# gizlang:compress

DEFLATE (RFC 1951), gzip (RFC 1952) and CRC checksums, written in Gizlang. deflate finds repeats greedily in a two-way hash table of 4-byte prefixes over a 32 KB window (tokenize), counts the symbols, and writes one block with Huffman codes built for them (dynamic) or DEFLATE's fixed codes, whichever is shorter. Both are canonical codes from lengths, built by the same functions. The tables are constant Vec literals. The checksums run in the runtime (gizlang_crc32_update), on the CPU's CRC instructions.

```gizlang
import * as Compress from "gizlang:compress";
```

## Types

### `Crc32`

```gizlang
type Crc32 = { state: u64; }
```

The state of a running CRC-32.

- `state`: `u64`

### `Crc32c`

```gizlang
type Crc32c = { state: u64; }
```

Castagnoli CRC-32C uses a different polynomial from gzip's IEEE CRC-32: the SSE4.2 CRC32 instruction where the
CPU has it, else slicing-by-8.

- `state`: `u64`

### `Deflater`

```gizlang
type Deflater
```

A streaming DEFLATE encoder in one framing (RAW, ZLIB or GZIP): write input, flush when a reader must see it
now (SYNC_FLUSH ends the block and aligns, as zlib does), finish once at the end, and take the output with read.
Each block is coded on its own (block), so a flush costs the repeats across it. Level 0 stores the data.

Opaque: create and use it through this module's functions.

### `DecodeError`

```gizlang
type DecodeError = { code: i64; offset: i64; message: string; }
```

Why a decoder stopped: code is one of the constants below, offset is the
input byte where the decoder found the problem, message tells what it is.

- `code`: `i64`
- `offset`: `i64`
- `message`: `string`

### `Inflater`

```gizlang
type Inflater
```

A streaming DEFLATE decoder: give it input with write and close, and take
the output with read; or call feed for each piece and finish at the end.

Opaque: create and use it through this module's functions.

### `Xxh64`

```gizlang
type Xxh64
```

XXH64 over data given in pieces, as zstd checks a frame: four lanes of 8
bytes, and the bytes of the last partial stripe waiting in pending.

Opaque: create and use it through this module's functions.

### `ZstdDecoder`

```gizlang
type ZstdDecoder
```

A streaming Zstandard decoder: give it input with write and close, and
take the output with read; or call feed for each piece and finish at the end. It decodes each frame of the input, and skips
skippable frames.

Opaque: create and use it through this module's functions.

### `TarMember`

```gizlang
type TarMember = { path: string; kind: string; mode: i64; data: bytes; link: string; }
```

One archive member. `kind` is "file", "directory", "symlink", "hardlink" or "other" (devices and FIFOs); `link` is
the target of a link.

- `path`: `string`
- `kind`: `string`
- `mode`: `i64`
- `data`: `bytes`
- `link`: `string`

### `BrotliEncoder`

```gizlang
type BrotliEncoder
```

A Brotli encoder: write(data) takes input, operate(op) runs PROCESS/FLUSH/FINISH, read() gives what came out.

Opaque: create and use it through this module's functions.

### `BrotliDecoder`

```gizlang
type BrotliDecoder
```

A Brotli decoder: write(data) decodes what it can; an error is libbrotli's message.

Opaque: create and use it through this module's functions.

### `Alp`

```gizlang
type Alp = { exponent: i64; digits: Vec<i64>; at: Vec<i64>; exceptions: Vec<f64>; }
```

A vector of doubles as ALP integers: `digits[i]` / 10^`exponent`, except at the positions `at`, whose values are
`exceptions`.

- `exponent`: `i64`
- `digits`: `Vec<i64>`
- `at`: `Vec<i64>`
- `exceptions`: `Vec<f64>`

### `ZipWriter`

```gizlang
type ZipWriter
```

A zip archive, written in order: the caller writes what each call returns. An entry comes whole (`file`: its bytes
stored or deflated, its CRC and sizes in its header) or as it streams (`entry`, then `data` for each piece of its
bytes, which the caller writes as they are, then a data descriptor). A streamed entry is stored: most bytes people
keep are compressed already, and storing keeps the archive at disk speed. Names are UTF-8 (flag bit 11 when a name is
not ASCII). A modified time goes as a DOS time and as UTC seconds (extra 0x5455); modified 0 writes no time
(1980-01-01 and no extra field), as the first entry of an OCF container needs. ZIP64 records come in only where a
size, an offset or the count needs them. `finish` writes the central directory.

Opaque: create and use it through this module's functions.

### `ZipEntry`

```gizlang
type ZipEntry = { name: string; size: i64; stored: i64; method: u64; crc: u64; modified: i64; offset: i64; }
```

One entry of a zip archive, as its central directory records it: NAME (a folder's ends in "/"), SIZE bytes, STORED
of them in the archive by METHOD (0 stored, 8 deflated), their CRC, MODIFIED (ms since 1970: extra 0x5455's UTC
seconds, else the DOS time read as UTC, 0 for none) and OFFSET, where its local header is.

- `name`: `string`
- `size`: `i64`
- `stored`: `i64`
- `method`: `u64`
- `crc`: `u64`
- `modified`: `i64`
- `offset`: `i64`

## Functions

### `crc32`

```gizlang
function crc32(data: bytes): u64
```

The CRC-32 of data, as gzip and zip record it.

Effects: fail.

### `newCrc32`

```gizlang
function newCrc32(): Crc32
```

A CRC-32 checksum (the one of zlib, gzip and zip) of no data.

### `crc32Combine`

```gizlang
function crc32Combine(first: u64, second: u64, secondBytes: i64): u64 requires secondBytes> = 0 { let factor = CRC32_TOP_BIT
```

CRC-32 of concatenated regions from their digests and the second length,
without joining or rereading their buffers.

Effects: fail.

### `newCrc32c`

```gizlang
function newCrc32c(): Crc32c
```

A CRC-32C (Castagnoli) checksum of no data.

### `crc32c`

```gizlang
function crc32c(data: bytes): u64
```

The CRC-32C checksum of DATA.

Effects: fail.

### `crc16Xmodem`

```gizlang
function crc16Xmodem(data: bytes): u64
```

CRC-16/XMODEM: polynomial 0x1021, initial zero, no reflection or final xor.

Effects: fail.

### `lz4`

```gizlang
function lz4(data: bytes): bytes
```

DATA as one LZ4 block (the LZ4 block format, no frame): greedy matches of 4 or more bytes within 64 KB, found in
one table of 4-byte prefixes (hash4, common). It is fast, not small: for bytes that are written and read often.
A run of misses makes the search step longer, so data that does not compress costs little.

Effects: fail.

### `unlz4`

```gizlang
function unlz4(block: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { let out = b""
```

The data of the LZ4 block BLOCK, at most LIMIT bytes of output.

Effects: fail.

### `deflate`

```gizlang
function deflate(data: bytes): bytes
```

data as one DEFLATE stream (no header): a single final block.

Effects: fail.

### `gzip`

```gizlang
function gzip(data: bytes): bytes
```

data as a gzip member: header, DEFLATE stream, CRC-32 and length.

Effects: fail.

### `newDeflater`

```gizlang
function newDeflater(framing: i64, level: i64): Deflater requires framing> = RAW && framing <= GZIP
```

A Deflate compressor at LEVEL (0 to 9) with FRAMING: RAW, ZLIB or GZIP.

Effects: fail.

### `adler32`

```gizlang
function adler32(data: bytes): u64
```

The Adler-32 checksum of data (RFC 1950), as zlib records it.

Effects: fail.

### `newInflater`

```gizlang
function newInflater(framing: i64, limit: i64): Inflater requires framing> = RAW && framing <= GZIP requires limit> = 0 { let state = I_HEADER
```

A decoder for one framing (RAW, ZLIB or GZIP) that refuses more than limit
bytes of output. GZIP decodes each member of a multi-member file.

Effects: fail.

### `inflater`

```gizlang
function inflater(framing: i64): Inflater requires framing> = RAW && framing <= GZIP
```

A decoder of framing RAW, ZLIB or GZIP with no output limit, for feed and finish.

Effects: fail.

### `inflate`

```gizlang
function inflate(data: bytes, framing: i64, limit: i64): bytes throws DecodeError requires framing> = RAW && framing <= GZIP requires limit> = 0 { let d = new Inflater(framing, limit)
```

The DEFLATE stream data decoded (framing RAW, ZLIB or GZIP), at most limit bytes of output.

Effects: fail.

### `gunzip`

```gizlang
function gunzip(data: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { return inflate(data, GZIP, limit)
```

The gzip file data decoded (every member), at most limit bytes of output.

Effects: fail.

### `newXxh64`

```gizlang
function newXxh64(seed: u64): Xxh64
```

A new XXH64 hash state with SEED.

### `xxh64`

```gizlang
function xxh64(data: bytes, seed: u64): u64
```

The XXH64 of data with a seed.

Effects: fail.

### `newZstdDecoder`

```gizlang
function newZstdDecoder(limit: i64, windowLimit: i64): ZstdDecoder requires limit> = 0 && windowLimit> = 0 { return { _limit: limit, _windowLimit: windowLimit, _input: b"", _at: 0, _base: 0, _ended: false, _end: 0, _state: Z_MAGIC, _skip: 0, _frames: 0, _window: 0, _fcs: -1, _frameOut: 0, _hasChecksum: false, _blockMax: 0, _buf: b"", _pos: 0, _start: 0, _floor: 0, _produced: 0, _hash: new Xxh64(0u), _lits: filled(ZSTD_BLOCK + 64, 0u), _tables: noEntropy(), _dictTables: noEntropy(), _dict: b"", _dictId: 0, _llDefault: fseTable(literalLengthDefault(), 6, FSE_LITERALS), _mlDefault: fseTable(matchLengthDefault(), 6, FSE_MATCHES), _ofDefault: fseTable(offsetDefault(), 5, FSE_OFFSETS), _error: 0, _errorAt: 0, _message: "", }
```

A decoder that refuses more than limit bytes of output and frames with a
window over windowLimit bytes (ZSTD_WINDOW_LIMIT is the zstd tool's). Its
memory is about twice the window of the frame, and no more than the limit.

Effects: fail.

### `zstdDecoder`

```gizlang
function zstdDecoder(): ZstdDecoder
```

A decoder with no output limit and windows up to ZSTD_WINDOW_LIMIT, for feed and finish.

Effects: fail.

### `unzstd`

```gizlang
function unzstd(data: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { let d = new ZstdDecoder(limit, ZSTD_WINDOW_LIMIT)
```

The Zstandard data decoded (every frame), at most limit bytes of output,
with windows up to ZSTD_WINDOW_LIMIT.

Effects: fail.

### `unzstdWith`

```gizlang
function unzstdWith(data: bytes, dictionary: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { let d = new ZstdDecoder(limit, ZSTD_WINDOW_LIMIT)
```

unzstd with a dictionary (see useDictionary).

Effects: fail.

### `untar`

```gizlang
function untar(archive: bytes, limit: i64): Vec<TarMember> throws DecodeError requires limit> = 0 { let members: Vec<TarMember> = []
```

Every member of `archive` in order, with pax and GNU long-name headers applied to the member after them. It reads the
archive as given: the caller decides which members to keep. It fails (CORRUPT) on a header whose checksum is wrong or
whose data runs past the archive, and (TOO_LARGE) when the members hold more than `limit` bytes (their bodies and
the pax and long-name records).

Effects: fail.

### `tarPadding`

```gizlang
function tarPadding(size: i64): i64
```

The zero bytes after a member body of `size` bytes, to the next 512-byte block.

Effects: fail.

### `tarHeader`

```gizlang
function tarHeader(path: string, mode: i64, size: i64, link: string): bytes
```

The header blocks of one member fixed by its fields alone (owner 0, time 0): a pax header when PATH or LINK is longer
than 100 bytes, then the ustar block. A member with a LINK is a hard link with no body; otherwise it is a file of SIZE
bytes, whose body and `tarPadding(size)` zero bytes follow. Two archives of the same members are the same bytes.

Effects: fail.

### `newBrotliEncoder`

```gizlang
function newBrotliEncoder(): BrotliEncoder
```

A Brotli compressor with the default parameters.

### `brotli`

```gizlang
function brotli(data: bytes, quality: i64): Result<bytes, string>
```

DATA in one Brotli stream at QUALITY with a 4 MB window (22).

Effects: fail.

### `newBrotliDecoder`

```gizlang
function newBrotliDecoder(): BrotliDecoder
```

A Brotli decompressor with the default parameters.

### `fsstEncode`

```gizlang
function fsstEncode(data: bytes): bytes
```

`data` compressed by FSST: its length (u64), the symbol table (a count, then each symbol's length and bytes) and the
codes. Sizes and contents of the input are kept exactly; fsstDecode reads it back.

Effects: fail.

### `fsstDecode`

```gizlang
function fsstDecode(data: bytes): bytes throws string
```

The bytes of an FSST-compressed block (its symbol table, then the codes).

Effects: fail.

### `fsstDecodeRanges`

```gizlang
function fsstDecodeRanges(data: bytes, from: Vec<i64>, to: Vec<i64>): bytes throws string
```

The bytes [FROM[k], TO[k]) of fsstDecode(DATA) for each k, joined: FROM ascending, the ranges apart. The codes before a range
are only counted, and decoding stops after the last range: a top-k's few rows of a block of 100K strings (ClickBench Q23).

Effects: fail.

### `alpEncode`

```gizlang
function alpEncode(v: Vec<f64>): Alp
```

The values of V in ALP form: integers at a decimal scale, with the values that do not fit kept apart.

Effects: fail.

### `alpDecode`

```gizlang
function alpDecode(a: Alp): Vec<f64> throws string
```

The doubles of `a`, or an error for an exponent or exception position out of range.

Effects: fail.

### `newZipWriter`

```gizlang
function newZipWriter(): ZipWriter
```

A writer of a zip archive in memory, with no entries.

### `zipEntries`

```gizlang
function zipEntries(size: i64, read: (at: i64, count: i64) => Result<bytes, string>, most: i64): Vec<ZipEntry> throws DecodeError
```

The first MOST entries of the zip archive of SIZE bytes that READ(at, count) reads, in their central directory's
order, ZIP64 included. It reads the end records and the central directory, never an entry's bytes. A name that is not
UTF-8 (an old archive's code page) shows each byte past ASCII as U+FFFD.

Effects: fail, read, write, console, io.

### `unzipEntry`

```gizlang
function unzipEntry(e: ZipEntry, read: (at: i64, count: i64) => Result<bytes, string>, limit: i64): bytes throws DecodeError requires limit> = 0 { if (e.size> limit) { return Result.err(DecodeError(TOO_LARGE, e.offset, `zip: ${ e.name } has ${ e.size } bytes, over the limit of ${ limit }`))
```

The bytes of entry E of the archive that READ(at, count) reads, checked against its CRC: TOO_LARGE past LIMIT bytes,
UNSUPPORTED when it is encrypted or packed by a method other than stored or deflated.

Effects: fail, read, write, console, io.

## Methods

### `Crc32.update`

```gizlang
function Crc32.update(self: mut Crc32, data: bytes): void
```

Adds DATA to the checksum.

Effects: fail.

### `Crc32.digest`

```gizlang
function Crc32.digest(self: Crc32): u64
```

The checksum of the data added so far.

Effects: fail.

### `Crc32c.update`

```gizlang
function Crc32c.update(self: mut Crc32c, data: bytes): void
```

Chunk boundaries never alter the checksum; data can remain in its current buffers.

Effects: fail.

### `Crc32c.digest`

```gizlang
function Crc32c.digest(self: Crc32c): u64
```

The checksum of the data added so far.

Effects: fail.

### `Deflater.level`

```gizlang
function Deflater.level(self: Deflater): i64
```

The compression level (0 to 9).

### `Deflater.setLevel`

```gizlang
function Deflater.setLevel(self: mut Deflater, level: i64): void
```

Sets the compression level (0 to 9) for the input that follows.

### `Deflater.finished`

```gizlang
function Deflater.finished(self: Deflater): bool
```

Whether the stream has ended (a FINISH flush is done).

### `Deflater.read`

```gizlang
function Deflater.read(self: mut Deflater): bytes
```

The output produced so far, taken.

### `Deflater.write`

```gizlang
function Deflater.write(self: mut Deflater, input: bytes): void requires!self._finished
```

Add input; whole blocks of it are coded as they fill.

Effects: fail.

### `Deflater.flush`

```gizlang
function Deflater.flush(self: mut Deflater, kind: i64): void
```

The pending input coded (KIND other than NO_FLUSH); SYNC_FLUSH and FULL_FLUSH add an empty stored block so the
output ends on a byte with all the input decodable; FINISH ends the stream with its trailer.

Effects: fail.

### `Inflater.write`

```gizlang
function Inflater.write(self: mut Inflater, input: bytes): void requires!self._ended
```

Add input. The decoder keeps only the input that it has not decoded.

Effects: fail.

### `Inflater.close`

```gizlang
function Inflater.close(self: mut Inflater): void
```

Mark the end of the input. After it, a stream that has not ended is TRUNCATED.

Effects: fail.

### `Inflater.done`

```gizlang
function Inflater.done(self: Inflater): bool
```

Whether the stream has ended and all its output was read.

### `Inflater.read`

```gizlang
function Inflater.read(self: mut Inflater): bytes throws DecodeError
```

The next output, at most 256 KiB. Empty when the decoder needs input
(write more, or close) or when it is done. An error stays: each later
read returns it again.

Effects: fail.

### `Inflater.feed`

```gizlang
function Inflater.feed(self: mut Inflater, input: bytes): bytes throws string
```

Write input and return all the output that it makes now.

Effects: fail.

### `Inflater.finish`

```gizlang
function Inflater.finish(self: mut Inflater): bytes throws string
```

End the input and return the rest of the output. A stream that has not ended is an error.

Effects: fail.

### `Xxh64.update`

```gizlang
function Xxh64.update(self: mut Xxh64, data: bytes, from: i64, to: i64): void requires from> = 0 && from <= to && to <= data.length { self._total + = to - from
```

Add the bytes from..to of data.

Effects: fail.

### `Xxh64.digest`

```gizlang
function Xxh64.digest(self: Xxh64): u64
```

The XXH64 of the bytes so far.

Effects: fail.

### `ZstdDecoder.useDictionary`

```gizlang
function ZstdDecoder.useDictionary(self: mut ZstdDecoder, dictionary: bytes): i64 throws DecodeError
```

Use a dictionary for the frames that follow: a zstd dictionary (its
entropy tables, repeat offsets and content) or, without the dictionary
magic, raw content. Its ID is what a frame names (0 for raw content).

Effects: fail.

### `ZstdDecoder.write`

```gizlang
function ZstdDecoder.write(self: mut ZstdDecoder, input: bytes): void requires!self._ended
```

Add input. The decoder keeps only the input that it has not decoded.

Effects: fail.

### `ZstdDecoder.close`

```gizlang
function ZstdDecoder.close(self: mut ZstdDecoder): void
```

Mark the end of the input. After it, a frame that has not ended is TRUNCATED.

Effects: fail.

### `ZstdDecoder.done`

```gizlang
function ZstdDecoder.done(self: ZstdDecoder): bool
```

Whether the input has ended after a whole frame, and all output was read.

### `ZstdDecoder.read`

```gizlang
function ZstdDecoder.read(self: mut ZstdDecoder): bytes throws DecodeError
```

The next output, at most 1 MiB. Empty when the decoder needs input (write
more, or close) or when it is done. An error stays: each later read
returns it again.

Effects: fail.

### `ZstdDecoder.feed`

```gizlang
function ZstdDecoder.feed(self: mut ZstdDecoder, input: bytes): bytes throws string
```

Write input and return all the output that it makes now.

Effects: fail.

### `ZstdDecoder.finish`

```gizlang
function ZstdDecoder.finish(self: mut ZstdDecoder): bytes throws string
```

End the input and return the rest of the output. A frame that has not ended is an error.

Effects: fail.

### `BrotliEncoder.setParameter`

```gizlang
function BrotliEncoder.setParameter(self: mut BrotliEncoder, param: i64, value: i64): bool
```

Sets the parameter PARAM (BROTLI_QUALITY or BROTLI_WINDOW) to VALUE; false when libbrotli refuses it.

### `BrotliEncoder.finished`

```gizlang
function BrotliEncoder.finished(self: BrotliEncoder): bool
```

Whether the stream has ended.

### `BrotliEncoder.write`

```gizlang
function BrotliEncoder.write(self: mut BrotliEncoder, input: bytes, op: i64): bool
```

INPUT compressed with OP; the output joins the pending bytes. False when libbrotli refused.

Effects: fail.

### `BrotliEncoder.read`

```gizlang
function BrotliEncoder.read(self: mut BrotliEncoder): bytes
```

The output produced so far, taken.

### `BrotliEncoder.close`

```gizlang
function BrotliEncoder.close(self: mut BrotliEncoder): void
```

Frees the compressor. It does nothing after the first call.

### `BrotliDecoder.errorCode`

```gizlang
function BrotliDecoder.errorCode(self: BrotliDecoder): i64
```

libbrotli's BrotliDecoderErrorCode of the last failed write (negative), 0 when none.

### `BrotliDecoder.setParameter`

```gizlang
function BrotliDecoder.setParameter(self: mut BrotliDecoder, param: i64, value: i64): bool
```

Sets the decoder parameter PARAM to VALUE; false when libbrotli refuses it.

### `BrotliDecoder.done`

```gizlang
function BrotliDecoder.done(self: BrotliDecoder): bool
```

Whether the stream has ended.

### `BrotliDecoder.write`

```gizlang
function BrotliDecoder.write(self: mut BrotliDecoder, input: bytes): bool throws string
```

Decompresses INPUT; the output joins the pending bytes. It fails on bad data or after close.

Effects: fail.

### `BrotliDecoder.read`

```gizlang
function BrotliDecoder.read(self: mut BrotliDecoder): bytes
```

The output produced so far, taken.

### `BrotliDecoder.close`

```gizlang
function BrotliDecoder.close(self: mut BrotliDecoder): void
```

Frees the decompressor. It does nothing after the first call.

### `ZipWriter.entry`

```gizlang
function ZipWriter.entry(self: mut ZipWriter, name: string, modified: i64): bytes
```

The local header of a streamed entry NAME (a folder ends in "/"), modified at MODIFIED (ms since 1970, 0: no time);
it ends the streamed entry before.

Effects: fail.

### `ZipWriter.data`

```gizlang
function ZipWriter.data(self: mut ZipWriter, data: bytes): void requires self._open && !self._folder
```

Counts DATA, the next bytes of the streamed entry, which the caller writes as they are.

Effects: fail.

### `ZipWriter.file`

```gizlang
function ZipWriter.file(self: mut ZipWriter, name: string, modified: i64, data: bytes, deflated: bool): bytes requires data.length <4294967295 { let out = self.closeEntry()
```

Entry NAME whole: its header and DATA, deflated when DEFLATED and that is smaller, modified at MODIFIED (ms since
1970, 0: no time). It ends the streamed entry before.

Effects: fail.

### `ZipWriter.finish`

```gizlang
function ZipWriter.finish(self: mut ZipWriter): bytes
```

The end of the archive: a streamed entry's descriptor, the central directory and the end records.

Effects: fail.

## Constants

### `NO_FLUSH`

```gizlang
const NO_FLUSH = 0
```

The flush mode no flush, 0.

### `PARTIAL_FLUSH`

```gizlang
const PARTIAL_FLUSH = 1
```

The flush mode partial flush, 1.

### `SYNC_FLUSH`

```gizlang
const SYNC_FLUSH = 2
```

The flush mode sync flush, 2.

### `FULL_FLUSH`

```gizlang
const FULL_FLUSH = 3
```

The flush mode full flush, 3.

### `FINISH`

```gizlang
const FINISH = 4
```

The flush mode finish, 4.

### `BLOCK_FLUSH`

```gizlang
const BLOCK_FLUSH = 5
```

The flush mode block flush, 5.

### `CORRUPT`

```gizlang
const CORRUPT = 1
```

The input is not a valid stream.

### `TRUNCATED`

```gizlang
const TRUNCATED = 2
```

The input ends before the stream does.

### `TOO_LARGE`

```gizlang
const TOO_LARGE = 3
```

The output, or the window that a frame asks for, is over the limit of the caller.

### `CHECKSUM`

```gizlang
const CHECKSUM = 4
```

A checksum or a recorded length does not agree with the output.

### `UNSUPPORTED`

```gizlang
const UNSUPPORTED = 5
```

The stream uses a feature that the decoder does not have (a zlib preset dictionary).

### `NEEDS_DICTIONARY`

```gizlang
const NEEDS_DICTIONARY = 6
```

The frame needs a dictionary that the decoder does not have.

### `RAW`

```gizlang
const RAW = 0
```

DEFLATE framings: no framing (RFC 1951), zlib (RFC 1950) and gzip (RFC 1952).

### `ZLIB`

```gizlang
const ZLIB = 1
```

The zlib framing (RFC 1950).

### `GZIP`

```gizlang
const GZIP = 2
```

The gzip framing (RFC 1952).

### `ZSTD_WINDOW_LIMIT`

```gizlang
const ZSTD_WINDOW_LIMIT = 134217728
```

The default window limit, as the zstd tool's (2^27).

### `BROTLI_PROCESS`

```gizlang
const BROTLI_PROCESS = 0
```

BrotliEncoderOperation.

### `BROTLI_FLUSH`

```gizlang
const BROTLI_FLUSH = 1
```

The flush mode brotli flush, 1.

### `BROTLI_FINISH`

```gizlang
const BROTLI_FINISH = 2
```

The flush mode brotli finish, 2.

### `BROTLI_QUALITY`

```gizlang
const BROTLI_QUALITY = 1
```

BrotliEncoderParameter: the quality (0 to 11) and the window (log2 of its size, 10 to 24).

### `BROTLI_WINDOW`

```gizlang
const BROTLI_WINDOW = 2
```

The parameter of the window size, as log2 of its bytes (10 to 24).

gizlang:compress

DEFLATE (RFC 1951), gzip (RFC 1952) and CRC checksums, written in Gizlang. deflate finds repeats greedily in a two-way hash table of 4-byte prefixes over a 32 KB window (tokenize), counts the symbols, and writes one block with Huffman codes built for them (dynamic) or DEFLATE's fixed codes, whichever is shorter. Both are canonical codes from lengths, built by the same functions. The tables are constant Vec literals. The checksums run in the runtime (gizlang_crc32_update), on the CPU's CRC instructions.

gizlang

import * as Compress from "gizlang:compress";

Types

`Crc32`

gizlang

type Crc32 = { state: u64; }

The state of a running CRC-32.

state: u64

`Crc32c`

gizlang

type Crc32c = { state: u64; }

Castagnoli CRC-32C uses a different polynomial from gzip's IEEE CRC-32: the SSE4.2 CRC32 instruction where the CPU has it, else slicing-by-8.

state: u64

`Deflater`

gizlang

type Deflater

A streaming DEFLATE encoder in one framing (RAW, ZLIB or GZIP): write input, flush when a reader must see it now (SYNC_FLUSH ends the block and aligns, as zlib does), finish once at the end, and take the output with read. Each block is coded on its own (block), so a flush costs the repeats across it. Level 0 stores the data.

Opaque: create and use it through this module's functions.

`DecodeError`

gizlang

type DecodeError = { code: i64; offset: i64; message: string; }

Why a decoder stopped: code is one of the constants below, offset is the input byte where the decoder found the problem, message tells what it is.

code: i64
offset: i64
message: string

`Inflater`

gizlang

type Inflater

A streaming DEFLATE decoder: give it input with write and close, and take the output with read; or call feed for each piece and finish at the end.

Opaque: create and use it through this module's functions.

`Xxh64`

gizlang

type Xxh64

XXH64 over data given in pieces, as zstd checks a frame: four lanes of 8 bytes, and the bytes of the last partial stripe waiting in pending.

Opaque: create and use it through this module's functions.

`ZstdDecoder`

gizlang

type ZstdDecoder

A streaming Zstandard decoder: give it input with write and close, and take the output with read; or call feed for each piece and finish at the end. It decodes each frame of the input, and skips skippable frames.

Opaque: create and use it through this module's functions.

`TarMember`

gizlang

type TarMember = { path: string; kind: string; mode: i64; data: bytes; link: string; }

One archive member. kind is "file", "directory", "symlink", "hardlink" or "other" (devices and FIFOs); link is the target of a link.

path: string
kind: string
mode: i64
data: bytes
link: string

`BrotliEncoder`

gizlang

type BrotliEncoder

A Brotli encoder: write(data) takes input, operate(op) runs PROCESS/FLUSH/FINISH, read() gives what came out.

Opaque: create and use it through this module's functions.

`BrotliDecoder`

gizlang

type BrotliDecoder

A Brotli decoder: write(data) decodes what it can; an error is libbrotli's message.

Opaque: create and use it through this module's functions.

`Alp`

gizlang

type Alp = { exponent: i64; digits: Vec<i64>; at: Vec<i64>; exceptions: Vec<f64>; }

A vector of doubles as ALP integers: digits[i] / 10^exponent, except at the positions at, whose values are exceptions.

exponent: i64
digits: Vec<i64>
at: Vec<i64>
exceptions: Vec<f64>

`ZipWriter`

gizlang

type ZipWriter

A zip archive, written in order: the caller writes what each call returns. An entry comes whole (file: its bytes stored or deflated, its CRC and sizes in its header) or as it streams (entry, then data for each piece of its bytes, which the caller writes as they are, then a data descriptor). A streamed entry is stored: most bytes people keep are compressed already, and storing keeps the archive at disk speed. Names are UTF-8 (flag bit 11 when a name is not ASCII). A modified time goes as a DOS time and as UTC seconds (extra 0x5455); modified 0 writes no time (1980-01-01 and no extra field), as the first entry of an OCF container needs. ZIP64 records come in only where a size, an offset or the count needs them. finish writes the central directory.

Opaque: create and use it through this module's functions.

`ZipEntry`

gizlang

type ZipEntry = { name: string; size: i64; stored: i64; method: u64; crc: u64; modified: i64; offset: i64; }

One entry of a zip archive, as its central directory records it: NAME (a folder's ends in "/"), SIZE bytes, STORED of them in the archive by METHOD (0 stored, 8 deflated), their CRC, MODIFIED (ms since 1970: extra 0x5455's UTC seconds, else the DOS time read as UTC, 0 for none) and OFFSET, where its local header is.

name: string
size: i64
stored: i64
method: u64
crc: u64
modified: i64
offset: i64

Functions

`crc32`

gizlang

function crc32(data: bytes): u64

The CRC-32 of data, as gzip and zip record it.

Effects: fail.

`newCrc32`

gizlang

function newCrc32(): Crc32

A CRC-32 checksum (the one of zlib, gzip and zip) of no data.

`crc32Combine`

gizlang

function crc32Combine(first: u64, second: u64, secondBytes: i64): u64 requires secondBytes> = 0 { let factor = CRC32_TOP_BIT

CRC-32 of concatenated regions from their digests and the second length, without joining or rereading their buffers.

Effects: fail.

`newCrc32c`

gizlang

function newCrc32c(): Crc32c

A CRC-32C (Castagnoli) checksum of no data.

`crc32c`

gizlang

function crc32c(data: bytes): u64

The CRC-32C checksum of DATA.

Effects: fail.

`crc16Xmodem`

gizlang

function crc16Xmodem(data: bytes): u64

CRC-16/XMODEM: polynomial 0x1021, initial zero, no reflection or final xor.

Effects: fail.

`lz4`

gizlang

function lz4(data: bytes): bytes

DATA as one LZ4 block (the LZ4 block format, no frame): greedy matches of 4 or more bytes within 64 KB, found in one table of 4-byte prefixes (hash4, common). It is fast, not small: for bytes that are written and read often. A run of misses makes the search step longer, so data that does not compress costs little.

Effects: fail.

`unlz4`

gizlang

function unlz4(block: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { let out = b""

The data of the LZ4 block BLOCK, at most LIMIT bytes of output.

Effects: fail.

`deflate`

gizlang

function deflate(data: bytes): bytes

data as one DEFLATE stream (no header): a single final block.

Effects: fail.

`gzip`

gizlang

function gzip(data: bytes): bytes

data as a gzip member: header, DEFLATE stream, CRC-32 and length.

Effects: fail.

`newDeflater`

gizlang

function newDeflater(framing: i64, level: i64): Deflater requires framing> = RAW && framing <= GZIP

A Deflate compressor at LEVEL (0 to 9) with FRAMING: RAW, ZLIB or GZIP.

Effects: fail.

`adler32`

gizlang

function adler32(data: bytes): u64

The Adler-32 checksum of data (RFC 1950), as zlib records it.

Effects: fail.

`newInflater`

gizlang

function newInflater(framing: i64, limit: i64): Inflater requires framing> = RAW && framing <= GZIP requires limit> = 0 { let state = I_HEADER

A decoder for one framing (RAW, ZLIB or GZIP) that refuses more than limit bytes of output. GZIP decodes each member of a multi-member file.

Effects: fail.

`inflater`

gizlang

function inflater(framing: i64): Inflater requires framing> = RAW && framing <= GZIP

A decoder of framing RAW, ZLIB or GZIP with no output limit, for feed and finish.

Effects: fail.

`inflate`

gizlang

function inflate(data: bytes, framing: i64, limit: i64): bytes throws DecodeError requires framing> = RAW && framing <= GZIP requires limit> = 0 { let d = new Inflater(framing, limit)

The DEFLATE stream data decoded (framing RAW, ZLIB or GZIP), at most limit bytes of output.

Effects: fail.

`gunzip`

gizlang

function gunzip(data: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { return inflate(data, GZIP, limit)

The gzip file data decoded (every member), at most limit bytes of output.

Effects: fail.

`newXxh64`

gizlang

function newXxh64(seed: u64): Xxh64

A new XXH64 hash state with SEED.

`xxh64`

gizlang

function xxh64(data: bytes, seed: u64): u64

The XXH64 of data with a seed.

Effects: fail.

`newZstdDecoder`

gizlang

function newZstdDecoder(limit: i64, windowLimit: i64): ZstdDecoder requires limit> = 0 && windowLimit> = 0 { return { _limit: limit, _windowLimit: windowLimit, _input: b"", _at: 0, _base: 0, _ended: false, _end: 0, _state: Z_MAGIC, _skip: 0, _frames: 0, _window: 0, _fcs: -1, _frameOut: 0, _hasChecksum: false, _blockMax: 0, _buf: b"", _pos: 0, _start: 0, _floor: 0, _produced: 0, _hash: new Xxh64(0u), _lits: filled(ZSTD_BLOCK + 64, 0u), _tables: noEntropy(), _dictTables: noEntropy(), _dict: b"", _dictId: 0, _llDefault: fseTable(literalLengthDefault(), 6, FSE_LITERALS), _mlDefault: fseTable(matchLengthDefault(), 6, FSE_MATCHES), _ofDefault: fseTable(offsetDefault(), 5, FSE_OFFSETS), _error: 0, _errorAt: 0, _message: "", }

A decoder that refuses more than limit bytes of output and frames with a window over windowLimit bytes (ZSTD_WINDOW_LIMIT is the zstd tool's). Its memory is about twice the window of the frame, and no more than the limit.

Effects: fail.

`zstdDecoder`

gizlang

function zstdDecoder(): ZstdDecoder

A decoder with no output limit and windows up to ZSTD_WINDOW_LIMIT, for feed and finish.

Effects: fail.

`unzstd`

gizlang

function unzstd(data: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { let d = new ZstdDecoder(limit, ZSTD_WINDOW_LIMIT)

The Zstandard data decoded (every frame), at most limit bytes of output, with windows up to ZSTD_WINDOW_LIMIT.

Effects: fail.

`unzstdWith`

gizlang

function unzstdWith(data: bytes, dictionary: bytes, limit: i64): bytes throws DecodeError requires limit> = 0 { let d = new ZstdDecoder(limit, ZSTD_WINDOW_LIMIT)

unzstd with a dictionary (see useDictionary).

Effects: fail.

`untar`

gizlang

function untar(archive: bytes, limit: i64): Vec<TarMember> throws DecodeError requires limit> = 0 { let members: Vec<TarMember> = []

Every member of archive in order, with pax and GNU long-name headers applied to the member after them. It reads the archive as given: the caller decides which members to keep. It fails (CORRUPT) on a header whose checksum is wrong or whose data runs past the archive, and (TOO_LARGE) when the members hold more than limit bytes (their bodies and the pax and long-name records).

Effects: fail.

`tarPadding`

gizlang

function tarPadding(size: i64): i64

The zero bytes after a member body of size bytes, to the next 512-byte block.

Effects: fail.

`tarHeader`

gizlang

function tarHeader(path: string, mode: i64, size: i64, link: string): bytes

The header blocks of one member fixed by its fields alone (owner 0, time 0): a pax header when PATH or LINK is longer than 100 bytes, then the ustar block. A member with a LINK is a hard link with no body; otherwise it is a file of SIZE bytes, whose body and tarPadding(size) zero bytes follow. Two archives of the same members are the same bytes.

Effects: fail.

`newBrotliEncoder`

gizlang

function newBrotliEncoder(): BrotliEncoder

A Brotli compressor with the default parameters.

`brotli`

gizlang

function brotli(data: bytes, quality: i64): Result<bytes, string>

DATA in one Brotli stream at QUALITY with a 4 MB window (22).

Effects: fail.

`newBrotliDecoder`

gizlang

function newBrotliDecoder(): BrotliDecoder

A Brotli decompressor with the default parameters.

`fsstEncode`

gizlang

function fsstEncode(data: bytes): bytes

data compressed by FSST: its length (u64), the symbol table (a count, then each symbol's length and bytes) and the codes. Sizes and contents of the input are kept exactly; fsstDecode reads it back.

Effects: fail.

`fsstDecode`

gizlang

function fsstDecode(data: bytes): bytes throws string

The bytes of an FSST-compressed block (its symbol table, then the codes).

Effects: fail.

`fsstDecodeRanges`

gizlang

function fsstDecodeRanges(data: bytes, from: Vec<i64>, to: Vec<i64>): bytes throws string

The bytes [FROM[k], TO[k]) of fsstDecode(DATA) for each k, joined: FROM ascending, the ranges apart. The codes before a range are only counted, and decoding stops after the last range: a top-k's few rows of a block of 100K strings (ClickBench Q23).

Effects: fail.

`alpEncode`

gizlang

function alpEncode(v: Vec<f64>): Alp

The values of V in ALP form: integers at a decimal scale, with the values that do not fit kept apart.

Effects: fail.

`alpDecode`

gizlang

function alpDecode(a: Alp): Vec<f64> throws string

The doubles of a, or an error for an exponent or exception position out of range.

Effects: fail.

`newZipWriter`

gizlang

function newZipWriter(): ZipWriter

A writer of a zip archive in memory, with no entries.

`zipEntries`

gizlang

function zipEntries(size: i64, read: (at: i64, count: i64) => Result<bytes, string>, most: i64): Vec<ZipEntry> throws DecodeError

The first MOST entries of the zip archive of SIZE bytes that READ(at, count) reads, in their central directory's order, ZIP64 included. It reads the end records and the central directory, never an entry's bytes. A name that is not UTF-8 (an old archive's code page) shows each byte past ASCII as U+FFFD.

Effects: fail, read, write, console, io.

`unzipEntry`

gizlang

function unzipEntry(e: ZipEntry, read: (at: i64, count: i64) => Result<bytes, string>, limit: i64): bytes throws DecodeError requires limit> = 0 { if (e.size> limit) { return Result.err(DecodeError(TOO_LARGE, e.offset, `zip: ${ e.name } has ${ e.size } bytes, over the limit of ${ limit }`))

The bytes of entry E of the archive that READ(at, count) reads, checked against its CRC: TOO_LARGE past LIMIT bytes, UNSUPPORTED when it is encrypted or packed by a method other than stored or deflated.

Effects: fail, read, write, console, io.

Methods

`Crc32.update`

gizlang

function Crc32.update(self: mut Crc32, data: bytes): void

Adds DATA to the checksum.

Effects: fail.

`Crc32.digest`

gizlang

function Crc32.digest(self: Crc32): u64

The checksum of the data added so far.

Effects: fail.

`Crc32c.update`

gizlang

function Crc32c.update(self: mut Crc32c, data: bytes): void

Chunk boundaries never alter the checksum; data can remain in its current buffers.

Effects: fail.

`Crc32c.digest`

gizlang

function Crc32c.digest(self: Crc32c): u64

The checksum of the data added so far.

Effects: fail.

`Deflater.level`

gizlang

function Deflater.level(self: Deflater): i64

The compression level (0 to 9).

`Deflater.setLevel`

gizlang

function Deflater.setLevel(self: mut Deflater, level: i64): void

Sets the compression level (0 to 9) for the input that follows.

`Deflater.finished`

gizlang

function Deflater.finished(self: Deflater): bool

Whether the stream has ended (a FINISH flush is done).

`Deflater.read`

gizlang

function Deflater.read(self: mut Deflater): bytes

The output produced so far, taken.

`Deflater.write`

gizlang

function Deflater.write(self: mut Deflater, input: bytes): void requires!self._finished

Add input; whole blocks of it are coded as they fill.

Effects: fail.

`Deflater.flush`

gizlang

function Deflater.flush(self: mut Deflater, kind: i64): void

The pending input coded (KIND other than NO_FLUSH); SYNC_FLUSH and FULL_FLUSH add an empty stored block so the output ends on a byte with all the input decodable; FINISH ends the stream with its trailer.

Effects: fail.

`Inflater.write`

gizlang

function Inflater.write(self: mut Inflater, input: bytes): void requires!self._ended

Add input. The decoder keeps only the input that it has not decoded.

Effects: fail.

`Inflater.close`

gizlang

function Inflater.close(self: mut Inflater): void

Mark the end of the input. After it, a stream that has not ended is TRUNCATED.

Effects: fail.

`Inflater.done`

gizlang

function Inflater.done(self: Inflater): bool

Whether the stream has ended and all its output was read.

`Inflater.read`

gizlang

function Inflater.read(self: mut Inflater): bytes throws DecodeError

The next output, at most 256 KiB. Empty when the decoder needs input (write more, or close) or when it is done. An error stays: each later read returns it again.

Effects: fail.

`Inflater.feed`

gizlang

function Inflater.feed(self: mut Inflater, input: bytes): bytes throws string

Write input and return all the output that it makes now.

Effects: fail.

`Inflater.finish`

gizlang

function Inflater.finish(self: mut Inflater): bytes throws string

End the input and return the rest of the output. A stream that has not ended is an error.

Effects: fail.

`Xxh64.update`

gizlang

function Xxh64.update(self: mut Xxh64, data: bytes, from: i64, to: i64): void requires from> = 0 && from <= to && to <= data.length { self._total + = to - from

Add the bytes from..to of data.

Effects: fail.

`Xxh64.digest`

gizlang

function Xxh64.digest(self: Xxh64): u64

The XXH64 of the bytes so far.

Effects: fail.

`ZstdDecoder.useDictionary`

gizlang

function ZstdDecoder.useDictionary(self: mut ZstdDecoder, dictionary: bytes): i64 throws DecodeError

Use a dictionary for the frames that follow: a zstd dictionary (its entropy tables, repeat offsets and content) or, without the dictionary magic, raw content. Its ID is what a frame names (0 for raw content).

Effects: fail.

`ZstdDecoder.write`

gizlang

function ZstdDecoder.write(self: mut ZstdDecoder, input: bytes): void requires!self._ended

Add input. The decoder keeps only the input that it has not decoded.

Effects: fail.

`ZstdDecoder.close`

gizlang

function ZstdDecoder.close(self: mut ZstdDecoder): void

Mark the end of the input. After it, a frame that has not ended is TRUNCATED.

Effects: fail.

`ZstdDecoder.done`

gizlang

function ZstdDecoder.done(self: ZstdDecoder): bool

Whether the input has ended after a whole frame, and all output was read.

`ZstdDecoder.read`

gizlang

function ZstdDecoder.read(self: mut ZstdDecoder): bytes throws DecodeError

The next output, at most 1 MiB. Empty when the decoder needs input (write more, or close) or when it is done. An error stays: each later read returns it again.

Effects: fail.

`ZstdDecoder.feed`

gizlang

function ZstdDecoder.feed(self: mut ZstdDecoder, input: bytes): bytes throws string

Write input and return all the output that it makes now.

Effects: fail.

`ZstdDecoder.finish`

gizlang

function ZstdDecoder.finish(self: mut ZstdDecoder): bytes throws string

End the input and return the rest of the output. A frame that has not ended is an error.

Effects: fail.

`BrotliEncoder.setParameter`

gizlang

function BrotliEncoder.setParameter(self: mut BrotliEncoder, param: i64, value: i64): bool

Sets the parameter PARAM (BROTLI_QUALITY or BROTLI_WINDOW) to VALUE; false when libbrotli refuses it.

`BrotliEncoder.finished`

gizlang

function BrotliEncoder.finished(self: BrotliEncoder): bool

Whether the stream has ended.

`BrotliEncoder.write`

gizlang

function BrotliEncoder.write(self: mut BrotliEncoder, input: bytes, op: i64): bool

INPUT compressed with OP; the output joins the pending bytes. False when libbrotli refused.

Effects: fail.

`BrotliEncoder.read`

gizlang

function BrotliEncoder.read(self: mut BrotliEncoder): bytes

The output produced so far, taken.

`BrotliEncoder.close`

gizlang

function BrotliEncoder.close(self: mut BrotliEncoder): void

Frees the compressor. It does nothing after the first call.

`BrotliDecoder.errorCode`

gizlang

function BrotliDecoder.errorCode(self: BrotliDecoder): i64

libbrotli's BrotliDecoderErrorCode of the last failed write (negative), 0 when none.

`BrotliDecoder.setParameter`

gizlang

function BrotliDecoder.setParameter(self: mut BrotliDecoder, param: i64, value: i64): bool

Sets the decoder parameter PARAM to VALUE; false when libbrotli refuses it.

`BrotliDecoder.done`

gizlang

function BrotliDecoder.done(self: BrotliDecoder): bool

Whether the stream has ended.

`BrotliDecoder.write`

gizlang

function BrotliDecoder.write(self: mut BrotliDecoder, input: bytes): bool throws string

Decompresses INPUT; the output joins the pending bytes. It fails on bad data or after close.

Effects: fail.

`BrotliDecoder.read`

gizlang

function BrotliDecoder.read(self: mut BrotliDecoder): bytes

The output produced so far, taken.

`BrotliDecoder.close`

gizlang

function BrotliDecoder.close(self: mut BrotliDecoder): void

Frees the decompressor. It does nothing after the first call.

`ZipWriter.entry`

gizlang

function ZipWriter.entry(self: mut ZipWriter, name: string, modified: i64): bytes

The local header of a streamed entry NAME (a folder ends in "/"), modified at MODIFIED (ms since 1970, 0: no time); it ends the streamed entry before.

Effects: fail.

`ZipWriter.data`

gizlang

function ZipWriter.data(self: mut ZipWriter, data: bytes): void requires self._open && !self._folder

Counts DATA, the next bytes of the streamed entry, which the caller writes as they are.

Effects: fail.

`ZipWriter.file`

gizlang

function ZipWriter.file(self: mut ZipWriter, name: string, modified: i64, data: bytes, deflated: bool): bytes requires data.length <4294967295 { let out = self.closeEntry()

Entry NAME whole: its header and DATA, deflated when DEFLATED and that is smaller, modified at MODIFIED (ms since 1970, 0: no time). It ends the streamed entry before.

Effects: fail.

`ZipWriter.finish`

gizlang

function ZipWriter.finish(self: mut ZipWriter): bytes

The end of the archive: a streamed entry's descriptor, the central directory and the end records.

Effects: fail.

Constants

`NO_FLUSH`

gizlang

const NO_FLUSH = 0

The flush mode no flush, 0.

`PARTIAL_FLUSH`

gizlang

const PARTIAL_FLUSH = 1

The flush mode partial flush, 1.

`SYNC_FLUSH`

gizlang

const SYNC_FLUSH = 2

The flush mode sync flush, 2.

`FULL_FLUSH`

gizlang

const FULL_FLUSH = 3

The flush mode full flush, 3.

`FINISH`

gizlang

const FINISH = 4

The flush mode finish, 4.

`BLOCK_FLUSH`

gizlang

const BLOCK_FLUSH = 5

The flush mode block flush, 5.

`CORRUPT`

gizlang

const CORRUPT = 1

The input is not a valid stream.

`TRUNCATED`

gizlang

const TRUNCATED = 2

The input ends before the stream does.

`TOO_LARGE`

gizlang

const TOO_LARGE = 3

The output, or the window that a frame asks for, is over the limit of the caller.

`CHECKSUM`

gizlang

const CHECKSUM = 4

A checksum or a recorded length does not agree with the output.

`UNSUPPORTED`

gizlang

const UNSUPPORTED = 5

The stream uses a feature that the decoder does not have (a zlib preset dictionary).

`NEEDS_DICTIONARY`

gizlang

const NEEDS_DICTIONARY = 6

The frame needs a dictionary that the decoder does not have.

`RAW`

gizlang

const RAW = 0

DEFLATE framings: no framing (RFC 1951), zlib (RFC 1950) and gzip (RFC 1952).

`ZLIB`

gizlang

const ZLIB = 1

The zlib framing (RFC 1950).

`GZIP`

gizlang

const GZIP = 2

The gzip framing (RFC 1952).

`ZSTD_WINDOW_LIMIT`

gizlang

const ZSTD_WINDOW_LIMIT = 134217728

The default window limit, as the zstd tool's (2^27).

`BROTLI_PROCESS`

gizlang

const BROTLI_PROCESS = 0

BrotliEncoderOperation.

`BROTLI_FLUSH`

gizlang

const BROTLI_FLUSH = 1

The flush mode brotli flush, 1.

`BROTLI_FINISH`

gizlang

const BROTLI_FINISH = 2

The flush mode brotli finish, 2.

`BROTLI_QUALITY`

gizlang

const BROTLI_QUALITY = 1

BrotliEncoderParameter: the quality (0 to 11) and the window (log2 of its size, 10 to 24).

`BROTLI_WINDOW`

gizlang

const BROTLI_WINDOW = 2

The parameter of the window size, as log2 of its bytes (10 to 24).