// initialize crc8 to zero prior to first call
void ow_docrc8(int bit) {
if (bit) {
if (crc8 & 1)
crc8 ^= 0x19;
}
else {
if ((crc8 &1) == 0)
crc8 ^= 0x19;
}
if (crc8 & 1)
crc8 = (crc8 >> 1) | 0x80;
else
crc8 = (crc8 >> 1) & ~0x80;
}