nibble
int nibble;
for (nibble = 0; nibble < 2; ++nibble) {
uint8_t nibble;
nibble = buf[index / 2];
nibble >>= 4;
nibble &= 0x0F;
return nibble;
if ((hi = nibble(mac[i])) == -1 ||
(lo = nibble(mac[i+2])) == -1)
if ((hi = nibble(mac[i])) == -1 ||
(lo = nibble(mac[i+1])) == -1)