`std/compression`

Compressed bytes: DEFLATE (RFC 1951) with deflated and inflated, gzip (RFC 1952) around it with gzipped and gunzipped, and the crc32 gzip checks a member with. What a package archive of the registry is compressed with (docs/design/RELEASE.md section 7.2), and what an HTTP body with Content-Encoding: gzip is.

Ordinary TorbScript over List<UInt8>, with no native. Inflating reads every stream the format allows - stored, fixed and dynamic blocks, and gzip members one after the other. Deflating is deterministic and simple: one block of the fixed codes, with a greedy match search over the last 32 KiB. It compresses text to roughly half, where zlib's dynamic codes get to a third; what it writes is the same for the same bytes on every machine, which is what a reproducible archive needs, and any inflater reads it.

Modules

std/compression/crc[crc32]: the checksum of gzip, zip and PNG.
std/compression/deflate[deflated]: DEFLATE written (RFC 1951) as one block of the fixed codes.
std/compression/error[CompressionError]: what reading compressed bytes fails with.
std/compression/gzip[gzipped] and [gunzipped]: gzip members (RFC 1952) around DEFLATE.
std/compression/inflate[inflated]: DEFLATE read back (RFC 1951), after Mark Adler's puff.c - canonical Huffman codes decoded one bit at a time, which is short and exact rather than fast.

Everything

type CompressionErrorCompressed bytes that break their format: what is wrong, and the byte of the input where it was found.
extend CompressionError with From<ReadError>A read of std/binary that ran out of compressed bytes.
fn crc32The CRC-32 of ISO 3309 and ITU-T V.42 - the reflected polynomial 0xEDB88320 - of bytes.
fn deflatedbytes as a raw DEFLATE stream: one final block of the fixed Huffman codes.
fn gunzippedWhat every gzip member of bytes holds, one after the other.
fn gzippedbytes as one gzip member, with nothing in its header that depends on the machine or the moment: no file name, no time, the operating system "unknown".
fn inflatedEverything a raw DEFLATE stream holds, which has to end with its last block.