github.com/bamzi/go-ethereum@v1.6.7-0.20170704111104-138f26c93af1/common/bytes.go (about) 1 // Copyright 2014 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 // Package common contains various helper functions. 18 package common 19 20 import ( 21 "encoding/hex" 22 ) 23 24 func ToHex(b []byte) string { 25 hex := Bytes2Hex(b) 26 // Prefer output of "0x0" instead of "0x" 27 if len(hex) == 0 { 28 hex = "0" 29 } 30 return "0x" + hex 31 } 32 33 func FromHex(s string) []byte { 34 if len(s) > 1 { 35 if s[0:2] == "0x" || s[0:2] == "0X" { 36 s = s[2:] 37 } 38 if len(s)%2 == 1 { 39 s = "0" + s 40 } 41 return Hex2Bytes(s) 42 } 43 return nil 44 } 45 46 // Copy bytes 47 // 48 // Returns an exact copy of the provided bytes 49 func CopyBytes(b []byte) (copiedBytes []byte) { 50 copiedBytes = make([]byte, len(b)) 51 copy(copiedBytes, b) 52 53 return 54 } 55 56 func HasHexPrefix(str string) bool { 57 l := len(str) 58 return l >= 2 && str[0:2] == "0x" 59 } 60 61 func IsHex(str string) bool { 62 l := len(str) 63 return l >= 4 && l%2 == 0 && str[0:2] == "0x" 64 } 65 66 func Bytes2Hex(d []byte) string { 67 return hex.EncodeToString(d) 68 } 69 70 func Hex2Bytes(str string) []byte { 71 h, _ := hex.DecodeString(str) 72 73 return h 74 } 75 76 func Hex2BytesFixed(str string, flen int) []byte { 77 h, _ := hex.DecodeString(str) 78 if len(h) == flen { 79 return h 80 } else { 81 if len(h) > flen { 82 return h[len(h)-flen:] 83 } else { 84 hh := make([]byte, flen) 85 copy(hh[flen-len(h):flen], h[:]) 86 return hh 87 } 88 } 89 } 90 91 func RightPadBytes(slice []byte, l int) []byte { 92 if l <= len(slice) { 93 return slice 94 } 95 96 padded := make([]byte, l) 97 copy(padded, slice) 98 99 return padded 100 } 101 102 func LeftPadBytes(slice []byte, l int) []byte { 103 if l <= len(slice) { 104 return slice 105 } 106 107 padded := make([]byte, l) 108 copy(padded[l-len(slice):], slice) 109 110 return padded 111 }