import kotlin.random.Random
import kotlin.text.StringBuilder

fun main(args: Array<String>) {
    for (i in 0 until 1000) {
        val bitStringBuilder = StringBuilder()
        for (j in 0 until 8) {
            bitStringBuilder.append(if (Random.nextBoolean()) '1' else '0')
        }

        val method1Result = bin2dec1(bitStringBuilder.toString())
        val method2Result = bin2dec2(bitStringBuilder.toString())

        println("method 1: $method1Result; method 2: $method2Result")

        assert(method1Result == method2Result)
    }
}

fun bin2dec1(bitString: String): Byte {
    var b: Byte = 0
    for (i in 0 until 8) {
        b = (b.toInt() shl 1).toByte() // Shift old bits
        if (bitString[i] == '1') {
            b = (b.toInt() or 1).toByte() // Set new bit
        } else {
            b = (b.toInt() or 0).toByte() // Don't set new bit
        }
    }
    return b
}

fun bin2dec2(bitString: String): Byte {
    return if (bitString[0] == '1') {
        (-(bitString.replace('0', ' ').replace('1', '0').replace(' ', '1').toByte(2) + 1)).toByte()
    } else {
        bitString.toByte(2)
    }
}