github.com/ylsGit/go-ethereum@v1.6.5/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  }