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98 lines
2.1 KiB
98 lines
2.1 KiB
package utils
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import "encoding/hex"
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// use to look up number of 1 bit in 4 bits
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var halfByteLookup = [16]int{0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4}
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// FromHex returns the bytes represented by the hexadecimal string s.
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// s may be prefixed with "0x".
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func FromHex(s string) []byte {
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if len(s) > 1 {
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if s[0:2] == "0x" || s[0:2] == "0X" {
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s = s[2:]
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}
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}
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if len(s)%2 == 1 {
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s = "0" + s
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}
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return Hex2Bytes(s)
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}
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// CopyBytes returns an exact copy of the provided bytes.
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func CopyBytes(b []byte) (copiedBytes []byte) {
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if b == nil {
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return nil
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}
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copiedBytes = make([]byte, len(b))
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copy(copiedBytes, b)
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return
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}
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// HasHexPrefix validates str begins with '0x' or '0X'.
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func HasHexPrefix(str string) bool {
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return len(str) >= 2 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X')
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}
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// isHexCharacter returns bool of c being a valid hexadecimal.
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func isHexCharacter(c byte) bool {
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return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F')
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}
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// IsHex validates whether each byte is valid hexadecimal string.
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func IsHex(str string) bool {
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if len(str)%2 != 0 {
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return false
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}
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for _, c := range []byte(str) {
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if !isHexCharacter(c) {
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return false
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}
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}
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return true
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}
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// Hex2Bytes returns the bytes represented by the hexadecimal string str.
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func Hex2Bytes(str string) []byte {
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h, _ := hex.DecodeString(str)
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return h
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}
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// RightPadBytes zero-pads slice to the right up to length l.
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func RightPadBytes(slice []byte, l int) []byte {
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if l <= len(slice) {
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return slice
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}
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padded := make([]byte, l)
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copy(padded, slice)
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return padded
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}
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// LeftPadBytes zero-pads slice to the left up to length l.
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func LeftPadBytes(slice []byte, l int) []byte {
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if l <= len(slice) {
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return slice
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}
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padded := make([]byte, l)
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copy(padded[l-len(slice):], slice)
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return padded
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}
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// counts number of one bits in a byte
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func countOneBitsInByte(by byte) int {
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return halfByteLookup[by&0x0F] + halfByteLookup[by>>4]
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}
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// CountOneBits counts the number of 1 bit in byte array
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func CountOneBits(arr []byte) int {
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count := 0
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for i := range arr {
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count += countOneBitsInByte(arr[i])
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}
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return count
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}
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