ZXC: High-Performance Asymmetric Lossless Compression

ZXC is a high-performance, lossless, asymmetric compression library optimized for Content Delivery and Embedded Systems (Game Assets, Firmware, App Bundles). It is designed to be "Write Once, Read Many". Unlike codecs like LZ4, ZXC trades compression speed (build-time) for maximum decompression throughput (run-time).

TL;DR

• What: A C library for lossless compression, optimized for maximum decompression speed.
• Key Result: Up to >40% faster decompression than LZ4 on Apple Silicon, >25% faster on Google Axion (ARM64), >5% faster on x86_64, all with better compression ratios.
• Use Cases: Game assets, firmware, app bundles, anything compressed once, decompressed millions of times.
• Install: vcpkg install zxc · pip install zxc-compress · cargo add zxc-compress
• Quality: Fuzzed, sanitized, formally tested, thread-safe API. BSD-3-Clause.

Verified: ZXC has been officially merged into the lzbench master branch. You can now verify these results independently using the industry-standard benchmark suite.

ZXC Design Philosophy

Traditional codecs often force a trade-off between symmetric speed (LZ4) and archival density (Zstd).

ZXC focuses on Asymmetric Efficiency.

Designed for the "Write-Once, Read-Many" reality of software distribution, ZXC utilizes a computationally intensive encoder to generate a bitstream specifically structured to maximize decompression throughput. By performing heavy analysis upfront, the encoder produces a layout optimized for the instruction pipelining and branch prediction capabilities of modern CPUs, particularly ARMv8, effectively offloading complexity from the decoder to the encoder.

• Build Time: You generally compress only once (on CI/CD).
• Run Time: You decompress millions of times (on every user's device). ZXC respects this asymmetry.

👉 Read the Technical Whitepaper

Benchmarks

To ensure consistent performance, benchmarks are automatically executed on every commit via GitHub Actions. We monitor metrics on both x86_64 (Linux) and ARM64 (Apple Silicon M2) runners to track compression speed, decompression speed, and ratios.

(See the latest benchmark logs)

1. Mobile & Client: Apple Silicon (M2)

Scenario: Game Assets loading, App startup.

Target	ZXC vs Competitor	Decompression Speed	Ratio	Verdict
1. Max Speed	ZXC -1 vs LZ4 --fast	11,934 MB/s vs 5,647 MB/s 2.11x Faster	61.5 vs 62.2 Smaller (-1.0%)	ZXC leads in raw throughput.
2. Standard	ZXC -3 vs LZ4 Default	6,925 MB/s vs 4,804 MB/s 1.44x Faster	46.4 vs 47.6 Smaller (-2.6%)	ZXC outperforms LZ4 in read speed and ratio.
3. High Density	ZXC -5 vs Zstd --fast 1	6,090 MB/s vs 2,167 MB/s 2.81x Faster	40.6 vs 41.0 Equivalent (-1.0%)	ZXC outperforms Zstd in decoding speed.

2. Cloud Server: Google Axion (ARM Neoverse V2)

Scenario: High-throughput Microservices, ARM Cloud Instances.

Target	ZXC vs Competitor	Decompression Speed	Ratio	Verdict
1. Max Speed	ZXC -1 vs LZ4 --fast	8,727 MB/s vs 4,868 MB/s 1.79x Faster	61.5 vs 62.2 Smaller (-1.0%)	ZXC leads in raw throughput.
2. Standard	ZXC -3 vs LZ4 Default	5,130 MB/s vs 4,182 MB/s 1.23x Faster	46.4 vs 47.6 Smaller (-2.6%)	ZXC outperforms LZ4 in read speed and ratio.
3. High Density	ZXC -5 vs Zstd --fast 1	4,475 MB/s vs 1,763 MB/s 2.54x Faster	40.6 vs 41.0 Equivalent (-1.0%)	ZXC outperforms Zstd in decoding speed.

3. Build Server: x86_64 (AMD EPYC 7763)

Scenario: CI/CD Pipelines compatibility.

Target	ZXC vs Competitor	Decompression Speed	Ratio	Verdict
1. Max Speed	ZXC -1 vs LZ4 --fast	6,779 MB/s vs 4,116 MB/s 1.65x Faster	61.5 vs 62.2 Smaller (-1.0%)	ZXC achieves higher throughput.
2. Standard	ZXC -3 vs LZ4 Default	3,849 MB/s vs 3,573 MB/s 1.08x Faster	46.4 vs 47.6 Smaller (-2.6%)	ZXC offers improved speed and ratio.
3. High Density	ZXC -5 vs Zstd --fast 1	3,495 MB/s vs 1,573 MB/s 2.22x Faster	40.6 vs 41.0 Equivalent (-1.0%)	ZXC provides faster decoding.

(Benchmark Graph ARM64 : Decompression Throughput & Storage Ratio (Normalized to LZ4))

Benchmark ARM64 (Apple Silicon)

Benchmarks were conducted using lzbench 2.2.1 (from @inikep), compiled with Clang 17.0.0 using MOREFLAGS="-march=native" on macOS Sequoia 15.7.2 (Build 24G325). The reference hardware is an Apple M2 processor (ARM64). All performance metrics reflect single-threaded execution on the standard Silesia Corpus.

Compressor name	Compression	Decompress.	Compr. size	Ratio	Filename
memcpy	52905 MB/s	52854 MB/s	211938580	100.00	12 files
zxc 0.8.0 -1	950 MB/s	11934 MB/s	130408237	61.53	12 files
zxc 0.8.0 -2	615 MB/s	9879 MB/s	114657730	54.10	12 files
zxc 0.8.0 -3	240 MB/s	6925 MB/s	98234598	46.35	12 files
zxc 0.8.0 -4	169 MB/s	6584 MB/s	91698141	43.27	12 files
zxc 0.8.0 -5	93.2 MB/s	6090 MB/s	86054926	40.60	12 files
lz4 1.10.0	815 MB/s	4804 MB/s	100880147	47.60	12 files
lz4 1.10.0 --fast -17	1345 MB/s	5647 MB/s	131723524	62.15	12 files
lz4hc 1.10.0 -12	14.0 MB/s	4537 MB/s	77262399	36.46	12 files
zstd 1.5.7 -1	644 MB/s	1622 MB/s	73229468	34.55	12 files
zstd 1.5.7 --fast --1	725 MB/s	2167 MB/s	86932028	41.02	12 files
brotli 1.2.0 -0	539 MB/s	405 MB/s	78306095	36.95	12 files
snappy 1.2.2	830 MB/s	3265 MB/s	101352257	47.82	12 files

Benchmark ARM64 (Google Axion)

Benchmarks were conducted using lzbench 2.2.1 (from @inikep), compiled with GCC 12.2.0 using MOREFLAGS="-march=native" on Linux 64-bits Debian GNU/Linux 12 (bookworm). The reference hardware is a Google Neoverse-V2 processor (ARM64). All performance metrics reflect single-threaded execution on the standard Silesia Corpus.

Compressor name	Compression	Decompress.	Compr. size	Ratio	Filename
memcpy	24237 MB/s	24131 MB/s	211938580	100.00	12 files
zxc 0.8.0 -1	853 MB/s	8727 MB/s	130408237	61.53	12 files
zxc 0.8.0 -2	556 MB/s	7303 MB/s	114657730	54.10	12 files
zxc 0.8.0 -3	226 MB/s	5130 MB/s	98234598	46.35	12 files
zxc 0.8.0 -4	159 MB/s	4879 MB/s	91698141	43.27	12 files
zxc 0.8.0 -5	84.9 MB/s	4475 MB/s	86054926	40.60	12 files
lz4 1.10.0	749 MB/s	4182 MB/s	100880147	47.60	12 files
lz4 1.10.0 --fast -17	1303 MB/s	4868 MB/s	131723524	62.15	12 files
lz4hc 1.10.0 -12	12.9 MB/s	3796 MB/s	77262399	36.46	12 files
zstd 1.5.7 -1	527 MB/s	1364 MB/s	73229468	34.55	12 files
zstd 1.5.7 --fast --1	610 MB/s	1763 MB/s	86932028	41.02	12 files
brotli 1.2.0 -0	429 MB/s	386 MB/s	78306095	36.95	12 files
snappy 1.2.2	756 MB/s	1849 MB/s	101352257	47.82	12 files

Benchmark x86_64

Benchmarks were conducted using lzbench 2.2.1 (from @inikep), compiled with GCC 13.3.0 using MOREFLAGS="-march=native" on Linux 64-bits Ubuntu 24.04. The reference hardware is an AMD EPYC 7763 processor (x86_64). All performance metrics reflect single-threaded execution on the standard Silesia Corpus.

Compressor name	Compression	Decompress.	Compr. size	Ratio	Filename
memcpy	18697 MB/s	18663 MB/s	211938580	100.00	12 files
zxc 0.8.0 -1	642 MB/s	6779 MB/s	130408237	61.53	12 files
zxc 0.8.0 -2	414 MB/s	5778 MB/s	114657730	54.10	12 files
zxc 0.8.0 -3	171 MB/s	3849 MB/s	98234598	46.35	12 files
zxc 0.8.0 -4	122 MB/s	3674 MB/s	91698141	43.27	12 files
zxc 0.8.0 -5	67.0 MB/s	3495 MB/s	86054926	40.60	12 files
lz4 1.10.0	592 MB/s	3573 MB/s	100880147	47.60	12 files
lz4 1.10.0 --fast -17	1033 MB/s	4116 MB/s	131723524	62.15	12 files
lz4hc 1.10.0 -12	11.2 MB/s	3484 MB/s	77262399	36.46	12 files
zstd 1.5.7 -1	412 MB/s	1198 MB/s	73229468	34.55	12 files
zstd 1.5.7 --fast --1	451 MB/s	1573 MB/s	86932028	41.02	12 files
brotli 1.2.0 -0	354 MB/s	281 MB/s	78306095	36.95	12 files
snappy 1.2.2	611 MB/s	1592 MB/s	101464727	47.87	12 files

---

Installation

Option 1: Download Release (GitHub)

1. Go to the Releases page.

2. Download the archive matching your architecture:

   macOS:

   • zxc-macos-arm64.tar.gz (NEON optimizations included).

   Linux:

   • zxc-linux-aarch64.tar.gz (NEON optimizations included).
   • zxc-linux-x86_64.tar.gz (Runtime dispatch for AVX2/AVX512).

   Windows:

   • zxc-windows-x64.zip (Runtime dispatch for AVX2/AVX512).

3. Extract and install:

   tar -xzf zxc-linux-x86_64.tar.gz -C /usr/local

   Each archive contains:

   bin/zxc                          # CLI binary
   include/                         # C headers (zxc.h, zxc_buffer.h, ...)
   lib/libzxc.a                     # Static library
   lib/pkgconfig/zxc.pc             # pkg-config support
   lib/cmake/zxc/zxcConfig.cmake    # CMake find_package(zxc) support
   

4. Use in your project:

   CMake:

   find_package(zxc REQUIRED)
   target_link_libraries(myapp PRIVATE zxc::zxc_lib)

   pkg-config:

   cc myapp.c $(pkg-config --cflags --libs zxc) -o myapp

Option 2: vcpkg

Classic mode:

vcpkg install zxc

Manifest mode (add to vcpkg.json):

{
  "dependencies": ["zxc"]
}

Then in your CMake project:

find_package(zxc CONFIG REQUIRED)
target_link_libraries(myapp PRIVATE zxc::zxc_lib)

Option 3: Building from Source

Requirements: CMake (3.14+), C17 Compiler (Clang/GCC/MSVC).

git clone https://github.com/hellobertrand/zxc.git
cd zxc
cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --parallel

# Run tests
ctest --test-dir build -C Release --output-on-failure

# CLI usage
./build/zxc --help

# Install library, headers, and CMake/pkg-config files
sudo cmake --install build

CMake Options

Option	Default	Description
BUILD_SHARED_LIBS	OFF	Build shared libraries instead of static (libzxc.so, libzxc.dylib, zxc.dll)
ZXC_NATIVE_ARCH	ON	Enable -march=native for maximum performance
ZXC_ENABLE_LTO	ON	Enable Link-Time Optimization (LTO)
ZXC_PGO_MODE	OFF	Profile-Guided Optimization mode (OFF, GENERATE, USE)
ZXC_BUILD_CLI	ON	Build command-line interface
ZXC_BUILD_TESTS	ON	Build unit tests
ZXC_ENABLE_COVERAGE	OFF	Enable code coverage generation (disables LTO/PGO)

# Build shared library
cmake -B build -DBUILD_SHARED_LIBS=ON

# Portable build (without -march=native)
cmake -B build -DZXC_NATIVE_ARCH=OFF

# Library only (no CLI, no tests)
cmake -B build -DZXC_BUILD_CLI=OFF -DZXC_BUILD_TESTS=OFF

# Code coverage build
cmake -B build -DZXC_ENABLE_COVERAGE=ON

---

Compression Levels

• Level 1, 2 (Fast): Optimized for real-time assets (Gaming, UI).
• Level 3, 4 (Balanced): A strong middle-ground offering efficient compression speed and a ratio superior to LZ4.
• Level 5 (Compact): The best choice for Embedded, Firmware, or Archival. Better compression than LZ4 and significantly faster decoding than Zstd.

---

Usage

1. CLI

The CLI is perfect for benchmarking or manually compressing assets.

# Basic Compression (Level 3 is default)
zxc -z input_file output_file

# High Compression (Level 5)
zxc -z -5 input_file output_file

# -z for compression can be omitted
zxc input_file output_file

# as well as output file; it will be automatically assigned to input_file.xc
zxc input_file

# Decompression
zxc -d compressed_file output_file

# Benchmark Mode (Testing speed on your machine)
zxc -b input_file

2. API

ZXC provides a thread-safe, stateless API with two usage patterns:

Buffer API (In-Memory)

#include "zxc.h"

// Compression
uint64_t bound = zxc_compress_bound(src_size);
size_t compressed_size = zxc_compress(src, src_size, dst, bound, level, checksum);

// Decompression
size_t decompressed_size = zxc_decompress(src, src_size, dst, dst_capacity, checksum);

Stream API (Files, Multi-Threaded)

#include "zxc.h"

// Compression
int64_t result = zxc_stream_compress(f_in, f_out, threads, level, checksum);

// Decompression
int64_t result = zxc_stream_decompress(f_in, f_out, threads, checksum);

Features:

• Caller-allocated buffers with explicit bounds
• Thread-safe (stateless)
• Multi-threaded streaming (auto-detects CPU cores)
• Optional checksum validation

See complete examples and advanced usage →

Language Bindings

Official wrappers maintained in this repository:

Language	Package Manager	Install Command	Documentation	Author
Rust	crates.io	cargo add zxc-compress	README	@hellobertrand
Python	PyPI	pip install zxc-compress	README	@nuberchardzer1
Node.js	npm	npm install zxc-compress	README	@hellobertrand

Community-maintained bindings:

Language	Package Manager	Install Command	Repository	Author
Go	pkg.go.dev	go get github.com/meysam81/go-zxc	https://github.com/meysam81/go-zxc	@meysam81

Safety & Quality

• Unit Tests: Comprehensive test suite with CTest integration.
• Continuous Fuzzing: Integrated with ClusterFuzzLite suites.
• Static Analysis: Checked with Cppcheck & Clang Static Analyzer.
• CodeQL Analysis: GitHub Advanced Security scanning for vulnerabilities.
• Code Coverage: Automated tracking with Codecov integration.
• Dynamic Analysis: Validated with Valgrind and ASan/UBSan in CI pipelines.
• Safe API: Explicit buffer capacity is required for all operations.

License & Credits

ZXC Copyright © 2025-2026, Bertrand Lebonnois and contributors. Licensed under the BSD 3-Clause License. See LICENSE for details.

Third-Party Components:

• rapidhash by Nicolas De Carli (MIT) - Used for high-speed, platform-independent checksums.