leb128

Go implementation of signed/unsigned LEB128. Encodes/decodes 8 byte integers.

Usage

Full documentation is available at pkg.go.dev.

Decoding

Read from an io.Reader in to an int64 or uint64:

package main

import (
	"bytes"
	"fmt"

	"github.com/jcalabro/leb128"
)

func unsigned() {
	// Encodings whose value would not fit in 64 bits return leb128.ErrOverflow.
	// An empty reader returns io.EOF; a truncated encoding (continuation bit
	// set on the final byte read) returns io.ErrUnexpectedEOF.

	buf := bytes.NewBuffer([]byte{128, 2})
	num, err := leb128.DecodeU64(buf)
	if err != nil {
		panic(err)
	}
	fmt.Println(num) // 256
}

func signed() {
	buf := bytes.NewBuffer([]byte{128, 126})
	num, err := leb128.DecodeS64(buf)
	if err != nil {
		panic(err)
	}
	fmt.Println(num) // -256
}

func main() {
	unsigned()
	signed()
}

Encoding

Convert an int64 or uint64 to a []byte:

package main

import (
	"fmt"

	"github.com/jcalabro/leb128"
)

func unsigned() {
	buf := leb128.EncodeU64(256)
	fmt.Println(buf) // [128 2]
}

func signed() {
	buf := leb128.EncodeS64(-256)
	fmt.Println(buf) // [128 126]
}

func main() {
	unsigned()
	signed()
}