enabled
- 1,000-case pristine-C differential for tables, headers, and payloads
- ./tests/fuzzer -v -T10s
- ./tests/decodecorpus -t -T5
Refs: rust/README.md
Make Rust sources normal prerequisites of native C test executables and CLI
builds. A changed Rust module now rebuilds libzstd_rs.a and relinks the target,
instead of relying on a manually prepared archive that can silently be stale.
The archive is linked after C objects, allowing migrated C shims to resolve
their Rust ABI symbols while remaining compatible with the existing makefile
flows. The migration guide now documents this behavior.
Test Plan:
- make -B -C tests fuzzer
- ./tests/fuzzer -i1 --no-big-tests
- make -B -C programs zstd
- ./programs/zstd --version
Refs: rust/README.md
Keep local Rust build outputs out of the migration diff. The static archive is
rebuilt by the validation workflow and must not be tracked as source.
Test Plan:
- git check-ignore -v rust/target
Refs: rust/README.md
Move byte histogram counting into Rust for FSE and Huffman compression callers.
The implementation preserves the C workspace contract, checked alphabet path,
fast path, empty-input behavior, and C ABI while the original C source becomes
a header-only compatibility shim.
Focused tests cover count accumulation, invalid alphabets, workspace failures,
and striped large inputs. Higher-level compression remains C for now.
Test Plan:
- cargo fmt --check
- cargo test --all-targets
- cargo clippy --all-targets -- -D warnings
- cargo build --release
- make -C tests fuzzer
- ./tests/fuzzer -i1 --no-big-tests
- compile hist.c with -Werror and -Wredundant-decls
Refs: rust/README.md
Replace the common worker pool and debug pthread wrappers with ABI-compatible
Rust implementations. The pool preserves bounded-queue, resize, drain-on-free,
custom-allocator, and no-thread behavior while C supplies only the build-time
multithreading configuration bit.
This moves runtime support without changing C tests or public headers. Codec
and CLI implementations remain C while their dependencies are migrated.
Test Plan:
- cargo fmt --check
- cargo test --all-targets
- cargo clippy --all-targets -- -D warnings
- cargo build --release
- make -C tests poolTests
- ./tests/poolTests
- compile pool and threading shims with -Werror in MT and no-thread modes
Refs: rust/README.md
Move FSE normalized-count parsing, Huffman statistics decoding, FSE table
construction, and FSE stream decompression into Rust. The C source files now
only retain the headers needed by the existing build configuration.
The implementation keeps the public C ABI and verifies C-generated balanced,
skewed, and Huffman-statistics streams. Compression and the higher-level frame
decoder remain C for now.
Test Plan:
- cargo fmt --check
- cargo test --all-targets
- cargo clippy --all-targets -- -D warnings
- cargo build --release
- compile both C shims with -Werror and -Wredundant-decls
Refs: rust/README.md
The common C shims include headers that already declare every Rust-exported
symbol. Remove duplicate declarations so strict C builds do not report
redundant declarations or macro-expanded aliases.
The shims remain intentionally declaration-only; Rust still owns the exported
implementation.
Test Plan:
- compile debug.c with -Wall -Wextra -Werror
- compile error_private.c with -Wall -Wextra -Werror
- compile zstd_common.c with -Wall -Wextra -Werror
Refs: rust/README.md
Introduce the Rust static library and move the shared byte, bitstream, CPU,
error, xxHash, debug, and public-common implementations into it. Thin C shims
preserve the existing header-driven C build while original tests link the Rust
archive.
This establishes the ABI-safe foundation for later codec and CLI ports;
entropy coding, runtime support, codecs, dictionaries, and the CLI remain C.
The top-down migration map documents that boundary and its validation path.
Test Plan:
- cargo fmt --check
- cargo test --all-targets
- cargo clippy --all-targets -- -D warnings
- cargo build --release
Refs: rust/README.md
this ABI is no longer supported by Ubuntu,
and there is a wider consensus that this ABI is on the way out,
with more and more distributions dropping it,
and lingering questions about support of x32 in the kernel.
the purpose of --ultra is to make the user explicitly opt-in
to generate very large window size (> 8 MB).
The agreement to generate very large window size is already implicit
when selecting --long or --patch-from.
Consequently, `--ultra ` is automatically enabled when `--long` or `--patch-from` is set.
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