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.
46 lines
981 B
46 lines
981 B
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)
|
|
}
|
|
|
|
// Hex2Bytes returns the bytes represented by the hexadecimal string str.
|
|
func Hex2Bytes(str string) []byte {
|
|
h, _ := hex.DecodeString(str)
|
|
return h
|
|
}
|
|
|
|
// 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) int64 {
|
|
if arr == nil {
|
|
return 0
|
|
}
|
|
if len(arr) == 0 {
|
|
return 0
|
|
}
|
|
count := 0
|
|
for i := range arr {
|
|
count += countOneBitsInByte(arr[i])
|
|
}
|
|
return int64(count)
|
|
}
|
|
|