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DualCam Communication Protocol (view source)
Revision as of 11:53, 17 August 2022
, 11:53, 17 August 2022→CRC-16 calculation
==CRC-16 calculation==
==CRC-16 calculation==
CRC is calculated with using 3 input variables:
1. init_value - last packet CRC (or 0 if it's the first packet)<br>
2. poly - binary polynomial expression (0x8408 in our case)<br>
3. data - raw data of the packet (not including the first 4 bytes (cmd ID and packet size) and 2 last bytes (the CRC)
An example of structure can be found below:
function crc16_generic(init_value, poly, data) {
let RetVal = init_value;
let offset;
for (offset = 0; offset < data.length; offset++) {
let bit;
RetVal ^= data[offset];
for (bit = 0; bit < 8; bit++) {
let carry = RetVal & 0x01;
RetVal >>= 0x01;
if (carry) {
RetVal ^= poly;
}
}
}
return RetVal;
}
CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. The algorithm how to calculate CRC-16 (also known as CRC-16/IBM) you will find below.
CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. The algorithm how to calculate CRC-16 (also known as CRC-16/IBM) you will find below.
