[]byte型をuint・int・stringに相互変換するヘルパー関数

はじめに

• いつもの通り、備忘録的めもです
• ビット・バイトのエンディアンに注意
• 気になるとことかあればコメントにて

コード

package helpers

import (
    "encoding/binary"
    "fmt"
    "strconv"
    "strings"
)

// Str2bytes converts string("00 00 00 00 00 00 00 00") to []byte
func Str2bytes(str string) []byte {
    bytes := make([]byte, 8)
    for i, e := range strings.Fields(str) {
        b, _ := strconv.ParseUint(e, 16, 64)
        bytes[i] = byte(b)
    }
    return bytes
}

// Bytes2str converts []byte to string("00 00 00 00 00 00 00 00")
func Bytes2str(bytes ...byte) string {
    strs := []string{}
    for _, b := range bytes {
        strs = append(strs, fmt.Sprintf("%02x", b))
    }
    return strings.Join(strs, " ")
}

// Bytes2uint converts []byte to uint64
func Bytes2uint(bytes ...byte) uint64 {
    padding := make([]byte, 8-len(bytes))
    i := binary.BigEndian.Uint64(append(padding, bytes...))
    return i
}

// Uint2bytes converts uint64 to []byte
func Uint2bytes(i uint64, size int) []byte {
    bytes := make([]byte, 8)
    binary.BigEndian.PutUint64(bytes, i)
    return bytes[8-size : 8]
}

// Bytes2int converts []byte to int64
func Bytes2int(bytes ...byte) int64 {
    if 0x7f < bytes[0] {
        mask := uint64(1<<uint(len(bytes)*8-1) - 1)

        bytes[0] &= 0x7f
        i := Bytes2uint(bytes...)
        i = (^i + 1) & mask
        return int64(-i)

    } else {
        i := Bytes2uint(bytes...)
        return int64(i)
    }
}

// Int2bytes converts int to []byte
func Int2bytes(i int, size int) []byte {
    var ui uint64
    if 0 < i {
        ui = uint64(i)
    } else {
        ui = (^uint64(-i) + 1)
    }
    return Uint2bytes(ui, size)
}