crc32b in Kotlin

crc32b.kt

private const val CRC32_POLYNOMIAL_MSB = 0xEDB88320.toInt()
private val CRC32_REVERSE_TABLE = IntArray(256) {
    var crc = it
    repeat(8) {
        if ((crc and 1) != 0) {
            crc = (crc ushr  1) xor CRC32_POLYNOMIAL_MSB
        } else {
            crc = crc ushr 1
        }
    }
    crc
}

fun crc32b(data: ByteArray, offset: Int = 0, length: Int = data.size): Int {
    var crc = -1
    var i = offset
    val limit = offset + length
    while (i < limit) {
        crc = CRC32_REVERSE_TABLE[(crc xor data[i++].toInt()) and 0xFF] xor (crc ushr 8)
    }
    return crc.inv()
}