Crate jkl 

JKL - blazingly fast compression and image processing toolkit

JKL is a batteries-included Rust crate for compressing, encoding and packing data that needs to travel fast and decompress even faster - on the CPU or directly on the GPU. If you ship textures, sprite atlases, tile maps, or any bulk binary payload that must be ready the instant it hits VRAM, JKL was built for you.

Feature highlights

• GPU-oriented block texture codecs - encode and decode BC1 through BC5 blocks with cluster-fit quality (bc1, bc2, bc3, bc4, bc5, powered by cluster_fit).
• Layered entropy coding - stack lz77 or rle with ans for near-optimal compression ratios while keeping decompression blazingly fast
  • simple enough for a GPU compute shader.
• Bit-perfect I/O - the bits module reads and writes individual bits so every encoder can squeeze out every last fraction of a byte.
• Jackal Image format - the jackal::image module ties everything together into a tiled, mip-mapped, GPU-ready image container.
• Packing and spatial indexing - max_rects bin-packs rectangles for atlas generation; z_curve provides Morton-order iteration for cache-friendly traversal.

Quick orientation - “how do I …?”

I want to …	Start here
Compress a texture to BC1–BC5	bc1::Block::encode, bc2::Block::encode, bc3::Block::encode, bc4::Block::encode, bc5::Block::encode
Decompress a BC block	bc1::Block::decode, bc2::Block::decode, bc3::Block::decode, bc4::Block::decode, bc5::Block::decode
Write / read a complete Jackal Image file	jackal::image::write_image, jackal::image::JackalReader
Entropy-code a symbol stream	Build an ans::Context, then use ans::Encoder / ans::Decoder
Run-length encode an iterator	rle::rle, rle::rle_power_of_two, or rle::rle_with_cfg
LZ77-compress a value stream	lz77::Encoder → lz77::Token stream → lz77::Decoder
LZ78-compress a value stream	lz78::Encoder → lz78::Token stream → lz78::Decoder
Encode small unsigned ints compactly	vle::encode / vle::decode (Elias delta), or wrap with vle::Vle
Map signed ints for better compression	zigzaq::ZigZag::zigzag before VLE encoding
Read / write individual bits	bits::WriteBits, bits::ReadBits, or the bits::write_bits_scope helper
Bin-pack rectangles into an atlas	max_rects::MaximalRectangles::new then insert in a loop
Work with 2D pixel buffers	image::Image2DRef / image::Image2DMut
Use vector math or pixel types	math::Vec3, math::Rgb565, math::Rgba32F, etc.

Module overview

Compression

Module	Purpose
ans	Asymmetric Numeral Systems (ANS) entropy coder
rle	Run-length encoding with configurable max length and power-of-two mode
vle	Variable-length Elias delta coding for unsigned integers
lz77	LZ77 sliding-window compressor / decompressor
lz78	LZ78 dictionary compressor (GPU-friendly variant)
zigzaq	Zigzag signed ↔ unsigned mapping for better VLE compression

Block-texture codecs

Module	Format	Block size	Channels
[bc1]	BC1 / DXT1	8 bytes	RGB + 1-bit A
[bc2]	BC2 / DXT3	16 bytes	RGBA (4-bit A)
[bc3]	BC3 / DXT5	16 bytes	RGBA (interp A)
[bc4]	BC4 / RGTC1	8 bytes	R
[bc5]	BC5 / RGTC2	16 bytes	RG
cluster_fit	Shared quantizer for above	-	-

Image and math

Module	Purpose
image	Non-owning 2D / 3D image views (Image2DRef, Image2DMut, …)
math	Vectors (Vec2–Vec4), pixel types, Rect, PCA, bit-interleaving

I/O and serialization

Module	Purpose
bits	Bit-level buffered reader / writer over byte streams
encode	FixedCode and VarCode serialization traits

Packing and spatial

Module	Purpose
max_rects	2D bin packing (maximal-rectangles algorithm) for atlas generation
z_curve	Z-order / Morton curve coordinate iteration

File formats

Module	Purpose
jackal::image	Tiled, GPU-decompressible image container format

Modules

ans

Asymmetric Numeral Systems (ANS) entropy coder.

bits

Types and functions to work with individual bits.

cluster_fit

Least-squares cluster-fit quantization.

encode

Traits for fixed-size and variable-length binary serialization.

image

jackal

Jackal file format.

lz77

LZ77 sliding-window compression.

lz78

LZ78 dictionary compression.

math

Linear algebra primitives, color types, and bit-manipulation utilities.

max_rects

2D rectangle bin packing via the maximal-rectangles algorithm.

palette

rle

Run-length encoding (RLE) compression.

vle

Variable-length Elias delta encoding for unsigned integers.

z_curve

Z-order (Morton) curve utilities for 2D coordinate interleaving.

zigzaq

Zigzag encoding that maps signed integers to unsigned integers.