path: root/common/bytes.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package common contains various helper functions.
package common

import (
    "encoding/hex"
)

func ToHex(b []byte) string {
    hex := Bytes2Hex(b)
    // Prefer output of "0x0" instead of "0x"
    if len(hex) == 0 {
        hex = "0"
    }
    return "0x" + hex
}

func FromHex(s string) []byte {
    if len(s) > 1 {
        if s[0:2] == "0x" || s[0:2] == "0X" {
            s = s[2:]
        }
    }
    if len(s)%2 == 1 {
        s = "0" + s
    }
    return Hex2Bytes(s)
}

// Copy bytes
//
// Returns an exact copy of the provided bytes
func CopyBytes(b []byte) (copiedBytes []byte) {
    if b == nil {
        return nil
    }
    copiedBytes = make([]byte, len(b))
    copy(copiedBytes, b)

    return
}

func HasHexPrefix(str string) bool {
    l := len(str)
    return l >= 2 && str[0:2] == "0x"
}

func IsHex(str string) bool {
    l := len(str)
    return l >= 4 && l%2 == 0 && str[0:2] == "0x"
}

func Bytes2Hex(d []byte) string {
    return hex.EncodeToString(d)
}

func Hex2Bytes(str string) []byte {
    h, _ := hex.DecodeString(str)

    return h
}

func Hex2BytesFixed(str string, flen int) []byte {
    h, _ := hex.DecodeString(str)
    if len(h) == flen {
        return h
    } else {
        if len(h) > flen {
            return h[len(h)-flen:]
        } else {
            hh := make([]byte, flen)
            copy(hh[flen-len(h):flen], h[:])
            return hh
        }
    }
}

func RightPadBytes(slice []byte, l int) []byte {
    if l <= len(slice) {
        return slice
    }

    padded := make([]byte, l)
    copy(padded, slice)

    return padded
}

func LeftPadBytes(slice []byte, l int) []byte {
    if l <= len(slice) {
        return slice
    }

    padded := make([]byte, l)
    copy(padded[l-len(slice):], slice)

    return padded
}