rapidyenc-kotlin-wrapper

Kotlin JNA wrapper for rapidyenc, a high-performance yEnc encoder/decoder with SIMD acceleration.

Features

• yEnc encoding and decoding with SIMD-accelerated kernels (SSE2, AVX2, NEON, etc.)
• Incremental encoding/decoding for streaming use cases
• CRC32 computation, combination, and field operations
• Zero-copy ByteBuffer API for high-throughput paths
• Thread-safe after automatic one-time initialization
• No manual memory management required

Installation

Add JitPack and the dependency to your build.gradle.kts:

repositories {
    maven("https://jitpack.io")
    mavenCentral()
}

dependencies {
    implementation("com.github.skjaere:rapidyenc-kotlin-wrapper:TAG")
}

Replace TAG with a release tag, commit hash, or branch name (e.g. v0.1.0, main-SNAPSHOT).

Usage

All functions are accessed through the RapidYenc object. Initialization is automatic and thread-safe.

Encoding

import io.skjaere.yenc.RapidYenc

// Basic encode
val encoded = RapidYenc.encode(data)

// Incremental encode with column tracking
val result1 = RapidYenc.encodeEx(chunk1, lineSize = 128, column = 0, isEnd = false)
val result2 = RapidYenc.encodeEx(chunk2, column = result1.column, isEnd = true)

// Zero-copy with direct ByteBuffers
val maxLen = RapidYenc.encodeMaxLength(src.remaining().toLong()).toInt()
val dest = ByteBuffer.allocateDirect(maxLen)
RapidYenc.encode(src, dest)

Decoding

// Basic decode
val decoded = RapidYenc.decode(encoded)

// Decode with NNTP dot unstuffing and state tracking
val result = RapidYenc.decodeEx(encoded, isRaw = true, state = RapidYencDecoderState.CRLF)

// Incremental decode with end-sequence detection
val result = RapidYenc.decodeIncremental(data)
when (result.end) {
    RapidYencDecoderEnd.CONTROL -> println("Found =yend at byte ${result.bytesConsumed}")
    RapidYencDecoderEnd.ARTICLE -> println("Found article end")
    RapidYencDecoderEnd.NONE    -> println("No end sequence found")
}

CRC32

// Compute CRC32
val crc = RapidYenc.crc32(data)

// Incremental CRC32
val crc1 = RapidYenc.crc32(part1)
val crc2 = RapidYenc.crc32(part2, initCrc = crc1)

// Combine two independent CRC32 values
val combined = RapidYenc.crc32Combine(crc1, crc2, part2.size.toLong())

API Reference

Encoding

Function	Description
encode(ByteArray): ByteArray	Encode bytes using yEnc
encodeEx(ByteArray, lineSize, column, isEnd): EncodeResult	Incremental encode with column tracking
encode(ByteBuffer, ByteBuffer): Long	Zero-copy encode with direct buffers
encodeMaxLength(Long, Int): Long	Maximum output buffer size for a given input
encodeKernel(): RapidYencKernel	ISA kernel selected for encoding

Decoding

Function	Description
decode(ByteArray): ByteArray	Decode yEnc-encoded bytes
decodeEx(ByteArray, isRaw, state): DecodeExResult	Decode with NNTP dot unstuffing and state tracking
decodeIncremental(ByteArray, state): IncrementalDecodeResult	Decode with end-sequence detection
decode(ByteBuffer, ByteBuffer): Long	Zero-copy decode with direct buffers
decodeKernel(): RapidYencKernel	ISA kernel selected for decoding

CRC32

Function	Description
crc32(ByteArray, UInt): UInt	Compute CRC32 (supports incremental via initCrc)
crc32Combine(UInt, UInt, Long): UInt	Combine two CRC32 values
crc32Zeros(UInt, Long): UInt	CRC32 after appending zero bytes
crc32Unzero(UInt, Long): UInt	Inverse of crc32Zeros
crc32Multiply(UInt, UInt): UInt	Multiply in CRC32 field
crc32TwoPow(Long): UInt	2^n in CRC32 field
crc32TwoFiftySixPow(Long): UInt	2^(8n) in CRC32 field
crcKernel(): RapidYencKernel	ISA kernel selected for CRC32

Other

Function	Description
version(): Triple<Int, Int, Int>	Library version as (major, minor, patch)
versionRaw(): Int	Raw version in 0xMMmmpp format

Low-Level Access

For direct access to the C API, use RapidYencLibrary which exposes all 20 native functions via JNA direct mapping:

import io.skjaere.yenc.RapidYencLibrary

RapidYencLibrary.rapidyenc_encode_init()
val version = RapidYencLibrary.rapidyenc_version()

Build

Requires Java 25+ and uses the Gradle wrapper (Gradle 9.0):

./gradlew build              # Build and run tests
./gradlew publishToMavenLocal  # Install to ~/.m2

Platform Support

Ships with native libraries for Linux x86-64 and Linux aarch64. JNA loads the right librapidyenc.so for the host architecture automatically.

License

The rapidyenc C library is created by animetosho.