public static ReadableCharBuf ascii(char[] values, int start, int length) {
byte[] data = new byte[length];
for (int i = start; i < (start + length); i++) {
char c = values[i];
if (c >= '\u0080') {
throw new RuntimeException(new UnmappableCharacterException(2));
}
data[i] = (byte) c;
}
return new ByteArrayReadOnlyAsciiBuf(data);
}