You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
104 lines
2.2 KiB
104 lines
2.2 KiB
package utils
|
|
|
|
import "encoding/hex"
|
|
|
|
// use to look up number of 1 bit in 4 bits
|
|
var halfByteLookup = [16]int{0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4}
|
|
|
|
// FromHex returns the bytes represented by the hexadecimal string s.
|
|
// s may be prefixed with "0x".
|
|
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)
|
|
}
|
|
|
|
// CopyBytes 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
|
|
}
|
|
|
|
// HasHexPrefix validates str begins with '0x' or '0X'.
|
|
func HasHexPrefix(str string) bool {
|
|
return len(str) >= 2 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X')
|
|
}
|
|
|
|
// isHexCharacter returns bool of c being a valid hexadecimal.
|
|
func isHexCharacter(c byte) bool {
|
|
return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F')
|
|
}
|
|
|
|
// IsHex validates whether each byte is valid hexadecimal string.
|
|
func IsHex(str string) bool {
|
|
if len(str)%2 != 0 {
|
|
return false
|
|
}
|
|
for _, c := range []byte(str) {
|
|
if !isHexCharacter(c) {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Hex2Bytes returns the bytes represented by the hexadecimal string str.
|
|
func Hex2Bytes(str string) []byte {
|
|
h, _ := hex.DecodeString(str)
|
|
return h
|
|
}
|
|
|
|
// RightPadBytes zero-pads slice to the right up to length l.
|
|
func RightPadBytes(slice []byte, l int) []byte {
|
|
if l <= len(slice) {
|
|
return slice
|
|
}
|
|
|
|
padded := make([]byte, l)
|
|
copy(padded, slice)
|
|
|
|
return padded
|
|
}
|
|
|
|
// LeftPadBytes zero-pads slice to the left up to length l.
|
|
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
|
|
}
|
|
|
|
// counts number of one bits in a byte
|
|
func countOneBitsInByte(by byte) int {
|
|
return halfByteLookup[by&0x0F] + halfByteLookup[by>>4]
|
|
}
|
|
|
|
// CountOneBits counts the number of 1 bit in byte array
|
|
func CountOneBits(arr []byte) int {
|
|
if arr == nil {
|
|
return 0
|
|
}
|
|
if len(arr) == 0 {
|
|
return 0
|
|
}
|
|
count := 0
|
|
for i := range arr {
|
|
count += countOneBitsInByte(arr[i])
|
|
}
|
|
return count
|
|
}
|
|
|