bit_shifting.kt

fun toInt(b1: Byte, b2: Byte, b3: Byte, b4: Byte): Int {
    return b1.toInt().and(0xff).shl(8 * 3)
    	.or(b2.toInt().and(0xff).shl(8 * 2))
    	.or(b3.toInt().and(0xff).shl(8 * 1))
    	.or(b4.toInt().and(0xff))
}

// 0        1        2        3
// 01234567 01234567 01234567 01234567
// 01111111 10100001 10110010 11000011
// 7f       a1       b2       c3
// 127      161      178      195

fun bitsShifting() {
    val int32: Int = 2141303491
    println("int32: $int32")
    val b1: Byte = int32.shr(8 * 3).toByte()
    val b2: Byte = int32.shr(8 * 2).toByte()
    val b3: Byte = int32.shr(8 * 1).toByte()
    val b4: Byte = int32.toByte()
    println("b1: ${b1.toInt() and 0xff}($b1)") // 127(127)
    println("b2: ${b2.toInt() and 0xff}($b2)") // 161(-95)
    println("b3: ${b3.toInt() and 0xff}($b3)") // 178(-78)
    println("b4: ${b4.toInt() and 0xff}($b4)") // 195(-61)
    val decoded = toInt(b1, b2, b3, b4)
    println("decoded: $decoded")
    check(int32 == decoded)
}