Pure MoonBit zlib/deflate implementation.

zlib

deflate

moon add mizchi/zlib@0.4.9

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Author

mizchi

Version

0.4.9

License

Apache-2.0

Repository

github.com/mizchi/zlib.mbt

Last updated

20 hours ago

Downloads

184K

Dependencies

moonbitlang/x0.4.40
moonbitlang/async0.16.6

README

#mizchi/zlib

Pure MoonBit zlib/deflate implementation. Supports:

zlib streams (compress stored / full inflate)
raw deflate (stored compress / full inflate)
gzip (stored compress / full inflate)

///|
test "roundtrip stored" {
  let data : Bytes = "hello"
  let compressed = zlib_compress_stored(data)
  let decompressed = zlib_decompress_stored(compressed)
  inspect(decompressed.length(), content="5")
  inspect(decompressed[0], content="b'\\x68'")
  inspect(decompressed[4], content="b'\\x6F'")
}

#Native target

mizchi/zlib itself is pure MoonBit on every target, including native.

If you want the system zlib backend explicitly, import mizchi/zlib/native:

import "mizchi/zlib/native" as @zlib_native

let compressed = @zlib_native.zlib_compress(data)
let decompressed = @zlib_native.zlib_decompress(compressed)

mizchi/zlib/native links -lz internally, so dependents do not need to add native linker flags themselves.

# Benchmarks
moon bench --target js
moon bench --target native
just bench-compare

#Benchmark (Rust flate2 / miniz_oxide baseline)

Measured on 2026-01-28 with hyperfine --warmup 3 and the bundled 256KiB fixtures. Commands are very short (<5ms), so shell overhead can skew results. wasm/wasm-gc uses moon run, so the runtime/launcher overhead is included.

Format	MoonBit native (mean)	Rust baseline (mean)	Relative	MoonBit wasm (mean)	MoonBit wasm-gc (mean)
zlib	3.8 ms	2.1 ms (flate2/miniz_oxide)	1.8x slower	31.8 ms	22.9 ms
deflate	3.7 ms	2.1 ms (flate2/miniz_oxide)	1.8x slower	30.0 ms	22.6 ms
gzip	4.2 ms	2.2 ms (flate2/miniz_oxide)	1.9x slower	30.7 ms	27.1 ms

#
ZlibError

source

pub(all) suberror ZlibError {
  InvalidData(String)
  OutputTooLarge(String)
} derive(Eq)

Errors raised by zlib helpers.

InvalidData covers malformed inputs (bad headers, checksum mismatches, truncated streams, invalid Huffman codes, etc.).

OutputTooLarge is raised when decompressed output would exceed the configured max_size. Decompression APIs accept a max_size~ labeled argument; the default is default_max_decompressed_size (256 MiB).

impl Show for ZlibError

#
adler32

source

fn adler32(data : Bytes) -> Int

Compute Adler-32 checksum.

#
adler32_fixed

source

fn adler32_fixed(data : FixedArray[Byte]) -> Int

Compute Adler-32 checksum from FixedArray.

#
crc32

source

fn crc32(data : Bytes) -> UInt

Reflected CRC-32 (zlib/gzip polynomial 0xEDB88320). Slicing-by-8 bulk path delegates to a target-conditional inner loop (crc32_bulk_impl), then finishes the trailing 0–7 bytes with the standard byte table.

Inner loop dispatch:

wasm — crc32_simd.mbt, inline-WAT with direct i32.loads of the input bytes and 8 parallel i32.loads from a flattened slicing-by-8 table.
other — crc32_scalar.mbt, pure-MoonBit slicing-by-8.

#
crc32_fixed

source

fn crc32_fixed(data : FixedArray[Byte]) -> UInt

#
default_max_decompressed_size

source

let default_max_decompressed_size : Int

Default maximum decompressed output size (256 MiB).

All public decompression functions enforce this by default to prevent "zip bomb" style DoS where a tiny crafted input decompresses to gigabytes of memory. Override via the max_size~ labeled argument.

#
deflate_compress

source

fn deflate_compress(data : Bytes) -> Bytes

Compress raw deflate stream (best compression).

#
deflate_compress_best

source

fn deflate_compress_best(data : Bytes) -> Bytes

#
deflate_compress_fixed

source

fn deflate_compress_fixed(data : Bytes) -> Bytes

#
deflate_compress_stored

source

fn deflate_compress_stored(data : Bytes) -> Bytes

Compress raw deflate stream using stored blocks (no compression).

#
deflate_decompress

source

fn deflate_decompress(data : Bytes, max_size? : Int) -> Bytes raise ZlibError

Decompress a full raw deflate stream.

#
deflate_decompress_at

source

fn deflate_decompress_at(data : Bytes, start : Int, max_size? : Int) -> (Bytes, Int) raise ZlibError

Decompress raw deflate stream from the given offset.

#
gzip_compress

source

fn gzip_compress(data : Bytes) -> Bytes

Compress data using gzip (stored blocks).

#
gzip_compress_stored

source

fn gzip_compress_stored(data : Bytes) -> Bytes

Compress gzip stream using stored deflate blocks (no compression).

#
gzip_decompress

source

fn gzip_decompress(data : Bytes, max_size? : Int) -> Bytes raise ZlibError

Decompress a full gzip stream.

#
gzip_decompress_at

source

fn gzip_decompress_at(data : Bytes, start : Int, max_size? : Int) -> (Bytes, Int) raise ZlibError

Decompress gzip stream from the given offset.

#
zlib_compress

source

fn zlib_compress(data : Bytes) -> Bytes

Compress data using zlib (fixed Huffman).

#
zlib_compress_stored

source

fn zlib_compress_stored(data : Bytes) -> Bytes

Compress data using zlib stored blocks (no actual compression) Format: CMF(0x78) + FLG(0x01) + blocks + Adler32

#
zlib_decompress

source

fn zlib_decompress(data : Bytes, max_size? : Int) -> Bytes raise ZlibError

Decompress a full zlib stream.

#
zlib_decompress_at

source

fn zlib_decompress_at(data : Bytes, start : Int, max_size? : Int) -> (Bytes, Int) raise ZlibError

Decompress a zlib stream (deflate with checksum) from the given offset. Returns (decompressed_bytes, next_offset).

Output is capped at max_size bytes; if exceeded, raises OutputTooLarge.

#
zlib_decompress_stored

source

fn zlib_decompress_stored(data : Bytes, max_size? : Int) -> Bytes raise ZlibError

Decompress zlib stored blocks (single stream)

#
zlib_decompress_stored_at

source

fn zlib_decompress_stored_at(data : Bytes, start : Int, max_size? : Int) -> (Bytes, Int) raise ZlibError

Decompress zlib stored blocks from the given offset. Returns (decompressed_bytes, next_offset).

Output is capped at max_size bytes; if exceeded, raises OutputTooLarge rather than allowing unbounded allocation.

Source Files

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zlib

#mizchi/zlib

#Native target

#Benchmark (Rust flate2 / miniz_oxide baseline)

#ZlibError

#adler32

#adler32_fixed

#crc32

#crc32_fixed

#default_max_decompressed_size

#deflate_compress

#deflate_compress_best

#deflate_compress_fixed

#deflate_compress_stored

#deflate_decompress

#deflate_decompress_at

#gzip_compress

#gzip_compress_stored

#gzip_decompress

#gzip_decompress_at

#zlib_compress

#zlib_compress_stored

#zlib_decompress

#zlib_decompress_at

#zlib_decompress_stored

#zlib_decompress_stored_at

Source Files

#
ZlibError

#
adler32

#
adler32_fixed

#
crc32

#
crc32_fixed

#
default_max_decompressed_size

#
deflate_compress

#
deflate_compress_best

#
deflate_compress_fixed

#
deflate_compress_stored

#
deflate_decompress

#
deflate_decompress_at

#
gzip_compress

#
gzip_compress_stored

#
gzip_decompress

#
gzip_decompress_at

#
zlib_compress

#
zlib_compress_stored

#
zlib_decompress

#
zlib_decompress_at

#
zlib_decompress_stored

#
zlib_decompress_stored_at