- ord: documentation ( source)
- sprintf: documentation ( source)
<?php
echo sprintf("%x",getCrc16("\x08\x02\x00\x00\x01\x43\xEF\x3A", 0, 0xA001, 0));
function getCrc16($buffer, $offset, $polynom, $preset) {
$preset &= 0xFFFF;
$polynom &= 0xFFFF;
$bufLen = strlen($buffer);
$crc = $preset;
for($i = 0; $i < $bufLen; $i++) {
$data = ord($buffer[($i + $offset)%$bufLen]);
$crc ^= $data;
for ($j = 0; $j < 8; $j++) {
if (($crc & 0x0001) != 0) {
$crc = ($crc >> 1) ^ $polynom;
} else {
$crc = $crc >> 1;
}
}
}
return $crc & 0xFFFF;
}