package reverse

import "unicode/utf8"

func swap(a *byte, b *byte) {
	*a ^= *b
	*b ^= *a
	*a ^= *b
}

func reverse(b []byte) {
	for i := 0; i < len(b); {
		_, sz := utf8.DecodeRune(b[i:])
		l := i
		r := i + sz - 1
		for l < r {
			swap(&b[l], &b[r])
			l++
			r--
		}
		i += sz
	}

	l := 0
	r := len(b) - 1
	for l < r {
		swap(&b[l], &b[r])
		l++
		r--
	}
}