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package com.github.jodersky.mavlink
/**
* X.25 CRC calculation for MAVlink messages. The checksum must be initialized,
* updated with each field of a message, and then finished with the message
* id.
*/
case class Crc(val crc: Int = 0xffff) extends AnyVal {
/**
* Accumulates data into a new checksum.
*/
def accumulate(datum: Byte): Crc = {
val d = datum & 0xff
var tmp = d ^ (crc & 0xff)
tmp ^= (tmp << 4) & 0xff;
Crc(
((crc >> 8) & 0xff) ^ (tmp << 8) ^ (tmp << 3) ^ ((tmp >> 4) & 0xff))
}
def accumulate(data: Seq[Byte]): Crc = {
var next = this
for (d <- data) {
next = next.accumulate(d)
}
next
}
/** Least significant byte of checksum. */
def lsb: Byte = crc.toByte
/** Most significant byte of checksum. */
def msb: Byte = (crc >> 8).toByte
}
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