format: ZFP decoder (filter 32013), pure Rust, read-only

A port of the zfp 1.0.1 decoder and of H5Z-ZFP 1.1.1's decompression
path behind a new `zfp` feature (in `plugin-filters`): every mode
(fixed rate, precision, accuracy, reversible, expert), int32, int64,
float and double, 1-4 dimensional fields with partial blocks, and
headers written big-endian (values byte-swapped as H5Z-ZFP does).

H5Z-ZFP keeps the zfp header in cd_values (version word, then the
magic/metadata/mode bit stream); each chunk is the bare stream. The
decoder reproduces libzfp bit for bit: integer arithmetic wraps as
libzfp's, block exponents scale by exact powers of two, and the mode
goes through zfp_stream_mode as H5Z-ZFP hands it to zfp. A stream that
ends early is an error (libzfp reads past its buffer), as is a field
whose size is not the chunk's; the output is allocated only once the
stream holds a bit per block.

Tests: header/mode unit tests, and a counting-allocator fuzz of random
headers (expert parameters at their edges) and streams.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

crates/clawhdf5-format/Cargo.toml

@@ -78,8 +78,11 @@ bzip2 = ["dep:bzip2", "std"]
 blosc = ["lz4_flex", "ruzstd", "snap", "deflate", "std"]
 # Blosc2 (32026), read-only: frames, B2ND arrays, and the Blosc codecs above.
 blosc2 = ["blosc"]
+# ZFP (32013, H5Z-ZFP), read-only: every mode, for int32, int64, float and
+# double fields of 1 to 4 dimensions.
+zfp = []
 # Every plugin filter above.
-plugin-filters = ["lzf", "bitshuffle", "bzip2", "blosc", "blosc2"]
+plugin-filters = ["lzf", "bitshuffle", "bzip2", "blosc", "blosc2", "zfp"]
 
 [[bench]]
 name = "parallel_decompress_bench"