Question

我正在尝试将UInt16转换为位数组，我从哪里开始？

我需要将UInt16转换为数组，以便可以移位位。例如，向右移动1110等于2等于1011，或者如果我这样做

var i: UInt16 = 5
i = i >> 3

它将返回0，但是我希望它返回40960。在二进制文件中，它将类似于

0000000000000101 >> 3 = 1010000000000000 (40960)

我不知道从哪里开始这个问题，所以我们将不胜感激

Answer 1

您可以这样旋转16位无符号整数的位：

func rotateLeft(_ n: UInt16, by shift: Int) -> UInt16 {
    let sh = shift % 16

    guard sh != 0 else { return n }

    return n << sh + n >> (sh.signum() * (16 - abs(sh)))
}

let num: UInt16 = 0b0100_0000_0000_0000     //16384
let result1 = rotateLeft(num, by: 2)        //1
let result2 = rotateLeft(num, by: -2)       //4096

let num2: UInt16 = 0b1000_0000_0000_0001    //32769
let result3 = rotateLeft(num2, by: 1)       //3
let result4 = rotateLeft(num2, by: -1)      //49152

Answer 2

您可以定义一个新的移位运算符，它定义“环绕”或二进制旋转，如下所示：

infix operator <<&
infix operator >>&

extension BinaryInteger {
    static func <<&<RHS:BinaryInteger>(lhs:Self, rhs:RHS) -> Self {
        // Do normal bit shifting
        let shifted = lhs << rhs
        // If the result is 0, do a rotation by shifting in the opposite direction
        // by the maximum number of bits - original rotation
        // otherwise return the regularly shifted value
        return shifted == 0 ? lhs >> (lhs.bitWidth - Int(rhs)) : shifted
    }

    static func >>&<RHS:BinaryInteger>(lhs:Self, rhs:RHS) -> Self {
        let shifted = lhs >> rhs
        return shifted == 0 ? lhs << (lhs.bitWidth - Int(rhs)) : shifted
    }
}

然后像普通的移位运算符一样使用它：

UInt16(5) >>& 3 // 40960
UInt8(128) <<& 1 // 1
UInt8(128) << 1 // 0

如何将UInt16转换为位数组

2 个答案: